CACM : MCM Communication Error

To avoid serious injury follow all warnings and instructions in the manual. Wear appropriate personal protective equipment.

CAN cables carry 24 V dc power and communicaton between modules.  A cross threaded CAN cable connector may cause problems with communication and/or power to modules.  Carefully check for cross threaded CAN connections on the MCM and on other modules.

  • Green light on each module should be lit.  If green light is not lit, check to make sure each CAN cable connection is not cross threaded and is tight.
  • Verify the power supply is outputting 24 V dc.  If not, check power supply wiring.  If wiring is okay, replace the power supply.

Insert a software upgrade token into the ADM and cycle the power.  Make certain to wait until the upload is complete before removing the token.  For more information on loading software, refer to the module programming manual by searching for "3A1244" at www.graco.com.

Check the CAN cables running between GCA modules.  Check for cross threading and tighten if needed.  If the problem still persists, grasp the cable near the connector, move it around, and watch the flashing yellow light on the GCA modules.  If the yellow light stops flashing, replace the CAN cable.

Ensure the MCM dial is set to the correct position.

  • E-30: dial position = 2
  • E-XP2: dial position = 3

Installing a new module in the system, or swapping in a module from another system, may cause a software mismatch.  Update software in all modules by following the procedure in your system's manual.  Make certain to wait until the upload is complete before removing the token.  For more information on loading software, also refer to the module programming manual by searching for "3A1244" at www.graco.com.