Table 25. Binary outputs 1 and 2 troubleshooting of configuration and operation for 2-stage
Step Number
Action
Probable Cause
Step 1
Connect the Rover service tool to the LonTalk communication link, start the Rover service tool,
and select the MP501 you are troubleshooting from the Active Group Tree. The device plug-in
for the selected MP501 will appear with the Status screen displayed in the workspace.
See the
Rover Service Software Installation, Operation, and Programming
Guide
(EMTX-
SVX01).
—
Step 2
Select the Configuration button to display the Device Configuration screen. Select the PID tab
and verify the maximum output.
If the PID maximum is less than 30%, binary output 1 will not come on. If the PID maximum
is less than 70%, binary output 2 will not come on. See
Verify that the gains are not 0. If all three gains are 0, the PID output will always be 0 and both
outputs will be off.
PID loop configuration
problem.
Step 3
Select the Close button to display the Status workspace, then look on the Unit tab.
Is the MP501 in unoccupied mode if configured as SCC? If configured as generic the MP501 may
be disabled. If the mode is unoccupied (SCC) or disabled (generic), the controller commands
both outputs off.
If the controller is unoccupied but you think it should be in a different state, see
Arbitration (Only SCC Mode),” p. 52
The MP501 is in
unoccupied mode
(SCC) or disabled
mode (generic).
Step 4
At the Unit tab in the Status workspace, check diagnostics.
In SCC mode, if you’re not using the network space temperature input and the hardwired space
temperature input fails, binary outputs 1 and 2 go off.
Similarly, in generic mode, if you’re not using the network input and the hardwired input
(temperature, flow, pressure, percent, ppm) fails, binary outputs 1 and 2 go off. The controller
will return to normal operation when the sensor is no longer failed.
Sensor failure
diagnostic.
Step 5
Compare the input to the setpoint.
In SCC mode, the controller may be calculating that no heating or cooling capacity is required
at this time, so it is normal for binary outputs 1 and 2 to be off.
Similarly, in generic mode, the input may be close enough to the setpoint that binary outputs
1 and 2 remain off.
Capacity not required.
Step 6
Check to see if either of the network variables nviCmdOverride or nviEmergOverride is keeping
binary outputs 1 and 2 off. These variables can override the output.
To view nviCmdOverride and nviEmergOverride, refer to the
Rover Service Software
Installation, Operation, and Programming Guide
(EMTX-SVX01).
Override.
52
CNT-SVX08F-EN
Troubleshooting
Occupancy Arbitration (Only SCC Mode)
This section describes in detail how the MP501 determines its occupancy mode. Use
and
to verify why the MP501 is in its current mode.
The occupancy of the controller in SCC mode is determined by evaluating the combination of three
communicating inputs, the hardwired occupancy input, and the timed override on and cancel
buttons on the Trane zone sensor.
Three different communicating inputs affect the controller's occupancy mode:
•
Occupancy—manual command (nviOccManCmd)
•
Occupancy—schedule (nviOccSchedule)
•
Occupancy—sensor (nviOccSensor)
These outputs provide maximum flexibility, but the number of inputs used varies with the
application.
Occupancy; Manual Command
Some communicating devices may request occupancy based on the information communicated
in the network variable known as nvoOccManCmd. Trane systems and zone sensors do not
communicate this information to the controller, but the controller accepts this network variable as
a communicated input nviOccManCmd.
