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KB80024
Sporadic erroneous analog module readings possible with some M4RTU controllers
Revision:  2.0
Published:  2/12/2008
Applies To
M4RTU
Versions
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.

Relevant Downloads
No relevant downloads have been specified.
Questions? Contact Opto 22 Product Support.
Phone: 800-835-6786 or 951-695-3080
Email: support@opto22.com

DISCLAIMER

This Opto 22 Knowledge Base ('OptoKB') article is intended to provide general technical information on a particular subject or subjects and is not an exhaustive treatment of such subjects. Accordingly, the information in this OptoKB article is not intended to constitute application, design, software, or other professional engineering advice or services. Opto 22 may modify the OptoKB articles at any time. Before making any decision or taking any action which might affect your equipment, you should consult a qualified professional.

OPTO 22 DOES NOT WARRANT THE COMPLETENESS, TIMELINESS, OR ACCURACY OF THE DATA CONTAINED IN THIS OPTOKB ARTICLE AND MAY MAKE CHANGES THERETO AT ANY TIME AT ITS SOLE DISCRETION WITHOUT NOTICE. FURTHER, ALL INFORMATION CONVEYED HEREBY IS PROVIDED TO USERS 'AS IS.' IN NO EVENT SHALL OPTO 22 BE LIABLE FOR ANY DAMAGES OF ANY KIND INCLUDING DIRECT, INDIRECT INCIDENTAL, CONSEQUENTIAL, LOSS PROFIT, OR DAMAGE, EVEN IF OPTO 22 HAS BEEN ADVISED ON THE POSSIBILITY OF SUCH DAMAGES.

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