Applies To:
  • CitectSCADA 5.xx

We are seeing hardware errors on Momentum PLC's. If we go off the graphic page for > 10 seconds and then go back to the said page the kernel will display an error like the following:

"Wed Feb 27 17:45:57 2002 01:33:21.059 Error: Channel offline, cannot talk
READ 0015 PORT1_BOARD1 MomLab 000017 16
Generic 000021 Driver 00000020 (0x00000014)

Citect then re-establishes communications but if I go off the page then the same happens again.


The Momentum PLC closes socket connections after a period of no use that is greater than 10 seconds. This is a designed feature to maximise the use of the small number of sockets available for communications within the momentum.

However in an application a simple workaround should help; such as putting in a single alarm or trend tag that is read every 4 seconds or so, regardless of the opened page.