Index: leahi_dialin/dd/modules/piston_pump.py
===================================================================
diff -u -re7d16bd6881619e5fc2a0bc1a7fd578a9978498e -rd9c41496bfba02f66b6b38a8ecae8c017f160235
--- leahi_dialin/dd/modules/piston_pump.py	(.../piston_pump.py)	(revision e7d16bd6881619e5fc2a0bc1a7fd578a9978498e)
+++ leahi_dialin/dd/modules/piston_pump.py	(.../piston_pump.py)	(revision d9c41496bfba02f66b6b38a8ecae8c017f160235)
@@ -155,7 +155,7 @@
         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,