Index: leahi_dialin/dd/modules/piston_pump.py
===================================================================
diff -u -r9466b5c6b5867f392104a42608aa9542a7ff0358 -rdfbb4f080638b65d9836b22bd5c76d46d53abba5
--- leahi_dialin/dd/modules/piston_pump.py	(.../piston_pump.py)	(revision 9466b5c6b5867f392104a42608aa9542a7ff0358)
+++ leahi_dialin/dd/modules/piston_pump.py	(.../piston_pump.py)	(revision dfbb4f080638b65d9836b22bd5c76d46d53abba5)
@@ -151,7 +151,7 @@
         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,