Index: leahi_dialin/dd/modules/piston_pump.py
===================================================================
diff -u -rec8a2600b9e8cf6fe7e02c200a1c24221ca86863 -rf0f1a6557cb07e31eb26bb8f8c70e87902f30626
--- leahi_dialin/dd/modules/piston_pump.py	(.../piston_pump.py)	(revision ec8a2600b9e8cf6fe7e02c200a1c24221ca86863)
+++ leahi_dialin/dd/modules/piston_pump.py	(.../piston_pump.py)	(revision f0f1a6557cb07e31eb26bb8f8c70e87902f30626)
@@ -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,