S800 ci840 vs CI840a
We have one plant with S800 profibus slaves, this plant have been working for years, using combination CI840 / CI840A,
but last week some profibus slaves stopped working, reviewing we find that slaves with ci840 was not workin, and we replace with CI840A the profibus slaves work again,
we have 800XA V5.0 with CPUs PM861 and one ci854 .
Are the CI840 damaged or there is any problem with these modules and this version??
I was looking into ABB library but couldn't find any buelltins describing this kind of problem. There are some SW realted issues with CI840 card, where one of the modules stops in red. config. Bu then the are able to restart again.
The difference between CI840 and CI840A is improved and redisgned HW and CI840A was released around 2006.
It seems that there must have been some kind potential differences or lightning strikes casuing differences in the earth potential....
The CI840 and the CI840A are equal units and both are hot swappable...but, when a TU847 contains both a
CI840 and a CI840A, a pull-out of the CI840A will cause a controlled switch-over whereas a pull-out of a CI840 (if this
CI840 is master) may or may not cause a controlled switch-over. An uncontrolled switch-over causes a longer restore time
which may cause a temporary increase I/O update time. The CI840A is a hardware upgrade and is compatible with CI840.
The CI840 and CI840A can coexist; however, firmware in any redundant application of the CI840s must be the same. The
CI840A is a pin-compatible variant of CI840. The documentation is the same for the CI840A. To avoid the possible hick-up
of a CI840 when hot swapped, is to check if the CI840 is the master, and if it is, then first disconnect the profibus cable to
this board, wait for the other board (CI840A) to indicate that it became master, and then hot swap the CI840