Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -r1eac55db00559965a7dc6752fc42a2c54d56f4b9 -rabbad386f4cc94f315300dffef321fe8c03fbd52
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 1eac55db00559965a7dc6752fc42a2c54d56f4b9)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision abbad386f4cc94f315300dffef321fe8c03fbd52)
@@ -26,6 +26,7 @@
 #include "FPGA.h"
 #include "ModeStandby.h"
 #include "ModeTreatmentParams.h"
+#include "NVDataMgmt.h"
 #include "OperationModes.h"
 #include "RTC.h"
 #include "SampleWater.h"
@@ -3837,9 +3838,11 @@
 
 /*********************************************************************//**
  * @brief
- * The handleFWVersionRequest function handles a request for HD f/w version.
+ * The handleFWVersionRequest function handles a request for HD f/w
+ * version.
  * @details Inputs: none
- * @details Outputs: message handled, response constructed and queued for transmit.
+ * @details Outputs: message handled, response constructed and queued
+ * for transmit.
  * @param message a pointer to the message to handle.
  * @return none
  *************************************************************************/
@@ -3866,6 +3869,96 @@
 
     // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
     serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_UI, ACK_REQUIRED );
+}
+
+/*********************************************************************//**
+ * @brief
+ * The handleHDSerialNumberRequest function handles a request for HD serial
+ * number request.
+ * @details Inputs: none
+ * @details Outputs: message handled, response constructed and queued
+ * for transmit.
+ * @param message a pointer to the message to handle.
+ * @return none
+ *************************************************************************/
+void handleHDSerialNumberRequest( MESSAGE_T *message )
+{
+    MESSAGE_T msg;
+    HD_SYSTEM_RECORD_T system = getHDSystemRecord();
+    U08 *payloadPtr = msg.payload;
+
+    // Create a message record
+    blankMessage( &msg );
+    msg.hdr.msgID = MSG_ID_HD_SERIAL_NUMBER;
+
+    // Add 1 byte for null terminator
+    msg.hdr.payloadLen = MAX_TOP_LEVEL_SN_CHARS + 1;
+
+    // Fill message payload
+    memcpy( payloadPtr, &system.topLevelSN, MAX_TOP_LEVEL_SN_CHARS );
+    payloadPtr += MAX_TOP_LEVEL_SN_CHARS;
+    *payloadPtr = 0;
+
+    // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
+    serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_UI, ACK_REQUIRED );
+}
+
+/*********************************************************************//**
+ * @brief
+ * The handleHDServiceScheduleRequest function handles a request for HD
+ * service information.
+ * @details Inputs: none
+ * @details Outputs: message handled, response constructed and queued for
+ * transmit.
+ * @param message a pointer to the message to handle.
+ * @return none
+ *************************************************************************/
+void handleHDServiceScheduleRequest( MESSAGE_T *message )
+{
+    MESSAGE_T msg;
+    HD_SERVICE_RECORD_T payload = getHDServiceRecord();
+    U08 *payloadPtr = msg.payload;
+
+    // Create a message record
+    blankMessage( &msg );
+    msg.hdr.msgID = MSG_ID_HD_SERVICE_SCHEDULE_DATA;
+    msg.hdr.payloadLen = sizeof( U32 ) + sizeof( U32 );
+
+    // Fill message payload
+    memcpy( payloadPtr, &payload.lastServiceEpochDate, sizeof( U32 ) );
+    payloadPtr += sizeof( U32 );
+    memcpy( payloadPtr, &payload.serviceIntervalSeconds, sizeof( U32 ) );
+
+    // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
+    serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_UI, ACK_REQUIRED );
+}
+
+/*********************************************************************//**
+ * @brief
+ * The handleHDUsageInfoRequest function handles a request for HD
+ * usage information.
+ * @details Inputs: none
+ * @details Outputs: message handled, response constructed and queued for
+ * transmit.
+ * @param message a pointer to the message to handle.
+ * @return none
+ *************************************************************************/
+void handleHDUsageInfoRequest( MESSAGE_T *message )
+{
+    MESSAGE_T msg;
+    U32 payload = getTreatmentTime();
+    U08 *payloadPtr = msg.payload;
+
+    // Create a message record
+    blankMessage( &msg );
+    msg.hdr.msgID = MSG_ID_HD_USAGE_DATA;
+    msg.hdr.payloadLen = sizeof( U32 );
+
+    // Fill message payload
+    memcpy( payloadPtr, &payload, sizeof( U32 ) );
+
+    // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
+    serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_UI, ACK_REQUIRED );
 }