Index: leahi_dialin/dd/modules/piston_pump.py
===================================================================
diff -u -rf9dd375900151a5daafe3b687187187645d5f1ab -ra313166ac02fdc81a9d2b24eca45cded18fd468e
--- leahi_dialin/dd/modules/piston_pump.py	(.../piston_pump.py)	(revision f9dd375900151a5daafe3b687187187645d5f1ab)
+++ leahi_dialin/dd/modules/piston_pump.py	(.../piston_pump.py)	(revision a313166ac02fdc81a9d2b24eca45cded18fd468e)
@@ -5,7 +5,7 @@
 # THIS CODE MAY NOT BE COPIED OR REPRODUCED IN ANY FORM, IN PART OR IN
 # WHOLE, WITHOUT THE EXPLICIT PERMISSION OF THE COPYRIGHT OWNER.
 #
-# @file    piston_pumps.py
+# @file    piston_pump.py
 #
 # @author  (last)      Micahel Garthwaite
 # @date    (last)      07-Mar-2023
@@ -20,13 +20,20 @@
 from .constants import RESET, NO_RESET
 from leahi_dialin.common.msg_defs import MsgIds, MsgFieldPositions
 from leahi_dialin.protocols.CAN import DenaliMessage, DenaliChannels
-from leahi_dialin.utils.base import AbstractSubSystem, publish
+from leahi_dialin.utils.base import AbstractSubSystem, publish, DialinEnum
 from leahi_dialin.utils.checks import check_broadcast_interval_override_ms
 from leahi_dialin.utils.conversions import integer_to_bytearray, float_to_bytearray
 
+@unique
+class DDPistonPumpsEnum(DialinEnum):
+    ACID = 0                        # Acid piston pump
+    BICARB = 1                      # Bicarbonate piston pump
+    UF = 2                          # Ultrafilteration piston pump
+    NUM_OF_PISTON_PUMPS = 3         # Number of piston pumps
+
 class DDPistonPumps(AbstractSubSystem):
     """
-    PistonPumps
+    DDPistonPumps
 
     Dialysate Delivery (DD) Dialin API sub-class for piston pumps related commands.
     """
@@ -126,14 +133,14 @@
             self.logger.error("Timeout!!!!")
             return False
 
-    def cmd_piston_set_start_stop(self, pump_id: int, command: int, count: int, speed: float, volume: float ) -> int:
+    def cmd_piston_set_start_stop_override(self, pump_id: int, command: int, count: int, flow_rate: float, volume: float ) -> int:
         """
         Constructs and sends the piston pump start stop command
 
         @param pump_id: unsigned int - concentrate pump ID
         @param command:  int - value to command the concentrate pump
         @param count: int - vale to set the cycle count to
-        @param speed:  float - ml/min to set the speed to
+        @param flow_rate:  float - ml/min to set the speed to
         @param volume: float - the volume to set to
         @return: 1 if successful, zero otherwise
 
@@ -142,7 +149,7 @@
         pmp = integer_to_bytearray(pump_id)
         cmd = integer_to_bytearray(command)
         cyc = integer_to_bytearray(count)
-        spd = float_to_bytearray(speed)
+        spd = float_to_bytearray(flow_rate)
         vlm = float_to_bytearray(volume)
         payload = pmp + cmd + cyc + spd + vlm
 
@@ -161,4 +168,36 @@
             return received_message['message'][DenaliMessage.PAYLOAD_START_INDEX]
         else:
             self.logger.error("Timeout!!!!")
+            return False
+
+    def cmd_piston_pump_fill_after_dispense_override(self, fill: bool, reset: int = NO_RESET) -> int:
+        """
+        Constructs and sends the piston pump fill after dispense override command
+        Constraints:
+            Must be logged into DD.
+
+        @param fill:  integer - 0 = false, 1 = true to override piston pump fill
+        @param reset:  integer - 1 to reset a previous override, 0 to override
+        @return: 1 if successful, zero otherwise
+        """
+
+        reset_byte_array = integer_to_bytearray(reset)
+        fl = integer_to_bytearray(fill)
+        payload = reset_byte_array + fl
+
+        message = DenaliMessage.build_message(channel_id=DenaliChannels.dialin_to_dd_ch_id,
+                                              message_id=MsgIds.MSG_ID_DD_PISTON_PUMP_FILL_AFTER_DISPENSE_OVERRIDE_REQUEST.value,
+                                              payload=payload)
+
+        self.logger.debug("override DD piston pump fill after dispense.")
+
+        # Send message
+        received_message = self.can_interface.send(message)
+
+        # If there is content...
+        if received_message is not None:
+            # response payload is OK or not OK
+            return received_message['message'][DenaliMessage.PAYLOAD_START_INDEX]
+        else:
+            self.logger.error("Timeout!!!!")
             return False
\ No newline at end of file