THE SMART SOLUTION FOR ENERGY EFFICIENCY
MPC MultiProtoCol DDC Controls
November 19, 2018
18
Fan Operation – Digital output point G (DO4) is the fan
output and is connected to the "G" terminal on the
CXM, DXM or DXM2 control. If fan Mode is set to "Auto"
ECM, then the fan is energized only during a call for
heating or cooling. "Auto" mode is the default mode of
operation At 30% PID, the fan(G) energizes in Auto
mode.
Heating/Cooling Changeover – The Digital output
"O" (DO3) is the RV output and is connected to the
"O" terminal on the CXM, DXM or DXM2 board. "O" is
energized during call for cooling. The RV (O) energizes
at 40% PID in cooling only.
Compressor Operation – The Digital outputs Y1 (DO1)
and Y2 (DO2) are the outputs for compressors stage
1 and 2. Y1 is connected to Y terminal on the CXM/
DXM/DXM2 and if the heat pump is dual stage, Y2 is
connected to a second CXM Y input or Y2 on the
DXM/DXM2.
Y1 and Y2 are off when the zone temperature is between
the heating and cooling set points. As the zone
temperature rises above cooling set point or below
heating setpoint, Y1 is energized at 50% PID and Y2 is
energized at 75%.
There is also a load sharing mode which permits
swapping the primary status of Y1 with Y2 depending
on compressor run time. The low time compressor
becomes primary and the high time compressor assumes
secondary status.
Note: All 5 digital outputs have associated LEDs to
indicate operating status. If the digital output is on,
then the associated LED will be on.
Occupied/Unoccupied Changeover – When the
MPC is in the stand-alone mode of operation, the
MPC defaults to the occupied mode of operation.
Occupancy changeover may be provided through the
communications network.
Troubleshooting Tips – If the BMS is having trouble
communicating with the MPC, check the following items
before contacting technical support.
• Make sure the MPC wiring is correct. Make sure
all color codes match and that no wire strands are
shorting over to other terminals.
• Make sure the MPC and other network controllers
have power and are turned on. Make sure all
equipment have power and LEDs lit with no solid
error light. Some devices, especially communication
devices, receive power from a source other than
a power cable or adapter. Some panels can be
reinitialized by resetting the panel.
• Verify operation of all LEDs: RX, TX, Power, Run,
DOs and error.
• Make sure that all jumpers are set to default and that
there is nothing jumped on the format pin.
MPC Sequence of Operation
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