Index: firmware/App/HDCommon.h
===================================================================
diff -u -r116e7a0b38092b9272396b9d7dab112b4e9a3441 -r92f32196d272e32f9480e82dd09a038bb68753bc
--- firmware/App/HDCommon.h	(.../HDCommon.h)	(revision 116e7a0b38092b9272396b9d7dab112b4e9a3441)
+++ firmware/App/HDCommon.h	(.../HDCommon.h)	(revision 92f32196d272e32f9480e82dd09a038bb68753bc)
@@ -35,6 +35,7 @@
 //    #define BOARD_WITH_NO_HARDWARE          1           // Target is a PCB w/ no hardware
 //    #define SIMULATE_UI                     1           // Build w/o requirement that UI be there
 //    #define TASK_TIMING_OUTPUT_ENABLED      1           // Re-purposes alarm lamp pins for task timing
+    #define CARTRIDGE_TEST_BUILD            1           // Build to support cartridge testing
 
     #include <stdio.h>
     #include <strings.h>
Index: firmware/App/Modes/ModeStandby.c
===================================================================
diff -u -ra1a0187daedaf2c12e6f9eccfbf9e423d952e029 -r92f32196d272e32f9480e82dd09a038bb68753bc
--- firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision a1a0187daedaf2c12e6f9eccfbf9e423d952e029)
+++ firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision 92f32196d272e32f9480e82dd09a038bb68753bc)
@@ -77,6 +77,10 @@
 /// Interval (in task intervals) at which to publish standby mode data to CAN bus.
 static OVERRIDE_U32_T standbyModePublishInterval = { DISINFECTS_DATA_PUB_INTERVAL, DISINFECTS_DATA_PUB_INTERVAL, DISINFECTS_DATA_PUB_INTERVAL, 0 };
 
+#ifdef CARTRIDGE_TEST_BUILD
+static BOOL testCartridgesMode = FALSE; // Flag indicates we are testing cartridges.  Used only for cartridge test build.
+#endif
+
 // ********** private function prototypes **********
 
 static HD_STANDBY_STATE_T handleStandbyModeStartState( void );
@@ -231,6 +235,36 @@
             break;
     }
 
+#ifdef CARTRIDGE_TEST_BUILD
+    if ( TRUE == stop )
+    {
+        if ( testCartridgesMode != TRUE )
+        {
+            testSetBloodPumpTargetDutyCycle( 0.652F );
+            testSetDialInPumpTargetDutyCycle( 0.701F );
+            testSetDialOutPumpTargetDutyCycle( 0.566F );
+            setValvePosition( VDI, VALVE_POSITION_B_OPEN );
+            setValvePosition( VDO, VALVE_POSITION_B_OPEN );
+            setValvePosition( VBA, VALVE_POSITION_B_OPEN );
+            setValvePosition( VBV, VALVE_POSITION_B_OPEN );
+            setValveAirTrap( STATE_CLOSED );
+            testCartridgesMode = TRUE;
+        }
+        else
+        {
+            signalBloodPumpHardStop();
+            signalDialInPumpHardStop();
+            signalDialOutPumpHardStop();
+            setValvePosition( VDI, VALVE_POSITION_A_INSERT_EJECT );
+            setValvePosition( VDO, VALVE_POSITION_A_INSERT_EJECT );
+            setValvePosition( VBA, VALVE_POSITION_A_INSERT_EJECT );
+            setValvePosition( VBV, VALVE_POSITION_A_INSERT_EJECT );
+            setValveAirTrap( STATE_OPEN );
+            testCartridgesMode = FALSE;
+        }
+    }
+#endif
+
     return currentStandbyState;
 }
 
Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -refead43ba16292aa173f72ebfa2b73aebfd2a587 -r92f32196d272e32f9480e82dd09a038bb68753bc
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision efead43ba16292aa173f72ebfa2b73aebfd2a587)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 92f32196d272e32f9480e82dd09a038bb68753bc)
@@ -96,7 +96,11 @@
 
 // ********** private data **********
 
+#ifndef CARTRIDGE_TEST_BUILD
 static BOOL testerLoggedIn = FALSE;                         ///< Flag indicates whether an external tester (connected PC) has sent a valid login message.
+#else
+static BOOL testerLoggedIn = TRUE;                          ///< Flag indicates whether an external tester (connected PC) has sent a valid login message.
+#endif
 static volatile U16 nextSeqNo = 1;                          ///< Value of sequence number to use for next transmitted message.
 
 /// List of message IDs that are requested not to be transmitted.