CAS MSC Troubleshooting - Remote Modbus

CAS MSC Troubleshooting - Remote Modbus

The following instructions detail how to troubleshoot the CAS MSC to make sure it is providing DC Voltage output to the motor.

Info
Checking Power to the Fan and MSC.

1. Make sure there is proper voltage to the fan and make sure the fan disconnect is in the ON position.
2. Check the MSC display to make sure it is illuminated and displaying information.
  1. If the MSC display is not illuminated, make sure there is a CAT-5 cable connected to the back of the MSC.
  2. Follow the CAT-5 and make sure it is routed to the ECPM03 Board (J3 or J5) in the space.
    1. If more than one MSC are on a job site, they may be daisy chained together.
3. If there is no display and the CAT-5 cable(s) is connected properly, there may be an issue with the CAT-5 or the MSC.
  1. The MSC can be moved to a fan with a known working MSC for testing.
    1. If the display illuminates when installed in a different fan, the CAT-5 cable needs to be replaced.
  2. The MSC can also be moved to the ECP and connected to J3 or J5 with a short CAT-5 for testing.
    1. If the display illuminates when connected directly to the ECP, there is likely an issue with the CAT-5 cable.
  3. If the display does not illuminated using either of the testing methods above, replace the MSC.
4. The MSC also requires a jumper installed across 0-10V IN and 0-10V OUT when set up for REMOTE MODBUS control.
  1. If no jumper is installed, you will need to install one.
  2. The MSC will not run the motor if the jumper is not installed.


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Checking the CAS MSC Configuration Settings

1. Once power is confirmed, press the MENU button to access the configuration menu. You should see BOARD CONFIG (1).
  1. Press ENTER and you will be prompted to enter the password (2). Using the UP and ENTER buttons, enter 0225 as the password (3).

2. Once the password is correct, press ENTER. You will want to make sure the MSC settings are correct before proceeding.
  1. MOTOR TYPE (4), CONTROL TYPE (5), and MODBUS # (6) are the main settings to confirm.

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Speed Adjustment

When the CAS MSC is set up for REMOTE MODBUS control, speed adjustment is done at the electrical control package (ECP) HMI.
The MSC(s) are assigned as VFD's in the ECP programming.
There may be low and high frequency settings or only high frequency settings, depending on how the ECP was ordered.
  1. If the ECP is set up for Dynamic operation, the system will have low and high frequency settings for exhaust and only high frequency for supply.
    1. Dynamic operation means that the fans will modulate between low and high frequencies based on temperature.
  2. If the ECP is set up for Static operation, the system will only have high frequency for both exhaust and supply.
    1. Static operation means that the fans will operate at one speed and they do not modulate.



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Troubleshooting

Once settings are confirmed, proceed with the troubleshooting information below.
  1. These steps are for CONTROL TYPE = REMOTE MODBUS.
1. Change CONTROL TYPE to LOCAL for testing. This will be set back to REMOTE MODBUS once testing is complete.
  1. If you do not set the MSC for LOCAL control, you will have to adjust the speed % at the ECP HMI. See the Speed Adjustment section above.
2. Unplug the black 4-pin connector from the back of the MSC. Change the SET SPEED % to 50%. Using a multi-meter set to DC Volts, check across the 2 pins where the red and yellow wires would plug into the MSC. At 50%, the DC Volts reading should be around 12 VDC.
3. If the output at 50% is correct, change the SET SPEED % to 100% and again, check DC Volts across the pins where the red and yellow wires would plug into the MSC. At 100%, the DC Volts should be around 24 VDC.
4. If both readings are correct, the issue is likely internal of the motor. If the voltage readings DO NOT correlate with the speed % settings, the issue is likely with the MSC.


Notes
MSC shown with wiring disconnected.