diff --git a/src/main/aciodrv/device.c b/src/main/aciodrv/device.c
index 1765a18..8d47616 100644
--- a/src/main/aciodrv/device.c
+++ b/src/main/aciodrv/device.c
@@ -12,11 +12,14 @@
 /* Enable to dump all data to the logger */
 //#define AC_IO_MSG_LOG
 
-static uint8_t aciodrv_device_msg_counter = 1;
-static uint8_t aciodrv_device_node_count;
-static char aviodrv_device_node_products[16][4];
+struct aciodrv_device_ctx {
+    HANDLE fd;
+    char node_products[16][4]; // 16 devices max
+    uint8_t msg_counter;
+    uint8_t node_count;
+};
 
-static bool aciodrv_device_init(void)
+static bool aciodrv_device_init(struct aciodrv_device_ctx* device)
 {
     uint8_t init_seq[1] = {AC_IO_SOF};
     uint8_t read_buff[1] = {0x00};
@@ -24,18 +27,18 @@ static bool aciodrv_device_init(void)
     /* init/reset the device by sending 0xAA until 0xAA is returned */
     int read = 0;
     do {
-        if (aciodrv_port_write(init_seq, sizeof(init_seq)) <= 0) {
+        if (aciodrv_port_write(device->fd, init_seq, sizeof(init_seq)) <= 0) {
             return false;
         }
 
-        read = aciodrv_port_read(read_buff, sizeof(read_buff));
+        read = aciodrv_port_read(device->fd, read_buff, sizeof(read_buff));
     } while ((read <= 0) || (read_buff[0] != init_seq[0]));
 
     if (read > 0) {
         log_warning("Obtained SOF, clearing out buffer now");
         /* empty buffer by reading all data */
         while (read > 0) {
-            read = aciodrv_port_read(init_seq, sizeof(init_seq));
+            read = aciodrv_port_read(device->fd, init_seq, sizeof(init_seq));
         }
         log_warning("Cleared buffer, init done");
 
@@ -57,7 +60,7 @@ aciodrv_device_log_buffer(const char *msg, const uint8_t *buffer, int length)
 }
 #endif
 
-static bool aciodrv_device_send(const uint8_t *buffer, int length)
+static bool aciodrv_device_send(struct aciodrv_device_ctx* device, const uint8_t *buffer, int length)
 {
     uint8_t send_buf[512];
     int send_buf_pos = 0;
@@ -98,7 +101,7 @@ static bool aciodrv_device_send(const uint8_t *buffer, int length)
     aciodrv_device_log_buffer("Send (2)", send_buf, send_buf_pos);
 #endif
 
-    if (aciodrv_port_write(send_buf, send_buf_pos) != send_buf_pos) {
+    if (aciodrv_port_write(device->fd, send_buf, send_buf_pos) != send_buf_pos) {
         log_warning("Sending data with length %d failed", send_buf_pos);
         return false;
     }
@@ -106,7 +109,7 @@ static bool aciodrv_device_send(const uint8_t *buffer, int length)
     return true;
 }
 
-static int aciodrv_device_receive(uint8_t *buffer, int size)
+static int aciodrv_device_receive(struct aciodrv_device_ctx* device, uint8_t *buffer, int size)
 {
     uint8_t recv_buf[512];
     int recv_size = 0;
@@ -118,7 +121,7 @@ static int aciodrv_device_receive(uint8_t *buffer, int size)
        of 0xAAs before we get a valid message. */
     recv_buf[0] = AC_IO_SOF;
     do {
-        read = aciodrv_port_read(recv_buf, 1);
+        read = aciodrv_port_read(device->fd, recv_buf, 1);
     } while (recv_buf[0] == AC_IO_SOF);
 
     if (read > 0) {
@@ -137,7 +140,7 @@ static int aciodrv_device_receive(uint8_t *buffer, int size)
            non-zero read. */
         while (size > 0) {
             do {
-                read = aciodrv_port_read(recv_buf + recv_size, 1);
+                read = aciodrv_port_read(device->fd, recv_buf + recv_size, 1);
             } while (read == 0);
 
             if (read < 0) {
@@ -150,7 +153,8 @@ static int aciodrv_device_receive(uint8_t *buffer, int size)
                 /* next byte is our real data
                    overwrite escape byte */
                 do {
-                    read = aciodrv_port_read(recv_buf + recv_size, 1);
+                    read = aciodrv_port_read(
+                        device->fd, recv_buf + recv_size, 1);
                 } while (read == 0);
 
                 if (read < 0) {
@@ -195,7 +199,7 @@ static int aciodrv_device_receive(uint8_t *buffer, int size)
     return -1;
 }
 
-static uint8_t aciodrv_device_enum_nodes(void)
+static uint8_t aciodrv_device_enum_nodes(struct aciodrv_device_ctx* device)
 {
     struct ac_io_message msg;
 
@@ -205,7 +209,9 @@ static uint8_t aciodrv_device_enum_nodes(void)
     msg.cmd.count = 0;
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + 1)) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + 1)) {
         log_warning("Enumerating nodes failed");
         return 0;
     }
@@ -215,7 +221,7 @@ static uint8_t aciodrv_device_enum_nodes(void)
     return msg.cmd.count;
 }
 
-static bool aciodrv_device_get_version(uint8_t node_id, char product[4])
+static bool aciodrv_device_get_version(struct aciodrv_device_ctx* device, uint8_t node_id, char product[4])
 {
     struct ac_io_message msg;
 
@@ -224,6 +230,7 @@ static bool aciodrv_device_get_version(uint8_t node_id, char product[4])
     msg.cmd.nbytes = 0;
 
     if (!aciodrv_send_and_recv(
+            device,
             &msg,
             offsetof(struct ac_io_message, cmd.raw) +
                 sizeof(struct ac_io_version))) {
@@ -252,7 +259,7 @@ static bool aciodrv_device_get_version(uint8_t node_id, char product[4])
     return true;
 }
 
-static bool aciodrv_device_start_node(uint8_t node_id)
+static bool aciodrv_device_start_node(struct aciodrv_device_ctx* device, uint8_t node_id)
 {
     struct ac_io_message msg;
 
@@ -261,7 +268,9 @@ static bool aciodrv_device_start_node(uint8_t node_id)
     msg.cmd.nbytes = 0;
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + 1)) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + 1)) {
         log_warning("Starting node %d failed", node_id);
         return false;
     }
@@ -270,55 +279,64 @@ static bool aciodrv_device_start_node(uint8_t node_id)
     return true;
 }
 
-bool aciodrv_device_open(const char *port, int baud)
+struct aciodrv_device_ctx* aciodrv_device_open(const char *port_path, int baud)
 {
-    if (!aciodrv_port_open(port, baud)) {
+    HANDLE port = aciodrv_port_open(port_path, baud);
+    if (!port) {
+        return NULL;
+    }
+
+    struct aciodrv_device_ctx* device = malloc(sizeof(struct aciodrv_device_ctx));
+
+    device->fd = port;
+
+    if (!aciodrv_device_init(device)) {
+        aciodrv_device_close(device);
+        return NULL;
+    }
+
+    device->node_count = aciodrv_device_enum_nodes(device);
+    if (device->node_count == 0) {
+        aciodrv_device_close(device);
         return false;
     }
 
-    if (!aciodrv_device_init()) {
-        return false;
-    }
-
-    aciodrv_device_node_count = aciodrv_device_enum_nodes();
-    if (aciodrv_device_node_count == 0) {
-        return false;
-    }
-
-    for (uint8_t i = 0; i < aciodrv_device_node_count; i++) {
+    for (uint8_t i = 0; i < device->node_count; i++) {
         if (!aciodrv_device_get_version(
-                i + 1, aviodrv_device_node_products[i])) {
-            return false;
+                device, i + 1, device->node_products[i])) {
+            aciodrv_device_close(device);
+            return NULL;
         }
     }
 
-    for (uint8_t i = 0; i < aciodrv_device_node_count; i++) {
-        if (!aciodrv_device_start_node(i + 1)) {
-            return false;
+    for (uint8_t i = 0; i < device->node_count; i++) {
+        if (!aciodrv_device_start_node(device, i + 1)) {
+            aciodrv_device_close(device);
+            return NULL;
         }
     }
 
-    return true;
+    return device;
 }
 
-uint8_t aciodrv_device_get_node_count(void)
+uint8_t aciodrv_device_get_node_count(struct aciodrv_device_ctx* device)
 {
-    return aciodrv_device_node_count;
+    return device->node_count;
 }
 
-bool aciodrv_device_get_node_product_ident(uint8_t node_id, char product[4])
+bool aciodrv_device_get_node_product_ident(struct aciodrv_device_ctx* device, uint8_t node_id, char product[4])
 {
-    if (aciodrv_device_node_count == 0 || node_id > aciodrv_device_node_count) {
+    if (device->node_count == 0 || node_id > device->node_count) {
         return false;
     }
 
-    memcpy(product, aviodrv_device_node_products[node_id], 4);
+    memcpy(product, device->node_products[node_id], 4);
     return true;
 }
 
-bool aciodrv_send_and_recv(struct ac_io_message *msg, int resp_size)
+bool aciodrv_send_and_recv(struct aciodrv_device_ctx* device, struct ac_io_message *msg, int resp_size)
 {
-    msg->cmd.seq_no = aciodrv_device_msg_counter++;
+    msg->cmd.seq_no = device->msg_counter++;
     int send_size = offsetof(struct ac_io_message, cmd.raw) + msg->cmd.nbytes;
 
 #ifdef AC_IO_MSG_LOG
@@ -328,7 +346,7 @@ bool aciodrv_send_and_recv(struct ac_io_message *msg, int resp_size)
         msg->cmd.code,
         send_size);
 #endif
-    if (aciodrv_device_send((uint8_t *) msg, send_size) <= 0) {
+    if (aciodrv_device_send(device, (uint8_t *) msg, send_size) <= 0) {
         return false;
     }
 
@@ -337,7 +355,7 @@ bool aciodrv_send_and_recv(struct ac_io_message *msg, int resp_size)
 #ifdef AC_IO_MSG_LOG
     log_info("Beginning recv: (%d b)", resp_size);
 #endif
-    if (aciodrv_device_receive((uint8_t *) msg, resp_size) <= 0) {
+    if (aciodrv_device_receive(device, (uint8_t *) msg, resp_size) <= 0) {
         return false;
     }
 
@@ -352,7 +370,9 @@ bool aciodrv_send_and_recv(struct ac_io_message *msg, int resp_size)
     return true;
 }
 
-void aciodrv_device_close(void)
+void aciodrv_device_close(struct aciodrv_device_ctx* device)
 {
-    aciodrv_port_close();
+    aciodrv_port_close(device->fd);
+
+    free(device);
 }
diff --git a/src/main/aciodrv/device.h b/src/main/aciodrv/device.h
index 62f544b..b976d50 100644
--- a/src/main/aciodrv/device.h
+++ b/src/main/aciodrv/device.h
@@ -5,48 +5,56 @@
 
 #include "acio/acio.h"
 
+#include "windows.h"
+
+struct aciodrv_device_ctx;
+
 /**
  * Open an ACIO device connected to a serial port.
  *
  * @param port Port the device is connected to (e.g. "COM1")
  * @param baud Baud rate for communication (e.g. 57600 for ICCA)
- * @return True if opening the port and resetting the device was successful,
- *         false on error.
+ * @return opened device context, NULL on error
  */
-bool aciodrv_device_open(const char *port, int baud);
+struct aciodrv_device_ctx* aciodrv_device_open(const char *port_path, int baud);
 
 /**
  * Get the node count on the opened device.
  *
+ * @param device Context of opened device
  * @return Total num of nodes enumerated on the ACIO device.
  */
-uint8_t aciodrv_device_get_node_count(void);
+uint8_t aciodrv_device_get_node_count(struct aciodrv_device_ctx* device);
 
 /**
  * Get the product identifier of an enumerated node.
  *
+ * @param device Context of opened device
  * @param node_id Id of the node. Needs to be in range of the total node count.
  * @param product Buffer to return the product id to.
  * @return True on success, false on error. If True the variable product
  * contains the identifier of the queried node.
  */
-bool aciodrv_device_get_node_product_ident(uint8_t node_id, char product[4]);
+bool aciodrv_device_get_node_product_ident(struct aciodrv_device_ctx* device, uint8_t node_id, char product[4]);
 
 /**
  * Send a message to the ACIO bus and receive an answer.
  * Use this to implement the protocol for each type of device that can be
  * part of the bus.
  *
+ * @param device Context of opened device
  * @param msg Msg to send to the bus. Make sure that the buffer backing
  *        this message is big enough to receive the response as well.
  * @param resp_size Size of the expecting response.
  * @return True on success, false on error.
  */
-bool aciodrv_send_and_recv(struct ac_io_message *msg, int resp_size);
+bool aciodrv_send_and_recv(struct aciodrv_device_ctx* device, struct ac_io_message *msg, int resp_size);
 
 /**
  * Close the previously opened ACIO device.
+ * 
+ * @param device Context of opened device
  */
-void aciodrv_device_close(void);
+void aciodrv_device_close(struct aciodrv_device_ctx* device);
 
 #endif
\ No newline at end of file
diff --git a/src/main/aciodrv/icca.c b/src/main/aciodrv/icca.c
index 52a63a0..a3902a0 100644
--- a/src/main/aciodrv/icca.c
+++ b/src/main/aciodrv/icca.c
@@ -6,7 +6,9 @@
 
 #include "util/log.h"
 
-static bool aciodrv_icca_queue_loop_start(uint8_t node_id)
+static bool aciodrv_icca_queue_loop_start(
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id)
 {
     struct ac_io_message msg;
 
@@ -16,7 +18,9 @@ static bool aciodrv_icca_queue_loop_start(uint8_t node_id)
     msg.cmd.status = 0;
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + 1)) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + 1)) {
         log_warning("Starting queue loop failed");
         return false;
     }
@@ -27,9 +31,9 @@ static bool aciodrv_icca_queue_loop_start(uint8_t node_id)
     return true;
 }
 
-bool aciodrv_icca_init(uint8_t node_id)
+bool aciodrv_icca_init(struct aciodrv_device_ctx *device, uint8_t node_id)
 {
-    if (!aciodrv_icca_queue_loop_start(node_id + 1)) {
+    if (!aciodrv_icca_queue_loop_start(device, node_id + 1)) {
         return false;
     }
 
@@ -37,7 +41,10 @@ bool aciodrv_icca_init(uint8_t node_id)
 }
 
 bool aciodrv_icca_set_state(
-    uint8_t node_id, int slot_state, struct ac_io_icca_state *state)
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id,
+    int slot_state,
+    struct ac_io_icca_state *state)
 {
     struct ac_io_message msg;
 
@@ -49,7 +56,9 @@ bool aciodrv_icca_set_state(
     msg.cmd.raw[1] = slot_state;
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + msg.cmd.raw[0])) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + msg.cmd.raw[0])) {
         log_warning("Setting state of node %d failed", node_id + 1);
         return false;
     }
@@ -61,7 +70,10 @@ bool aciodrv_icca_set_state(
     return true;
 }
 
-bool aciodrv_icca_get_state(uint8_t node_id, struct ac_io_icca_state *state)
+bool aciodrv_icca_get_state(
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id,
+    struct ac_io_icca_state *state)
 {
     struct ac_io_message msg;
 
@@ -72,7 +84,9 @@ bool aciodrv_icca_get_state(uint8_t node_id, struct ac_io_icca_state *state)
     msg.cmd.count = sizeof(struct ac_io_icca_state);
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + msg.cmd.count)) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + msg.cmd.count)) {
         log_warning("Getting state of node %d failed", node_id + 1);
         return false;
     }
@@ -84,7 +98,10 @@ bool aciodrv_icca_get_state(uint8_t node_id, struct ac_io_icca_state *state)
     return true;
 }
 
-bool aciodrv_icca_read_card(uint8_t node_id, struct ac_io_icca_state *state)
+bool aciodrv_icca_read_card(
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id,
+    struct ac_io_icca_state *state)
 {
     struct ac_io_message msg;
 
@@ -95,7 +112,9 @@ bool aciodrv_icca_read_card(uint8_t node_id, struct ac_io_icca_state *state)
     msg.cmd.count = sizeof(struct ac_io_icca_state);
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + msg.cmd.count)) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + msg.cmd.count)) {
         log_warning("Reading card of node %d failed", node_id + 1);
         return false;
     }
diff --git a/src/main/aciodrv/icca.h b/src/main/aciodrv/icca.h
index ddae29e..44424d9 100644
--- a/src/main/aciodrv/icca.h
+++ b/src/main/aciodrv/icca.h
@@ -6,17 +6,19 @@
 /**
  * Initialize an ICCA node.
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to initialize (0 based).
  * @return True if successful, false on error.
  * @note This module is supposed to be used in combination with the common
  *       device driver foundation.
  * @see driver.h
  */
-bool aciodrv_icca_init(uint8_t node_id);
+bool aciodrv_icca_init(struct aciodrv_device_ctx *device, uint8_t node_id);
 
 /**
  * Set the state of on ICCA node.
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to set the state for (0 based).
  * @param slot_state State of the slot (refer to corresponding enum).
  * @param state Pointer to a state struct to return the current state to
@@ -27,11 +29,14 @@ bool aciodrv_icca_init(uint8_t node_id);
  * @see driver.h
  */
 bool aciodrv_icca_set_state(
-    uint8_t node_id, int slot_state, struct ac_io_icca_state *state);
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id, int slot_state,
+    struct ac_io_icca_state *state);
 
 /**
  * Get the current state of an ICCA node.
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to query (0 based).
  * @param state Pointer to a state struct to return the current state to
  *        (optional, NULL for none).
@@ -40,7 +45,10 @@ bool aciodrv_icca_set_state(
  *       device driver foundation.
  * @see driver.h
  */
-bool aciodrv_icca_get_state(uint8_t node_id, struct ac_io_icca_state *state);
+bool aciodrv_icca_get_state(
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id,
+    struct ac_io_icca_state *state);
 
 /**
  * Trigger a card read action on the ICCA reader. Make sure to call this
@@ -48,6 +56,7 @@ bool aciodrv_icca_get_state(uint8_t node_id, struct ac_io_icca_state *state);
  * to get the most recent card data. Make sure to re-get the state after
  * a read call. The state returned here might not be up to date for some reason.
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to query (0 based).
  * @param state Pointer to a state struct to return the current state to
  *        (optional, NULL for none).
@@ -56,6 +65,9 @@ bool aciodrv_icca_get_state(uint8_t node_id, struct ac_io_icca_state *state);
  *       device driver foundation.
  * @see driver.h
  */
-bool aciodrv_icca_read_card(uint8_t node_id, struct ac_io_icca_state *state);
+bool aciodrv_icca_read_card(
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id,
+    struct ac_io_icca_state *state);
 
 #endif
\ No newline at end of file
diff --git a/src/main/aciodrv/kfca.c b/src/main/aciodrv/kfca.c
index 000656f..9a3a93f 100644
--- a/src/main/aciodrv/kfca.c
+++ b/src/main/aciodrv/kfca.c
@@ -7,7 +7,9 @@
 
 #include "util/log.h"
 
-static bool aciodrv_kfca_watchdog_start(uint8_t node_id)
+static bool aciodrv_kfca_watchdog_start(
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id)
 {
     // exit early and don't actually call watchdog
     // the watchdog call actually returns different sized packets depending on
@@ -26,8 +28,9 @@ static bool aciodrv_kfca_watchdog_start(uint8_t node_id)
     msg.cmd.raw[0] = 23;
     msg.cmd.raw[1] = 112;
 
-    if (!aciodrv_send_and_recv(&msg, offsetof(struct ac_io_message, cmd.raw) +
-    2)) { log_warning("Starting watchdog failed"); return false;
+    if (!aciodrv_send_and_recv(
+            device, &msg, offsetof(struct ac_io_message, cmd.raw) + 2)) {
+        log_warning("Starting watchdog failed"); return false;
     }
 
     log_warning("Started watchdog of node %d, status: %d",
@@ -38,6 +41,7 @@ static bool aciodrv_kfca_watchdog_start(uint8_t node_id)
 }
 
 bool aciodrv_kfca_amp(
+    struct aciodrv_device_ctx *device,
     uint8_t node_id,
     uint8_t primary,
     uint8_t headphone,
@@ -56,7 +60,9 @@ bool aciodrv_kfca_amp(
     msg.cmd.raw[3] = subwoofer;
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + 1)) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + 1)) {
         log_warning("Setting AMP failed");
         return false;
     }
@@ -66,13 +72,15 @@ bool aciodrv_kfca_amp(
     return true;
 }
 
-bool aciodrv_kfca_init(uint8_t node_id)
+bool aciodrv_kfca_init(
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id)
 {
-    if (!aciodrv_kfca_watchdog_start(node_id)) {
+    if (!aciodrv_kfca_watchdog_start(device, node_id)) {
         return false;
     }
 
-    if (!aciodrv_kfca_amp(node_id, 0, 0, 0, 0)) {
+    if (!aciodrv_kfca_amp(device, node_id, 0, 0, 0, 0)) {
         return false;
     }
 
@@ -80,6 +88,7 @@ bool aciodrv_kfca_init(uint8_t node_id)
 }
 
 bool aciodrv_kfca_poll(
+    struct aciodrv_device_ctx *device,
     uint8_t node_id,
     const struct ac_io_kfca_poll_out *pout,
     struct ac_io_kfca_poll_in *pin)
@@ -93,7 +102,9 @@ bool aciodrv_kfca_poll(
     msg.cmd.kfca_poll_out = *pout;
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + sizeof(*pin))) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + sizeof(*pin))) {
         log_warning("Polling of node %d failed", node_id + 1);
         return false;
     }
diff --git a/src/main/aciodrv/kfca.h b/src/main/aciodrv/kfca.h
index 9f146bd..d73f259 100644
--- a/src/main/aciodrv/kfca.h
+++ b/src/main/aciodrv/kfca.h
@@ -6,17 +6,19 @@
 /**
  * Initialize an KFCA node.
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to initialize (0 based).
  * @return True if successful, false on error.
  * @note This module is supposed to be used in combination with the common
  *       device driver foundation.
  * @see driver.h
  */
-bool aciodrv_kfca_init(uint8_t node_id);
+bool aciodrv_kfca_init(struct aciodrv_device_ctx *device, uint8_t node_id);
 
 /**
  * Poll the KFCA io board
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to query (0 based).
  * @param state Pointer to a state struct to return the current state to
  *        (optional, NULL for none).
@@ -26,6 +28,7 @@ bool aciodrv_kfca_init(uint8_t node_id);
  * @see driver.h
  */
 bool aciodrv_kfca_poll(
+    struct aciodrv_device_ctx *device,
     uint8_t node_id,
     const struct ac_io_kfca_poll_out *pout,
     struct ac_io_kfca_poll_in *pin);
@@ -33,6 +36,7 @@ bool aciodrv_kfca_poll(
 /**
  * Set the KFCA digital amp level
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to query (0 based).
  * @param primary primary volume (96-0)
  * @param headphone headphone volume (96-0)
@@ -42,6 +46,7 @@ bool aciodrv_kfca_poll(
  * @note Note 96 (or 100?) is lowest volume level, 0 is highest
  */
 bool aciodrv_kfca_amp(
+    struct aciodrv_device_ctx *device,
     uint8_t node_id,
     uint8_t primary,
     uint8_t headphone,
diff --git a/src/main/aciodrv/port.c b/src/main/aciodrv/port.c
index 29c28b5..415cc4f 100644
--- a/src/main/aciodrv/port.c
+++ b/src/main/aciodrv/port.c
@@ -7,17 +7,15 @@
 
 #include "util/log.h"
 
-static HANDLE aciodrv_port_fd;
-
-bool aciodrv_port_open(const char *port, int baud)
+HANDLE aciodrv_port_open(const char *port_path, int baud)
 {
     COMMTIMEOUTS ct;
     DCB dcb;
 
-    log_info("Opening ACIO on %s at %d baud", port, baud);
+    log_info("Opening ACIO on %s at %d baud", port_path, baud);
 
-    aciodrv_port_fd = CreateFile(
-        port,
+    HANDLE port_fd = CreateFile(
+        port_path,
         GENERIC_READ | GENERIC_WRITE,
         0,
         NULL,
@@ -25,26 +23,26 @@ bool aciodrv_port_open(const char *port, int baud)
         FILE_FLAG_WRITE_THROUGH | FILE_ATTRIBUTE_NORMAL,
         NULL);
 
-    if (aciodrv_port_fd == INVALID_HANDLE_VALUE) {
-        log_warning("Failed to open %s", port);
+    if (port_fd == INVALID_HANDLE_VALUE) {
+        log_warning("Failed to open %s", port_path);
 
         goto early_fail;
     }
 
-    if (!SetCommMask(aciodrv_port_fd, EV_RXCHAR)) {
+    if (!SetCommMask(port_fd, EV_RXCHAR)) {
         log_warning("SetCommMask failed");
 
         goto fail;
     }
 
-    if (!SetupComm(aciodrv_port_fd, 0x1000, 0x1000)) {
+    if (!SetupComm(port_fd, 0x1000, 0x1000)) {
         log_warning("SetupComm failed");
 
         goto fail;
     }
 
     if (!PurgeComm(
-            aciodrv_port_fd,
+            port_fd,
             PURGE_TXABORT | PURGE_RXABORT | PURGE_TXCLEAR | PURGE_RXCLEAR)) {
         log_warning("PurgeComm failed");
 
@@ -57,7 +55,7 @@ bool aciodrv_port_open(const char *port, int baud)
     ct.ReadTotalTimeoutMultiplier = 0;
     ct.WriteTotalTimeoutMultiplier = 0;
 
-    if (!SetCommTimeouts(aciodrv_port_fd, &ct)) {
+    if (!SetCommTimeouts(port_fd, &ct)) {
         log_warning("SetCommTimeouts failed");
 
         goto fail;
@@ -65,7 +63,7 @@ bool aciodrv_port_open(const char *port, int baud)
 
     dcb.DCBlength = sizeof(dcb);
 
-    if (!GetCommState(aciodrv_port_fd, &dcb)) {
+    if (!GetCommState(port_fd, &dcb)) {
         log_warning("GetCommState failed");
 
         goto fail;
@@ -90,45 +88,44 @@ bool aciodrv_port_open(const char *port, int baud)
     dcb.XonLim = 100;
     dcb.XoffLim = 100;
 
-    if (!SetCommState(aciodrv_port_fd, &dcb)) {
+    if (!SetCommState(port_fd, &dcb)) {
         log_warning("SetCommState failed");
 
         goto fail;
     }
 
-    if (!EscapeCommFunction(aciodrv_port_fd, SETDTR)) {
+    if (!EscapeCommFunction(port_fd, SETDTR)) {
         log_warning("SETDTR failed: err = %lu", GetLastError());
 
         goto fail;
     }
 
-    log_info("Opened ACIO device on %s", port);
+    log_info("Opened ACIO device on %s", port_path);
 
-    return true;
+    return port_fd;
 
 fail:
-    CloseHandle(aciodrv_port_fd);
+    CloseHandle(port_fd);
 
 early_fail:
-    aciodrv_port_fd = NULL;
-    return false;
+    return NULL;
 }
 
-int aciodrv_port_read(void *bytes, int nbytes)
+int aciodrv_port_read(HANDLE port_fd, void *bytes, int nbytes)
 {
     DWORD nread;
 
-    if (aciodrv_port_fd == NULL) {
+    if (port_fd == NULL) {
         return -1;
     }
 
-    if (!ClearCommError(aciodrv_port_fd, NULL, NULL)) {
+    if (!ClearCommError(port_fd, NULL, NULL)) {
         log_warning("ClearCommError failed");
 
         return -1;
     }
 
-    if (!ReadFile(aciodrv_port_fd, bytes, nbytes, &nread, NULL)) {
+    if (!ReadFile(port_fd, bytes, nbytes, &nread, NULL)) {
         log_warning("ReadFile failed: err = %lu", GetLastError());
 
         return -1;
@@ -137,15 +134,15 @@ int aciodrv_port_read(void *bytes, int nbytes)
     return nread;
 }
 
-int aciodrv_port_write(const void *bytes, int nbytes)
+int aciodrv_port_write(HANDLE port_fd, const void *bytes, int nbytes)
 {
     DWORD nwrit;
 
-    if (aciodrv_port_fd == NULL) {
+    if (port_fd == NULL) {
         return -1;
     }
 
-    if (!WriteFile(aciodrv_port_fd, bytes, nbytes, &nwrit, NULL)) {
+    if (!WriteFile(port_fd, bytes, nbytes, &nwrit, NULL)) {
         log_warning("WriteFile failed: err = %lu", GetLastError());
 
         return -1;
@@ -154,9 +151,9 @@ int aciodrv_port_write(const void *bytes, int nbytes)
     return nwrit;
 }
 
-void aciodrv_port_close(void)
+void aciodrv_port_close(HANDLE port_fd)
 {
-    if (aciodrv_port_fd != NULL) {
-        CloseHandle(aciodrv_port_fd);
+    if (port_fd != NULL) {
+        CloseHandle(port_fd);
     }
 }
diff --git a/src/main/aciodrv/port.h b/src/main/aciodrv/port.h
index f9a423f..29c3417 100644
--- a/src/main/aciodrv/port.h
+++ b/src/main/aciodrv/port.h
@@ -4,39 +4,45 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#include <windows.h>
+
 /**
  * Open a serial port for communication with a ACIO device.
  *
  * @param port Port the device is connected to (e.g. "COM1")
  * @param baud Baud rate for communication (e.g. 57600 for ICCA)
- * @return True if opening the com port was successful, false on error.
+ * @return HANDLE of the port, NULL on error
  * @note This will open and setup the com port, only.
  */
-bool aciodrv_port_open(const char *port, int baud);
+HANDLE aciodrv_port_open(const char *port_path, int baud);
 
 /**
  * Read data from the opened com port.
  *
+ * @param port_fd HANDLE of opened serial port
  * @param bytes Pointer to an allocated buffer to read the data into.
  * @param nbytes Number of bytes to read. Has to be less or equal the allocated
  *        buffer size.
  * @return Number of bytes read on success or -1 on error.
  */
-int aciodrv_port_read(void *bytes, int nbytes);
+int aciodrv_port_read(HANDLE port_fd, void *bytes, int nbytes);
 
 /**
  * Write data to the opened com port.
  *
+ * @param port_fd HANDLE of opened serial port
  * @param bytes Pointer to an allocated buffer with data to write.
  * @param nbytes Number of bytes to write. Has to be equal or less the size
  *        of the allocated buffer.
  * @return Number of bytes written on success or -1 on error.
  */
-int aciodrv_port_write(const void *bytes, int nbytes);
+int aciodrv_port_write(HANDLE port_fd, const void *bytes, int nbytes);
 
 /**
  * Close the previously opened com port.
+ * 
+ * @param port_fd HANDLE of opened serial port
  */
-void aciodrv_port_close(void);
+void aciodrv_port_close(HANDLE port_fd);
 
 #endif
\ No newline at end of file
diff --git a/src/main/acioemu/emu.c b/src/main/acioemu/emu.c
index 9603279..11cf35a 100644
--- a/src/main/acioemu/emu.c
+++ b/src/main/acioemu/emu.c
@@ -134,6 +134,7 @@ static HRESULT ac_io_emu_write(struct ac_io_emu *emu, struct irp *irp)
             break;
         }
 
+        // this supplies a single SOF byte per byte read
         ac_io_in_supply(&emu->in, NULL, 0);
         ac_io_out_consume_message(&emu->out);
     }
diff --git a/src/main/aciotest/bi2a-sdvx.c b/src/main/aciotest/bi2a-sdvx.c
index 8c7b9f2..1ac6f68 100644
--- a/src/main/aciotest/bi2a-sdvx.c
+++ b/src/main/aciotest/bi2a-sdvx.c
@@ -8,22 +8,24 @@
 
 #include "bio2drv/bi2a-sdvx.h"
 
-bool aciotest_bi2a_sdvx_handler_init(uint8_t node_id, void **ctx)
+bool aciotest_bi2a_sdvx_handler_init(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void **ctx)
 {
     *ctx = malloc(sizeof(uint32_t));
     *((uint32_t *) *ctx) = 0;
 
-    return bio2drv_bi2a_sdvx_init(node_id);
+    return bio2drv_bi2a_sdvx_init(device, node_id);
 }
 
-bool aciotest_bi2a_sdvx_handler_update(uint8_t node_id, void *ctx)
+bool aciotest_bi2a_sdvx_handler_update(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void *ctx)
 {
     struct bi2a_sdvx_state_in pin;
     struct bi2a_sdvx_state_out pout;
 
     memset(&pout, 0, sizeof(pout));
 
-    if (!bio2drv_bi2a_sdvx_poll(node_id, &pout, &pin)) {
+    if (!bio2drv_bi2a_sdvx_poll(device, node_id, &pout, &pin)) {
         return false;
     }
 
diff --git a/src/main/aciotest/bi2a-sdvx.h b/src/main/aciotest/bi2a-sdvx.h
index 59d4a2d..a52bda3 100644
--- a/src/main/aciotest/bi2a-sdvx.h
+++ b/src/main/aciotest/bi2a-sdvx.h
@@ -4,7 +4,11 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-bool aciotest_bi2a_sdvx_handler_init(uint8_t node_id, void **ctx);
-bool aciotest_bi2a_sdvx_handler_update(uint8_t node_id, void *ctx);
+#include "aciodrv/device.h"
+
+bool aciotest_bi2a_sdvx_handler_init(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void **ctx);
+bool aciotest_bi2a_sdvx_handler_update(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void *ctx);
 
 #endif
diff --git a/src/main/aciotest/handler.h b/src/main/aciotest/handler.h
index b4e46cf..98f2e4c 100644
--- a/src/main/aciotest/handler.h
+++ b/src/main/aciotest/handler.h
@@ -1,6 +1,8 @@
 #ifndef ACIOTEST_HANDLER_H
 #define ACIOTEST_HANDLER_H
 
+#include "aciodrv/device.h"
+
 static const uint8_t aciotest_handler_max = 16;
 
 /**
@@ -8,8 +10,10 @@ static const uint8_t aciotest_handler_max = 16;
  */
 struct aciotest_handler_node_handler {
     void *ctx;
-    bool (*init)(uint8_t node_id, void **ctx);
-    bool (*update)(uint8_t node_id, void *ctx);
+    bool (*init)(
+        struct aciodrv_device_ctx *device, uint8_t node_id, void **ctx);
+    bool (*update)(
+        struct aciodrv_device_ctx *device, uint8_t node_id, void *ctx);
 };
 
 #endif
\ No newline at end of file
diff --git a/src/main/aciotest/icca.c b/src/main/aciotest/icca.c
index ad00359..41fbbbf 100644
--- a/src/main/aciotest/icca.c
+++ b/src/main/aciotest/icca.c
@@ -5,29 +5,31 @@
 
 #include "aciodrv/icca.h"
 
-bool aciotest_icca_handler_init(uint8_t node_id, void **ctx)
+bool aciotest_icca_handler_init(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void **ctx)
 {
     *ctx = malloc(sizeof(uint32_t));
     *((uint32_t *) *ctx) = 0;
 
-    return aciodrv_icca_init(node_id);
+    return aciodrv_icca_init(device, node_id);
 }
 
-bool aciotest_icca_handler_update(uint8_t node_id, void *ctx)
+bool aciotest_icca_handler_update(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void *ctx)
 {
     if (*((uint32_t *) ctx) == 0) {
         *((uint32_t *) ctx) = 1;
 
         /* eject cards that were left in the reader */
         if (!aciodrv_icca_set_state(
-                node_id, AC_IO_ICCA_SLOT_STATE_EJECT, NULL)) {
+                device, node_id, AC_IO_ICCA_SLOT_STATE_EJECT, NULL)) {
             return false;
         }
     }
 
     struct ac_io_icca_state state;
 
-    if (!aciodrv_icca_get_state(node_id, &state)) {
+    if (!aciodrv_icca_get_state(device, node_id, &state)) {
         return false;
     }
 
@@ -61,7 +63,7 @@ bool aciotest_icca_handler_update(uint8_t node_id, void *ctx)
     /* eject card with "empty" key */
     if (state.key_state & AC_IO_ICCA_KEYPAD_MASK_EMPTY) {
         if (!aciodrv_icca_set_state(
-                node_id, AC_IO_ICCA_SLOT_STATE_EJECT, NULL)) {
+                device, node_id, AC_IO_ICCA_SLOT_STATE_EJECT, NULL)) {
             return false;
         }
     }
@@ -70,7 +72,7 @@ bool aciotest_icca_handler_update(uint8_t node_id, void *ctx)
     if (!(state.sensor_state & AC_IO_ICCA_SENSOR_MASK_BACK_ON) &&
         !(state.sensor_state & AC_IO_ICCA_SENSOR_MASK_FRONT_ON)) {
         if (!aciodrv_icca_set_state(
-                node_id, AC_IO_ICCA_SLOT_STATE_OPEN, NULL)) {
+                device, node_id, AC_IO_ICCA_SLOT_STATE_OPEN, NULL)) {
             return false;
         }
     }
@@ -79,11 +81,11 @@ bool aciotest_icca_handler_update(uint8_t node_id, void *ctx)
     if ((state.sensor_state & AC_IO_ICCA_SENSOR_MASK_BACK_ON) &&
         (state.sensor_state & AC_IO_ICCA_SENSOR_MASK_FRONT_ON)) {
         if (!aciodrv_icca_set_state(
-                node_id, AC_IO_ICCA_SLOT_STATE_CLOSE, NULL)) {
+                device, node_id, AC_IO_ICCA_SLOT_STATE_CLOSE, NULL)) {
             return false;
         }
 
-        if (!aciodrv_icca_read_card(node_id, NULL)) {
+        if (!aciodrv_icca_read_card(device, node_id, NULL)) {
             return false;
         }
     }
diff --git a/src/main/aciotest/icca.h b/src/main/aciotest/icca.h
index f91fae5..0e05fd2 100644
--- a/src/main/aciotest/icca.h
+++ b/src/main/aciotest/icca.h
@@ -4,7 +4,11 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-bool aciotest_icca_handler_init(uint8_t node_id, void **ctx);
-bool aciotest_icca_handler_update(uint8_t node_id, void *ctx);
+#include "aciodrv/device.h"
+
+bool aciotest_icca_handler_init(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void **ctx);
+bool aciotest_icca_handler_update(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void *ctx);
 
 #endif
\ No newline at end of file
diff --git a/src/main/aciotest/kfca.c b/src/main/aciotest/kfca.c
index e9f0ba9..aec20c2 100644
--- a/src/main/aciotest/kfca.c
+++ b/src/main/aciotest/kfca.c
@@ -8,15 +8,17 @@
 
 #include "aciodrv/kfca.h"
 
-bool aciotest_kfca_handler_init(uint8_t node_id, void **ctx)
+bool aciotest_kfca_handler_init(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void **ctx)
 {
     *ctx = malloc(sizeof(uint32_t));
     *((uint32_t *) *ctx) = 0;
 
-    return aciodrv_kfca_init(node_id);
+    return aciodrv_kfca_init(device, node_id);
 }
 
-bool aciotest_kfca_handler_update(uint8_t node_id, void *ctx)
+bool aciotest_kfca_handler_update(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void *ctx)
 {
     struct ac_io_kfca_poll_in pin;
     struct ac_io_kfca_poll_out pout;
@@ -28,7 +30,7 @@ bool aciotest_kfca_handler_update(uint8_t node_id, void *ctx)
     pout.gpio |= 1 << gpio_test_pin;
     pout.gpio = ac_io_u32(pout.gpio);
 
-    if (!aciodrv_kfca_poll(node_id, &pout, &pin)) {
+    if (!aciodrv_kfca_poll(device, node_id, &pout, &pin)) {
         return false;
     }
 
diff --git a/src/main/aciotest/kfca.h b/src/main/aciotest/kfca.h
index 30c3d73..95e9d2b 100644
--- a/src/main/aciotest/kfca.h
+++ b/src/main/aciotest/kfca.h
@@ -4,7 +4,11 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-bool aciotest_kfca_handler_init(uint8_t node_id, void **ctx);
-bool aciotest_kfca_handler_update(uint8_t node_id, void *ctx);
+#include "aciodrv/device.h"
+
+bool aciotest_kfca_handler_init(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void **ctx);
+bool aciotest_kfca_handler_update(
+    struct aciodrv_device_ctx *device, uint8_t node_id, void *ctx);
 
 #endif
diff --git a/src/main/aciotest/main.c b/src/main/aciotest/main.c
index bea7eba..4cddca8 100644
--- a/src/main/aciotest/main.c
+++ b/src/main/aciotest/main.c
@@ -70,14 +70,16 @@ int main(int argc, char **argv)
 
     log_to_writer(log_writer_stdout, NULL);
 
-    if (!aciodrv_device_open(argv[1], atoi(argv[2]))) {
+
+    struct aciodrv_device_ctx *device = aciodrv_device_open(argv[1], atoi(argv[2]));
+    if (!device) {
         printf("Opening acio device failed\n");
         return -1;
     }
 
     printf("Opening acio device successful\n");
 
-    uint8_t node_count = aciodrv_device_get_node_count();
+    uint8_t node_count = aciodrv_device_get_node_count(device);
     printf("Enumerated %d nodes\n", node_count);
 
     struct aciotest_handler_node_handler handler[aciotest_handler_max];
@@ -88,7 +90,7 @@ int main(int argc, char **argv)
 
     for (uint8_t i = 0; i < node_count; i++) {
         char product[4];
-        aciodrv_device_get_node_product_ident(i, product);
+        aciodrv_device_get_node_product_ident(device, i, product);
         printf(
             "> %d: %c%c%c%c\n",
             i + 1,
@@ -110,7 +112,7 @@ int main(int argc, char **argv)
 
     for (uint8_t i = 0; i < aciotest_handler_max; i++) {
         if (handler[i].init != NULL) {
-            if (!handler[i].init(i, &handler[i].ctx)) {
+            if (!handler[i].init(device, i, &handler[i].ctx)) {
                 printf("ERROR: Initializing node %d failed\n", i);
                 handler[i].update = NULL;
             }
@@ -129,7 +131,7 @@ int main(int argc, char **argv)
 
         for (uint8_t i = 0; i < aciotest_handler_max; i++) {
             if (handler[i].update != NULL) {
-                if (!handler[i].update(i, handler[i].ctx)) {
+                if (!handler[i].update(device, i, handler[i].ctx)) {
                     printf("ERROR: Updating node %d, removed from loop\n", i);
                     handler[i].update = NULL;
                     Sleep(5000);
diff --git a/src/main/bio2drv/bi2a-iidx.c b/src/main/bio2drv/bi2a-iidx.c
index 2f7a6e3..666f9d2 100644
--- a/src/main/bio2drv/bi2a-iidx.c
+++ b/src/main/bio2drv/bi2a-iidx.c
@@ -14,7 +14,9 @@
 // in all inputs and outputs (over sub IO) other than 14 keys to not work.
 static const uint8_t _BIO2DR_BI2A_IIDX_INIT_DATA = 0x2D;
 
-static bool bio2drv_bi2a_iidx_init_io(uint8_t node_id)
+static bool bio2drv_bi2a_iidx_init_io(
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id)
 {
     struct ac_io_message msg;
 
@@ -24,7 +26,9 @@ static bool bio2drv_bi2a_iidx_init_io(uint8_t node_id)
     msg.cmd.param = _BIO2DR_BI2A_IIDX_INIT_DATA;
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + 1)) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + 1)) {
         log_warning("Init node failed");
         return 0;
     }
@@ -34,7 +38,9 @@ static bool bio2drv_bi2a_iidx_init_io(uint8_t node_id)
     return 1;
 }
 
-static bool bio2drv_bi2a_iidx_watchdog_start(uint8_t node_id)
+static bool bio2drv_bi2a_iidx_watchdog_start(
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id)
 {
     // exit early and don't actually call watchdog
     // the watchdog call actually returns different sized packets depending on
@@ -54,7 +60,7 @@ static bool bio2drv_bi2a_iidx_watchdog_start(uint8_t node_id)
     msg.cmd.raw[1] = 112;
 
     if (!aciodrv_send_and_recv(
-        &msg, offsetof(struct ac_io_message, cmd.raw) + 2
+        device, &msg, offsetof(struct ac_io_message, cmd.raw) + 2
     )) {
         log_warning("Starting watchdog failed"); return false;
     }
@@ -66,13 +72,13 @@ static bool bio2drv_bi2a_iidx_watchdog_start(uint8_t node_id)
     */
 }
 
-bool bio2drv_bi2a_iidx_init(uint8_t node_id)
+bool bio2drv_bi2a_iidx_init(struct aciodrv_device_ctx *device, uint8_t node_id)
 {
-    if (!bio2drv_bi2a_iidx_init_io(node_id)) {
+    if (!bio2drv_bi2a_iidx_init_io(device, node_id)) {
         return false;
     }
 
-    if (!bio2drv_bi2a_iidx_watchdog_start(node_id)) {
+    if (!bio2drv_bi2a_iidx_watchdog_start(device, node_id)) {
         return false;
     }
 
@@ -80,6 +86,7 @@ bool bio2drv_bi2a_iidx_init(uint8_t node_id)
 }
 
 bool bio2drv_bi2a_iidx_poll(
+    struct aciodrv_device_ctx *device,
     uint8_t node_id,
     const struct bi2a_iidx_state_out *pout,
     struct bi2a_iidx_state_in *pin)
@@ -93,7 +100,9 @@ bool bio2drv_bi2a_iidx_poll(
     *(struct bi2a_iidx_state_out *) msg.cmd.raw = *pout;
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + sizeof(*pin))) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + sizeof(*pin))) {
         log_warning("Polling of node %d failed", node_id + 1);
         return false;
     }
diff --git a/src/main/bio2drv/bi2a-iidx.h b/src/main/bio2drv/bi2a-iidx.h
index 6ec62e0..f90ce78 100644
--- a/src/main/bio2drv/bi2a-iidx.h
+++ b/src/main/bio2drv/bi2a-iidx.h
@@ -1,22 +1,28 @@
 #ifndef BIO2DRV_BI2A_IIDX_H
 #define BIO2DRV_BI2A_IIDX_H
 
+#include "aciodrv/device.h"
+
 #include "bio2/bi2a-iidx.h"
 
 /**
  * Initialize a BI2A node.
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to initialize (0 based).
  * @return True if successful, false on error.
  * @note This module is supposed to be used in combination with the common
  *       device driver foundation.
  * @see driver.h
  */
-bool bio2drv_bi2a_iidx_init(uint8_t node_id);
+bool bio2drv_bi2a_iidx_init(
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id);
 
 /**
  * Poll the BI2A board
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to query (0 based).
  * @param state Pointer to a state struct to return the current state to
  *        (optional, NULL for none).
@@ -26,6 +32,7 @@ bool bio2drv_bi2a_iidx_init(uint8_t node_id);
  * @see driver.h
  */
 bool bio2drv_bi2a_iidx_poll(
+    struct aciodrv_device_ctx *device,
     uint8_t node_id,
     const struct bi2a_iidx_state_out *pout,
     struct bi2a_iidx_state_in *pin);
diff --git a/src/main/bio2drv/bi2a-sdvx.c b/src/main/bio2drv/bi2a-sdvx.c
index 0d1fc6d..f8b6b25 100644
--- a/src/main/bio2drv/bi2a-sdvx.c
+++ b/src/main/bio2drv/bi2a-sdvx.c
@@ -12,7 +12,7 @@
 static const uint8_t _BIO2DR_BI2A_SDVX_INIT_DATA = 0x3B;
 
 // this is probably InitIO
-static bool bio2drv_bi2a_sdvx_init_io(uint8_t node_id)
+static bool bio2drv_bi2a_sdvx_init_io(struct aciodrv_device_ctx *device, uint8_t node_id)
 {
     struct ac_io_message msg;
 
@@ -22,7 +22,9 @@ static bool bio2drv_bi2a_sdvx_init_io(uint8_t node_id)
     msg.cmd.param = _BIO2DR_BI2A_SDVX_INIT_DATA;
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + 1)) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + 1)) {
         log_warning("Init node failed");
         return 0;
     }
@@ -32,7 +34,7 @@ static bool bio2drv_bi2a_sdvx_init_io(uint8_t node_id)
     return 1;
 }
 
-static bool bio2drv_bi2a_sdvx_watchdog_start(uint8_t node_id)
+static bool bio2drv_bi2a_sdvx_watchdog_start(struct aciodrv_device_ctx *device, uint8_t node_id)
 {
     // exit early and don't actually call watchdog
     // the watchdog call actually returns different sized packets depending on
@@ -65,6 +67,7 @@ static bool bio2drv_bi2a_sdvx_watchdog_start(uint8_t node_id)
 }
 
 bool bio2drv_bi2a_sdvx_amp(
+    struct aciodrv_device_ctx *device,
     uint8_t node_id,
     uint8_t unused_1,
     uint8_t unused_2,
@@ -86,7 +89,9 @@ bool bio2drv_bi2a_sdvx_amp(
     msg.cmd.raw[3] = right;
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + 1)) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + 1)) {
         log_warning("Setting AMP failed");
         return false;
     }
@@ -96,17 +101,17 @@ bool bio2drv_bi2a_sdvx_amp(
     return true;
 }
 
-bool bio2drv_bi2a_sdvx_init(uint8_t node_id)
+bool bio2drv_bi2a_sdvx_init(struct aciodrv_device_ctx *device, uint8_t node_id)
 {
-    if (!bio2drv_bi2a_sdvx_init_io(node_id)) {
+    if (!bio2drv_bi2a_sdvx_init_io(device, node_id)) {
         return false;
     }
 
-    if (!bio2drv_bi2a_sdvx_watchdog_start(node_id)) {
+    if (!bio2drv_bi2a_sdvx_watchdog_start(device, node_id)) {
         return false;
     }
 
-    if (!bio2drv_bi2a_sdvx_amp(node_id, 0, 0, 0, 0)) {
+    if (!bio2drv_bi2a_sdvx_amp(device, node_id, 0, 0, 0, 0)) {
         return false;
     }
 
@@ -114,6 +119,7 @@ bool bio2drv_bi2a_sdvx_init(uint8_t node_id)
 }
 
 bool bio2drv_bi2a_sdvx_poll(
+    struct aciodrv_device_ctx *device,
     uint8_t node_id,
     const struct bi2a_sdvx_state_out *pout,
     struct bi2a_sdvx_state_in *pin)
@@ -127,7 +133,9 @@ bool bio2drv_bi2a_sdvx_poll(
     *(struct bi2a_sdvx_state_out *) msg.cmd.raw = *pout;
 
     if (!aciodrv_send_and_recv(
-            &msg, offsetof(struct ac_io_message, cmd.raw) + sizeof(*pin))) {
+            device,
+            &msg,
+            offsetof(struct ac_io_message, cmd.raw) + sizeof(*pin))) {
         log_warning("Polling of node %d failed", node_id + 1);
         return false;
     }
diff --git a/src/main/bio2drv/bi2a-sdvx.h b/src/main/bio2drv/bi2a-sdvx.h
index a68aa78..6186dec 100644
--- a/src/main/bio2drv/bi2a-sdvx.h
+++ b/src/main/bio2drv/bi2a-sdvx.h
@@ -1,22 +1,28 @@
-#ifndef BIO2DRV_BI2A_H
-#define BIO2DRV_BI2A_H
+#ifndef BIO2DRV_BI2A_SDVX_H
+#define BIO2DRV_BI2A_SDVX_H
+
+#include "aciodrv/device.h"
 
 #include "bio2/bi2a-sdvx.h"
 
 /**
  * Initialize a BI2A node.
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to initialize (0 based).
  * @return True if successful, false on error.
  * @note This module is supposed to be used in combination with the common
  *       device driver foundation.
  * @see driver.h
  */
-bool bio2drv_bi2a_sdvx_init(uint8_t node_id);
+bool bio2drv_bi2a_sdvx_init(
+    struct aciodrv_device_ctx *device,
+    uint8_t node_id);
 
 /**
  * Poll the  board
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to query (0 based).
  * @param state Pointer to a state struct to return the current state to
  *        (optional, NULL for none).
@@ -26,6 +32,7 @@ bool bio2drv_bi2a_sdvx_init(uint8_t node_id);
  * @see driver.h
  */
 bool bio2drv_bi2a_sdvx_poll(
+    struct aciodrv_device_ctx *device,
     uint8_t node_id,
     const struct bi2a_sdvx_state_out *pout,
     struct bi2a_sdvx_state_in *pin);
@@ -33,6 +40,7 @@ bool bio2drv_bi2a_sdvx_poll(
 /**
  * Set the BIO2 BI2A SDVX digital amp level
  *
+ * @param device Context of opened device
  * @param node_id Id of the node to query (0 based).
  * @param primary primary volume (96-0)
  * @param headphone headphone volume (96-0)
@@ -42,6 +50,7 @@ bool bio2drv_bi2a_sdvx_poll(
  * @note Note 96 is lowest volume level, 0 is highest
  */
 bool bio2drv_bi2a_sdvx_amp(
+    struct aciodrv_device_ctx *device,
     uint8_t node_id,
     uint8_t unused_1,
     uint8_t unused_2,
diff --git a/src/main/eamio-icca/eamio-icca.c b/src/main/eamio-icca/eamio-icca.c
index 00478a6..7fe6080 100644
--- a/src/main/eamio-icca/eamio-icca.c
+++ b/src/main/eamio-icca/eamio-icca.c
@@ -34,6 +34,8 @@ static const uint8_t eam_io_keypad_mappings[16] = {EAM_IO_KEYPAD_DECIMAL,
 
 static struct ac_io_icca_state eam_io_icca_state[2];
 
+static struct aciodrv_device_ctx *acio_device_ctx;
+
 void eam_io_set_loggers(
     log_formatter_t misc,
     log_formatter_t info,
@@ -46,13 +48,14 @@ void eam_io_set_loggers(
 bool eam_io_init(
     thread_create_t create, thread_join_t join, thread_destroy_t destroy)
 {
-    if (!aciodrv_device_open("COM1", 57600)) {
+    acio_device_ctx = aciodrv_device_open("COM1", 57600);
+    if (acio_device_ctx == NULL) {
         log_warning("Opening acio device on COM1 failed");
         return false;
     }
 
     for (uint8_t i = 0; i < 2; i++) {
-        if (!aciodrv_icca_init(i)) {
+        if (!aciodrv_icca_init(acio_device_ctx, i)) {
             log_warning("Initializing icca %d failed", i);
             return false;
         }
@@ -63,7 +66,7 @@ bool eam_io_init(
 
 void eam_io_fini(void)
 {
-    aciodrv_device_close();
+    aciodrv_device_close(acio_device_ctx);
 }
 
 uint16_t eam_io_get_keypad_state(uint8_t unit_no)
@@ -112,19 +115,20 @@ bool eam_io_card_slot_cmd(uint8_t unit_no, uint8_t cmd)
     switch (cmd) {
         case EAM_IO_CARD_SLOT_CMD_CLOSE:
             return aciodrv_icca_set_state(
-                unit_no, AC_IO_ICCA_SLOT_STATE_CLOSE, NULL);
+                acio_device_ctx, unit_no, AC_IO_ICCA_SLOT_STATE_CLOSE, NULL);
 
         case EAM_IO_CARD_SLOT_CMD_OPEN:
             return aciodrv_icca_set_state(
-                unit_no, AC_IO_ICCA_SLOT_STATE_OPEN, NULL);
+                acio_device_ctx, unit_no, AC_IO_ICCA_SLOT_STATE_OPEN, NULL);
 
         case EAM_IO_CARD_SLOT_CMD_EJECT:
             return aciodrv_icca_set_state(
-                unit_no, AC_IO_ICCA_SLOT_STATE_EJECT, NULL);
+                acio_device_ctx, unit_no, AC_IO_ICCA_SLOT_STATE_EJECT, NULL);
 
         case EAM_IO_CARD_SLOT_CMD_READ:
-            return aciodrv_icca_read_card(unit_no, NULL) &&
-                aciodrv_icca_get_state(unit_no, &eam_io_icca_state[unit_no]);
+            return aciodrv_icca_read_card(acio_device_ctx, unit_no, NULL) &&
+                aciodrv_icca_get_state(
+                    acio_device_ctx, unit_no, &eam_io_icca_state[unit_no]);
 
         default:
             break;
@@ -135,7 +139,8 @@ bool eam_io_card_slot_cmd(uint8_t unit_no, uint8_t cmd)
 
 bool eam_io_poll(uint8_t unit_no)
 {
-    return aciodrv_icca_get_state(unit_no, &eam_io_icca_state[unit_no]);
+    return aciodrv_icca_get_state(
+        acio_device_ctx, unit_no, &eam_io_icca_state[unit_no]);
 }
 
 const struct eam_io_config_api *eam_io_get_config_api(void)
diff --git a/src/main/iidxio-bio2/iidxio.c b/src/main/iidxio-bio2/iidxio.c
index e005b45..f2762cd 100644
--- a/src/main/iidxio-bio2/iidxio.c
+++ b/src/main/iidxio-bio2/iidxio.c
@@ -38,6 +38,8 @@ static struct bi2a_iidx_state_in pin_cur;
 static struct bi2a_iidx_state_out pout_staging;
 static struct bi2a_iidx_state_out pout_ready;
 
+static struct aciodrv_device_ctx *bio2_device_ctx;
+
 static bool _bio2_iidx_io_poll(
     const struct bi2a_iidx_state_out *pout, struct bi2a_iidx_state_in *pin)
 {
@@ -47,7 +49,7 @@ static bool _bio2_iidx_io_poll(
 
     processing_io = true;
 
-    if (!bio2drv_bi2a_iidx_poll(bio2_node_id, pout, pin)) {
+    if (!bio2drv_bi2a_iidx_poll(bio2_device_ctx, bio2_node_id, pout, pin)) {
         processing_io = false;
         return false;
     }
@@ -114,14 +116,15 @@ bool iidx_io_init(
         }
     }
 
-    if (!aciodrv_device_open(selected_port, config_bio2.baud)) {
+    bio2_device_ctx = aciodrv_device_open(selected_port, config_bio2.baud);
+    if (bio2_device_ctx == NULL) {
         log_info("Opening BIO2 device on [%s] failed", selected_port);
         return 0;
     }
 
     log_info("Opening BIO2 device on [%s] successful", selected_port);
 
-    uint8_t node_count = aciodrv_device_get_node_count();
+    uint8_t node_count = aciodrv_device_get_node_count(bio2_device_ctx);
     log_info("Enumerated %d nodes", node_count);
 
     bio2_node_id = -1;
@@ -129,7 +132,7 @@ bool iidx_io_init(
     for (uint8_t i = 0; i < node_count; i++) {
         char product[4];
 
-        aciodrv_device_get_node_product_ident(i, product);
+        aciodrv_device_get_node_product_ident(bio2_device_ctx, i, product);
         
         log_info(
             "> %d: %c%c%c%c\n",
@@ -150,7 +153,7 @@ bool iidx_io_init(
     if (bio2_node_id != -1) {
         log_warning("Using BI2A on node: %d", bio2_node_id);
 
-        if (!bio2drv_bi2a_iidx_init(bio2_node_id)) {
+        if (!bio2drv_bi2a_iidx_init(bio2_device_ctx, bio2_node_id)) {
             log_warning("Unable to start BI2A on node: %d", bio2_node_id);
             return false;
         }
diff --git a/src/main/sdvxio-bio2/sdvxio.c b/src/main/sdvxio-bio2/sdvxio.c
index 0405682..3174180 100644
--- a/src/main/sdvxio-bio2/sdvxio.c
+++ b/src/main/sdvxio-bio2/sdvxio.c
@@ -40,6 +40,8 @@ uint8_t wing_staging[12];
 struct bi2a_sdvx_state_out pout_staging;
 struct bi2a_sdvx_state_out pout_ready;
 
+static struct aciodrv_device_ctx *bio2_device_ctx;
+
 void sdvx_io_set_loggers(
     log_formatter_t misc,
     log_formatter_t info,
@@ -99,21 +101,22 @@ bool sdvx_io_init(
         }
     }
 
-    if (!aciodrv_device_open(selected_port, config_bio2.baud)) {
+    bio2_device_ctx = aciodrv_device_open(selected_port, config_bio2.baud);
+    if (bio2_device_ctx == NULL) {
         log_info("Opening BIO2 device on [%s] failed", selected_port);
         return 0;
     }
 
     log_info("Opening BIO2 device on [%s] successful", selected_port);
 
-    uint8_t node_count = aciodrv_device_get_node_count();
+    uint8_t node_count = aciodrv_device_get_node_count(bio2_device_ctx);
     log_info("Enumerated %d nodes", node_count);
 
     bio2_node_id = -1;
 
     for (uint8_t i = 0; i < node_count; i++) {
         char product[4];
-        aciodrv_device_get_node_product_ident(i, product);
+        aciodrv_device_get_node_product_ident(bio2_device_ctx, i, product);
         log_info(
             "> %d: %c%c%c%c\n",
             i,
@@ -133,7 +136,7 @@ bool sdvx_io_init(
     if (bio2_node_id != -1) {
         log_warning("Using BI2A on node: %d", bio2_node_id);
 
-        if (!bio2drv_bi2a_sdvx_init(bio2_node_id)) {
+        if (!bio2drv_bi2a_sdvx_init(bio2_device_ctx, bio2_node_id)) {
             log_warning("Unable to start BI2A on node: %d", bio2_node_id);
             return false;
         }
@@ -240,7 +243,7 @@ bool _bio2_sdvx_io_poll(
 
     processing_io = true;
 
-    if (!bio2drv_bi2a_sdvx_poll(bio2_node_id, pout, pin)) {
+    if (!bio2drv_bi2a_sdvx_poll(bio2_device_ctx, bio2_node_id, pout, pin)) {
         processing_io = false;
         return false;
     }
@@ -319,7 +322,7 @@ bool sdvx_io_set_amp_volume(
 
     // yes, the BIO2 doesn't allow control of the amps individually
     // so let's just set it so that people's ear's don't blow out
-    if (!bio2drv_bi2a_sdvx_amp(bio2_node_id, 0, 0, primary, primary)) {
+    if (!bio2drv_bi2a_sdvx_amp(bio2_device_ctx, bio2_node_id, 0, 0, primary, primary)) {
         return false;
     }
 
diff --git a/src/main/sdvxio-kfca/sdvxio.c b/src/main/sdvxio-kfca/sdvxio.c
index 41708e6..21f8709 100644
--- a/src/main/sdvxio-kfca/sdvxio.c
+++ b/src/main/sdvxio-kfca/sdvxio.c
@@ -37,6 +37,8 @@ static int16_t kfca_node_id;
 struct ac_io_kfca_poll_out pout_staging;
 struct ac_io_kfca_poll_out pout_ready;
 
+static struct aciodrv_device_ctx *acio_device_ctx;
+
 void sdvx_io_set_loggers(
     log_formatter_t misc,
     log_formatter_t info,
@@ -78,21 +80,22 @@ bool sdvx_io_init(
 
     cconfig_finit(config);
 
-    if (!aciodrv_device_open(config_kfca.port, config_kfca.baud)) {
+    acio_device_ctx = aciodrv_device_open(config_kfca.port, config_kfca.baud);
+    if (acio_device_ctx == NULL) {
         log_info("Opening acio device on [%s] failed", config_kfca.port);
         return 0;
     }
 
     log_info("Opening acio device successful");
 
-    uint8_t node_count = aciodrv_device_get_node_count();
+    uint8_t node_count = aciodrv_device_get_node_count(acio_device_ctx);
     log_info("Enumerated %d nodes", node_count);
 
     kfca_node_id = -1;
 
     for (uint8_t i = 0; i < node_count; i++) {
         char product[4];
-        aciodrv_device_get_node_product_ident(i, product);
+        aciodrv_device_get_node_product_ident(acio_device_ctx, i, product);
         log_info(
             "> %d: %c%c%c%c\n",
             i,
@@ -112,7 +115,7 @@ bool sdvx_io_init(
     if (kfca_node_id != -1) {
         log_warning("Using KFCA on node: %d", kfca_node_id);
 
-        if (!aciodrv_kfca_init(kfca_node_id)) {
+        if (!aciodrv_kfca_init(acio_device_ctx, kfca_node_id)) {
             log_warning("Unable to start KFCA on node: %d", kfca_node_id);
             return false;
         }
@@ -163,7 +166,7 @@ bool sdvx_io_read_input(void)
     }
     processing_io = true;
 
-    if (!aciodrv_kfca_poll(kfca_node_id, &pout_ready, &pin)) {
+    if (!aciodrv_kfca_poll(acio_device_ctx, kfca_node_id, &pout_ready, &pin)) {
         return false;
     }
 
@@ -217,7 +220,10 @@ bool sdvx_io_set_amp_volume(
         return false;
     }
 
-    if (!aciodrv_kfca_amp(kfca_node_id, primary, 96, headphone, subwoofer)) {
+    if (!aciodrv_kfca_amp(
+            acio_device_ctx,
+            kfca_node_id,
+            primary, 96, headphone, subwoofer)) {
         return false;
     }