Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -r1d4d52365189e2cc83b97d28761bc2d4f0128859 -rc9eae083ca9c06f843ce7ebd7ef93ff47a986011
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 1d4d52365189e2cc83b97d28761bc2d4f0128859)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision c9eae083ca9c06f843ce7ebd7ef93ff47a986011)
@@ -1444,14 +1444,14 @@
 {
     BOOL result;
     MESSAGE_T msg;
-    U08 *payloadPtr = msg.payload;
+    DG_VALVE_SETTING_CMD_REQUEST_T valveCmd;
 
     // Create a message record
     blankMessage( &msg );
     msg.hdr.msgID = MSG_ID_DG_CHANGE_VALVE_SETTING_CMD_REQUEST;
-    msg.hdr.payloadLen = sizeof( U32 );
+    msg.hdr.payloadLen = sizeof( DG_VALVE_SETTING_CMD_REQUEST_T );
 
-    memcpy( payloadPtr, &valveSettingCmd, sizeof( U32 ) );
+    memcpy( &msg.payload, &valveCmd, sizeof( DG_VALVE_SETTING_CMD_REQUEST_T ) );
 
     // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
     result = serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_DG, ACK_REQUIRED );
@@ -1474,19 +1474,18 @@
 {
     BOOL result;
     MESSAGE_T msg;
-    U08 *payloadPtr = msg.payload;
+    DG_FILL_CMD_T fillPayload;
 
+    fillPayload.fillToVolMl = fillToVolumeMl;
+    fillPayload.cmd = cmd;
+    fillPayload.targetFlowRateLPM = targetFlowRateLPM;
+
     // Create a message record
     blankMessage( &msg );
     msg.hdr.msgID = MSG_ID_DG_FILL_CMD_REQUEST;
-    msg.hdr.payloadLen = sizeof( U32 ) + sizeof( U32 ) + sizeof( F32 );
+    msg.hdr.payloadLen = sizeof( DG_FILL_CMD_T );
+    memcpy( &msg.payload, &fillPayload, sizeof( DG_FILL_CMD_T ) );
 
-    memcpy( payloadPtr, &fillToVolumeMl, sizeof( U32 ) );
-    payloadPtr += sizeof( U32 );
-    memcpy( payloadPtr, &cmd, sizeof( U32 ) );
-    payloadPtr += sizeof( F32 );
-    memcpy( payloadPtr, &targetFlowRateLPM, sizeof( F32 ) );
-
     // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
     result = serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_DG, ACK_REQUIRED );
 
@@ -1534,14 +1533,16 @@
 {
     BOOL result;
     MESSAGE_T msg;
-    U08 *payloadPtr = msg.payload;
+    DG_START_STOP_TX_CMD_REQUEST_T cmd;
 
+    cmd.start = start;
+
     // Create a message record
     blankMessage( &msg );
     msg.hdr.msgID = MSG_ID_STARTING_STOPPING_TREATMENT_CMD_REQUEST;
-    msg.hdr.payloadLen = sizeof( BOOL );
+    msg.hdr.payloadLen = sizeof( DG_START_STOP_TX_CMD_REQUEST_T );
 
-    memcpy( payloadPtr, &start, sizeof( BOOL ) );
+    memcpy( &msg.payload, &cmd, sizeof( DG_START_STOP_TX_CMD_REQUEST_T ) );
 
     // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
     result = serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_DG, ACK_REQUIRED );
@@ -1563,14 +1564,16 @@
 {
     BOOL result;
     MESSAGE_T msg;
-    U08 *payloadPtr = msg.payload;
+    DG_START_STOP_TRIMMER_HEATER_CMD_T cmd;
 
+    cmd.start = start;
+
     // Create a message record
     blankMessage( &msg );
     msg.hdr.msgID = MSG_ID_HD_START_STOP_TRIMMER_HEATER_CMD_REQUEST;
-    msg.hdr.payloadLen = sizeof( BOOL );
+    msg.hdr.payloadLen = sizeof( DG_START_STOP_TRIMMER_HEATER_CMD_T );
 
-    memcpy( payloadPtr, &start, sizeof( BOOL ) );
+    memcpy( &msg.payload, &cmd, sizeof( DG_START_STOP_TRIMMER_HEATER_CMD_T ) );
 
     // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
     result = serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_DG, ACK_REQUIRED );
@@ -1595,9 +1598,9 @@
     // Create a message record
     blankMessage( &msg );
     msg.hdr.msgID = MSG_ID_DG_SAMPLE_WATER_CMD_REQUEST;
-    msg.hdr.payloadLen = sizeof( U32 );
+    msg.hdr.payloadLen = sizeof( SAMPLE_WATER_CMD_T );
 
-    memcpy( msg.payload, &cmd, sizeof( U32 ) );
+    memcpy( &msg.payload, &cmd, sizeof( SAMPLE_WATER_CMD_T ) );
 
     // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
     result = serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_DG, ACK_REQUIRED );
@@ -1712,13 +1715,16 @@
 {
     BOOL result;
     MESSAGE_T msg;
+    DG_FLUSH_MODE_CMD_T cmd;
 
+    cmd.start = start;
+
     // Create a message record
     blankMessage( &msg );
     msg.hdr.msgID = MSG_ID_DG_START_STOP_FLUSH_CMD_REQUEST;
-    msg.hdr.payloadLen = sizeof( BOOL );
+    msg.hdr.payloadLen = sizeof( DG_FLUSH_MODE_CMD_T );
 
-    memcpy( msg.payload, &start, sizeof( BOOL ) );
+    memcpy( &msg.payload, &cmd, sizeof( DG_FLUSH_MODE_CMD_T ) );
 
     // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
     result = serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_DG, ACK_REQUIRED );
@@ -1741,13 +1747,16 @@
 {
     BOOL result;
     MESSAGE_T msg;
+    DG_HEAT_DISINFECTION_MODE_CMD_T cmd;
 
+    cmd.start = start;
+
     // Create a message record
     blankMessage( &msg );
     msg.hdr.msgID = MSG_ID_DG_START_STOP_HEAT_DISINFECT_CMD_REQUEST;
-    msg.hdr.payloadLen = sizeof( BOOL );
+    msg.hdr.payloadLen = sizeof( DG_HEAT_DISINFECTION_MODE_CMD_T );
 
-    memcpy( msg.payload, &start, sizeof( BOOL ) );
+    memcpy( &msg.payload, &start, sizeof( DG_HEAT_DISINFECTION_MODE_CMD_T ) );
 
     // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
     result = serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_DG, ACK_REQUIRED );
@@ -1774,9 +1783,9 @@
     // Create a message record
     blankMessage( &msg );
     msg.hdr.msgID = MSG_ID_DG_START_STOP_CHEM_DISINFECT;
-    msg.hdr.payloadLen = sizeof( BOOL );
+    msg.hdr.payloadLen = sizeof( DG_CHEM_DISINFECTION_MODE_CMD_T );
 
-    memcpy( msg.payload, &start, sizeof( BOOL ) );
+    memcpy( &msg.payload, &start, sizeof( DG_CHEM_DISINFECTION_MODE_CMD_T ) );
 
     // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
     result = serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_DG, ACK_REQUIRED );
Index: firmware/App/Services/SystemCommMessages.h
===================================================================
diff -u -rea731c287a4e43901956aaa9a0009a5ee8f4671f -rc9eae083ca9c06f843ce7ebd7ef93ff47a986011
--- firmware/App/Services/SystemCommMessages.h	(.../SystemCommMessages.h)	(revision ea731c287a4e43901956aaa9a0009a5ee8f4671f)
+++ firmware/App/Services/SystemCommMessages.h	(.../SystemCommMessages.h)	(revision c9eae083ca9c06f843ce7ebd7ef93ff47a986011)
@@ -64,32 +64,23 @@
 #define ACK_REQUIRED                    TRUE                ///< Macro for functions that want to know if an outgoing message requires acknowledgement from receiver.
 #define ACK_NOT_REQUIRED                FALSE               ///< Macro for functions that want to know if an outgoing message requires acknowledgement from receiver.
 
-
-
+#pragma pack(push, 1)
 typedef struct
 {
     U08 acknowledgement;         ///< Acknowledgement Byte
 } ACK_RESPONSE_PAYLOAD_T;
 
 typedef struct
 {
-    BOOL accepted;              ///< Accepted/Rejected
-    U32 rejectionReason;        ///< Rejection reason if not accepted.
-} UI_RESPONSE_PAYLOAD_T;
-
-typedef struct
-{
     U08 userRequest;            ///< request to confirm, cancel, or reject off button request
 } UI_OFF_BUTTON_RESPONSE_PAYLOAD_T;
+#pragma pack(pop)
 
 typedef struct
 {
-    U32 event;                  ///< Event ID
-    U32 dataType1;              ///< Data type for data field 1
-    EVENT_DATAS_T data1;        ///< data field 1
-    U32 dataType2;              ///< Data type for data field 2
-    EVENT_DATAS_T data2;        ///< Data field 2
-} EVENT_PAYLOAD_T;
+    BOOL accepted;              ///< Accepted/Rejected
+    U32 rejectionReason;        ///< Rejection reason if not accepted.
+} UI_RESPONSE_PAYLOAD_T;
 
 typedef struct
 {
@@ -130,6 +121,15 @@
 
 typedef struct
 {
+    U32 event;                  ///< Event ID
+    U32 dataType1;              ///< Data type for data field 1
+    EVENT_DATAS_T data1;        ///< data field 1
+    U32 dataType2;              ///< Data type for data field 2
+    EVENT_DATAS_T data2;        ///< Data field 2
+} EVENT_PAYLOAD_T;
+
+typedef struct
+{
     U32 minTreatmentTime;       ///< Minimum treatment duration (in minutes)
     U32 maxTreatmentTime;       ///< Maximum treatment duration (in minutes)
     F32 minUFVolume;            ///< Minimum ultrafiltration volume (in mL)