CI854A in Redundancy Mode. frequent switching
I am having CI854A in Redundancy Mode. frequent switching (every once in 2 to 3 days) inCI854A is ocurring,while switching primary changes to secondary ,again secondary changes to primary within seconds and not stable. after some time it goes into stable mode and works normally. this module is related to DO.
following activites were done
1) RE-CRIMMPED THE CONNECTORS. 2) CHANGED THE CI854A TO NEW MODULE AND CHECKED. 3) CHANGED THE BACKPLANE OF CI854A.
still problem persists
Please check the below ALERT.
ALERT - PROFIBUS I/O on CI854A might Freeze Without Error Indication
PROFIBUS DP-V1 CI854AK01, 3BSE030220R1, (MTU + CI854A, 3BSE030221R1, PR:J)
PROFIBUS DP-V1 CI854AK01-eA, 3BSE030220R2, (MTU + CI854A-eA,
Units with revision PR:J, having Serial Number larger than SI1344xxxxx or have an
Inspection Date later than 20131120 might be affected by this problem.
A severe problem with the CI854A Communication Interface has been identified. The
problem can result in I/O from the affected PROFIBUS line stopping to update inputs or
outputs or both, without any error indication by the CI854A. Since the CI854A does not
detect or report the error no redundancy switch over to a redundant CI854A will happen.
When the problem occurs either all outputs are not updated anymore and keep the values
from before the error or all input values are not updated and also keep the values from
before the error. In some cases both all inputs and all outputs can be affected.
In the failure case for inputs the channel status of the I/O is not set into error state and for
outputs no OSP (Output Set as Predetermined) is activated. If however the CI854A is
removed or the controller is halted, all inputs/output will go to ISP/OSP.
In most cases when this error occurs, no error messages are seen in the controller
logs. However in some cases, a CI854A internal watchdog timeout has been observed
which is shown in the controller logs. In this case, the controller forces a CI854A restart to
occur thus recovering from the situation. Note that if CI854A are configured redundant, it
will failover to the backup CI854A. If the CI854A is configured as single, ISP/OSP value
will be set during the restart. See below (section “Controller log example of failing
CI854A”) for an example of a printout from controller log if the controller’s CEX bus
watchdog detects the issue.
The problem has only been observed in a subset of the units within the affected serial
number range. Of the total quantity of CI854A units within the scope for this field
communication less than 1% have reported the problem.
First try to decrease the BAUDRATE of CI854 in Settings folder - it could become stable especially if you have longer Profibus cables.
The settings of CI854 (Settings folder) are automatically calculated during download, but you can adjust them also and try again. For example from the manual:
The parameter TTR has to be increased manually when there is currently a great deal of disturbance or slaves are not present
Also you can try to modify Output Hold Time for CI840 - look in help for this module in CBM:
Value to set is 15 - 190. Time base is 10 ms, this result in 150 ms – 1,9 s. After a module fail over, a timer is started in the new Primary CI840. This CI840 requires configuration and data from PROFIBUS Master within Output Hold Time.