RESET of a CMX during disturbance of the redundancy unit
- Resetting the passive unit
The problem can be eliminated by conducting a new RESET of the passive unit, as then correct ‘Disturbed‘ and ‘OK‘ messages are generated by the RUPI.
The ‘Disturbed’ entry for the redundant unit in the L-bus or the SA-bus subscriber list is not deleted in the active CMX module after the disturbance has been eliminated.
The time between inserting the fuse into the active and into the passive CMX is greater than approx. 1 minute, as the disturbance is not recognized by the active unit until then.
The units appear outwardly normal (active CMX with continous light of thr green LED, LEDs of the passive CMX are dark). The passive unit is entered as disturbed in the L/SA-bus subscriber list of the active CMX module.
- The failure of the passive unit is not reported by the RUPI
The recognition of the failure takes place in the CMX module through the expiration of a monitoring time of approx. 1 minute, however the failure is only recognized on the A-bus and entered in the subscriber list. In order that the passive unit is fully (i.e. on both buses) linked in the case of a total failure and replacement, the ‘disturbed’ code is copied from the A-bus subscriber list into the L/SA-bus subscriber list by the controller of the automatic linking feature.
As the resulting linking commands are only evaluated by new or initialized units, no later entry in the subscriber lists takes place in the case of a temporary disturbance without a loss of the subscriber number, which would have led to the disturbance code being overwritten.
An ‘OK’ message by the RUPI is also not output due to the unrecognized disturbance. At the A-bus the unit is set to ‘OK’ again after reception of the redundancy status messages, however the ‘Disturbed’ entry in the L/SA-bus subscriber list is retained.
As a result, automatic linking commands are generated cyclically (approx. once per minute), which however, are not evaluated, i. e. there are no follow-up telegrams in the form of linking acknowledgements.