Micromod MOD: 30ML and Modcell Maintenance for 2001N, 2002N, and 1800R - Manual (Page 131)

Analog Output Readback Error
Diagnostic
MOD 30ML and Modcell have
Analog Output Module Error
Problem Description:
Instrument display or status display in ViZapp or Application Builder Software show “Module Error” for
AOM and extended error report shows a Readback Error
Applies to:
MOD 30ML configured from front face or Application Builder software or Visual Application Designer
ViZapp Software. It also applies to the Modcell Multiloop Processor.
Explanation:
This diagnostic can be triggered by a number of different problems, some of which are external to the
module. To determine if the error is due to a module failure, the extended error information must be read.
The extended error report can be read from the Status Page with the command R AOMn,EXTERR,
replacing "n" with the occurrence number of the module. Extended error information must be read after
receiving the module error, and before it has been acknowledged. Reading this information under any
other conditions will return a meaningless report.
Solution:
If the extended error report shows a Readback Error, the output circuit should be tested for noise
feedback from the field device. If the signal is clean, it may be a random occurrence, which can be
ignored.
We have conducted testing on modules manufactured over the last few years, and have found that a
percentage show occasional readback errors. The frequency of the error was random, but it always
cleared on the next scan (150mSec).
Topic: MOD 30ML/Modcell Technote: TNML1001-2
MicroMod Automation, Inc. Rev. 08-July-2003
AOM Readback.doc Page 1 of 2