Index: leahi_dialin/dd/modules/piston_pump.py
===================================================================
diff -u -r68422d08c4141999a13496343264483a32314d37 -rfe37f0a0f2c683696f41f6a349cf2756ed09d5d7
--- leahi_dialin/dd/modules/piston_pump.py	(.../piston_pump.py)	(revision 68422d08c4141999a13496343264483a32314d37)
+++ leahi_dialin/dd/modules/piston_pump.py	(.../piston_pump.py)	(revision fe37f0a0f2c683696f41f6a349cf2756ed09d5d7)
@@ -153,7 +153,7 @@
         cyc = integer_to_bytearray(count)
         spd = float_to_bytearray(flow_rate)
         vlm = float_to_bytearray(volume)
-        payload = pmp + cmd + cyc + spd + vlm
+        payload = pmp + cmd + cyc + vlm + spd
 
         message = DenaliMessage.build_message(channel_id=DenaliChannels.dialin_to_dd_ch_id,
                                               message_id=MsgIds.MSG_ID_DD_PISTON_PUMP_START_STOP_OVERRIDE_REQUEST.value,