Shutting down Beckhoff PLCs (Mount/Coudé) for maintenance

Owned by Karl Newman
Last updated: Jul 12, 2023 by Karl Newman
2 min read

The Beckhoff C6920-0030 IPCs (Industrial PCs) for both Mount and Coudé are provided with screens and touchpads mounted on MCC1 and CCC1 enclosure doors. The IPC chassis and I/O terminals are enclosed within self-contained, removable MMCU (Mount Motion Control Unit) and CMCU (Coudé Motion Control Unit) modules. The front panel of each module has modular connectors providing interconnection to the field devices via terminal blocks. The front panel connectors -35109PL1 (Mount) and 77609PL1 (Coudé) route 24VDC and 0VDC to the PLC and Bus Couplers. The IPCs also incorporate built-in UPS hardware and external batteries. These batteries temporarily provide power to the IPCs and allows users to save any necessary files, etc. before shutting down. The UPS is the reason the main power breakers to the modules are not useful for dropping power to IPCs. In fact, turning the breakers off before shutting IPC down can prevent shutdown by triggering a restart via the PC_ON terminal [2].

The IPCs are Windows XP (x32 bit) devices that require a graceful shutdown to avoid (rare) OS corruption and maintain stable operation. The following steps are recommended:

  1. Using screen and touchpad double-click and run “Shutdown.bat” file via icon on the desktop.

  2. Wait till IPC shuts down and all LEDs on IPC and Bus Coupler terminals turn off.

  3. Turn off the circuit breakers -25010CB (Mount) or -69810CB (Coudé). These cut off the 24VDC to the MMCU and CMCU modules, respectively.

  4. Finally, pull the front panel power connector (-35109PL1 - Mount or 77609PL1 - Coudé). Removing connector ensures that the ground connection is severed from the outside preventing restart via PC_ON pin. The LED on the front panel should turn off after this step.

  5. To restore power run the above sequence in reverse.

 

References:

[1] ATST schematics (https://www.dropbox.com/s/oui3y1a76a5hkhe/ATST-30600_Circuit-Drawings_September%202021.pdf?dl=0).

[2] Beckhoff C6920 (https://www.dropbox.com/s/81si1zniwyqwxh9/C6920en.pdf?dl=0)