Sporadic erroneous analog module readings possible with some M4RTU controllers

Applies To:

M4RTU

Versions Affected:

Problem was discovered in version: Rev. 2 Manufactured July 2007 to January 2008
Problem is corrected in controllers manufactured: February 2008 and after

Symptoms:

When two analog modules are placed adjacent to each other on an M4RTU I/O board, it is possible for a sporadic, erroneous value to occur and then to correct itself. The erroneous reading may occur on either module. The erroneous value may be up to 20% more than the expected value, and may occur on either an input or an output module.

How to identify Rev. 2 controllers
Controllers with the newer CPU have a white label with "Rev. 2." The label is adhered to the green printed circuit board below the top controller cover, between the digital and analog modules.

Workaround:

Moving analog modules apart, such as installing one in analog position 0 and one in position 2, but not one in position 1, eliminates the problem. Also removing an adjacent analog module prevents the problem from occuring.

Resolution:

Opto 22 had resolved this issue. If you are experiencing the above symptoms, contact Opto 22 Product Support for a repair authorization and an RMA number.

Questions?

Contact: Opto 22 Product Support.
Phone: 800-835-6786 or 951-695-3080
Email: support@opto22.com

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