Have a look at your Auxiliary storage lower limit (QSTGLOWLMT system value) vs your available disk <i>space. The AS/400 is disconnecting some communication features when the lower limit is exceeded.
The CPF5140 message is a sort of general message stating that your device is no longer communicating. You’ll need to look a bit further back in the joblog to see the real cause of your problem.
Try to find the first message that says there’s a problem with some sort of communications or that a program has crashed. I suspect that the program that runs on this machine is causing some sort of fatal error and ending your session.
Did you upgrade OS/400 or your application program or apply PTF’s around the time that your problem started?
Your statement <i>”We thought it was a networking problem and persueded that. There is a 2nd thin client used for AS/400 emulation and e-mail only. It has never been interrupted. Even after reversing the cables on the two the T&A client dropped and the E-Mail client did not”</i> really makes me think that the T&A client is the issue.
The T&A client probably has long periods of time when it is not communicating and other periods when it is accepting scans. When are you getting the CPF5140 errors?