Index: dialin/hd/blood_flow.py
===================================================================
diff -u -r4bdb012848d1b59be5edc31d677b77b9d95f6190 -r248e2e2c3799d8236da9178ba5c4fd5e51b25776
--- dialin/hd/blood_flow.py	(.../blood_flow.py)	(revision 4bdb012848d1b59be5edc31d677b77b9d95f6190)
+++ dialin/hd/blood_flow.py	(.../blood_flow.py)	(revision 248e2e2c3799d8236da9178ba5c4fd5e51b25776)
@@ -174,18 +174,20 @@
         self.measured_blood_pump_mc_current = mccurr[0]
         self.pwm_duty_cycle_pct = pwm[0]
 
-    def cmd_blood_flow_set_point_override(self, flow, reset=NO_RESET):
+    def cmd_blood_flow_set_point_override(self, flow, mode, reset=NO_RESET):
         """
         Constructs and sends the blood flow set point override command
 
         @param flow:  integer - flow set point (in mL/min) to override with (negative for reverse direction)
+        @param mode:  integer - 0 for closed loop control mode and 1 for open loop control mode
         @param reset:  integer - 1 to reset a previous override, 0 to override
         @return: 1 if successful, zero otherwise
         """
 
         rst = integer_to_bytearray(reset)
         flo = integer_to_bytearray(flow)
-        payload = rst + flo
+        mod = integer_to_bytearray(mode)
+        payload = rst + flo + mod
 
         message = DenaliMessage.build_message(channel_id=DenaliChannels.dialin_to_hd_ch_id,
                                               message_id=self.MSG_ID_HD_BLOOD_FLOW_SET_RATE_OVERRIDE,
Index: tests/hd_test_pumps_open_loop.py
===================================================================
diff -u -r31e54f25bc55ee863fbec78bc23dabdaac30e114 -r248e2e2c3799d8236da9178ba5c4fd5e51b25776
--- tests/hd_test_pumps_open_loop.py	(.../hd_test_pumps_open_loop.py)	(revision 31e54f25bc55ee863fbec78bc23dabdaac30e114)
+++ tests/hd_test_pumps_open_loop.py	(.../hd_test_pumps_open_loop.py)	(revision 248e2e2c3799d8236da9178ba5c4fd5e51b25776)
@@ -38,8 +38,8 @@
 
         # Set HD open loop pumps flow rates in mL/min
         HD_BLOOD_PUMP_FLOW_RATE = 200
-        HD_DIALYSATE_PUMP_IN_FLOW_RATE = 200
-        HD_DIALYSATE_PUMP_OUT_FLOW_RATE = 200
+        #HD_DIALYSATE_PUMP_IN_FLOW_RATE = 200
+        #HD_DIALYSATE_PUMP_OUT_FLOW_RATE = 200
 
         # Log in to HD as tester
         if hd.cmd_log_in_to_hd() == 0:
@@ -50,44 +50,44 @@
         # Reset all flow rate broadcast intervals
         hd.bloodflow.cmd_blood_flow_broadcast_interval_override(RESET, 0)
         sleep(1)
-        hd.dialysate_inlet_flow.cmd_dialysate_inlet_flow_broadcast_interval_override(RESET, 0)
-        sleep(1)
-        hd.dialysate_outlet_flow.cmd_dialysate_outlet_flow_broadcast_interval_override(RESET, 0)
-        sleep(1)
+        #hd.dialysate_inlet_flow.cmd_dialysate_inlet_flow_broadcast_interval_override(RESET, 0)
+        #sleep(1)
+        #hd.dialysate_outlet_flow.cmd_dialysate_outlet_flow_broadcast_interval_override(RESET, 0)
+        #sleep(1)
 
         # Reset all flow rate set points
         hd.bloodflow.cmd_blood_flow_set_point_override(RESET, 0)
         sleep(1)
-        hd.dialysate_inlet_flow.cmd_dialysate_inlet_flow_set_point_override(RESET, 0)
-        sleep(1)
-        hd.dialysate_outlet_flow.cmd_dialysate_outlet_flow_set_point_override(RESET, 0)
-        sleep(1)
+        #hd.dialysate_inlet_flow.cmd_dialysate_inlet_flow_set_point_override(RESET, 0)
+        #sleep(1)
+        #hd.dialysate_outlet_flow.cmd_dialysate_outlet_flow_set_point_override(RESET, 0)
+        #sleep(1)
 
         # Reset all flow rate measures
         hd.bloodflow.cmd_blood_flow_measured_override(RESET, 0)
         sleep(1)
-        hd.dialysate_inlet_flow.cmd_dialysate_inlet_flow_measured_override(RESET, 0)
-        sleep(1)
-        hd.dialysate_outlet_flow.cmd_dialysate_outlet_flow_measured_override(RESET, 0)
-        sleep(1)
+        #hd.dialysate_inlet_flow.cmd_dialysate_inlet_flow_measured_override(RESET, 0)
+        #sleep(1)
+        #hd.dialysate_outlet_flow.cmd_dialysate_outlet_flow_measured_override(RESET, 0)
+        #sleep(1)
 
         # Set HD pumps flow rates (open loop)
         hd.bloodflow.cmd_blood_flow_set_point_override(HD_BLOOD_PUMP_FLOW_RATE, PUMP_CONTROL_MODE_OPEN_LOOP)
-        hd.dialysate_inlet_flow.cmd_dialysate_inlet_flow_set_point_override(HD_DIALYSATE_PUMP_IN_FLOW_RATE, PUMP_CONTROL_MODE_OPEN_LOOP)
-        hd.dialysate_outlet_flow.cmd_dialysate_outlet_flow_set_point_override(HD_DIALYSATE_PUMP_OUT_FLOW_RATE, PUMP_CONTROL_MODE_OPEN_LOOP)
+        #hd.dialysate_inlet_flow.cmd_dialysate_inlet_flow_set_point_override(HD_DIALYSATE_PUMP_IN_FLOW_RATE, PUMP_CONTROL_MODE_OPEN_LOOP)
+        #hd.dialysate_outlet_flow.cmd_dialysate_outlet_flow_set_point_override(HD_DIALYSATE_PUMP_OUT_FLOW_RATE, PUMP_CONTROL_MODE_OPEN_LOOP)
         sleep(5)
 
         print("Blood Flow Target = {}".format(hd.bloodflow.target_blood_flow_rate))
-        print("Dialysate Flow In Target = {}".format(hd.dialysate_inlet_flow.target_dialysate_inlet_flow_rate))
-        print("Dialysate Flow Out Target = {}".format(hd.dialysate_outlet_flow.target_dialysate_outlet_flow_rate))
+        #print("Dialysate Flow In Target = {}".format(hd.dialysate_inlet_flow.target_dialysate_inlet_flow_rate))
+        #print("Dialysate Flow Out Target = {}".format(hd.dialysate_outlet_flow.target_dialysate_outlet_flow_rate))
         sleep(1)
 
         i = 0
         while True:
             sleep(0.5)
             print("Measured Blood Flow = {} mL/min".format(hd.bloodflow.measured_blood_flow_rate))
-            print("Measured Dialysate Flow In = {} mL/min".format(hd.dialysate_inlet_flow.measured_dialysate_inlet_flow_rate))
-            print("Measured Dialysate Flow Out = {} mL/min".format(hd.dialysate_outlet_flow.measured_dialysate_outlet_flow_rate))
+            #print("Measured Dialysate Flow In = {} mL/min".format(hd.dialysate_inlet_flow.measured_dialysate_inlet_flow_rate))
+            #print("Measured Dialysate Flow Out = {} mL/min".format(hd.dialysate_outlet_flow.measured_dialysate_outlet_flow_rate))
             if i > 0 and i % 60 == 0:
                 resp = input("Press 'Enter' to continue or 'q' to quit: ")
                 if resp.lower() == "q":