Allen Bradley SERCOS drives work differently than the Bosch drives. On site at a customer we discovered that the drives apparently will generate faults internally that they want to be cleared, but they don't report them in the SERCOS interface or even in the Drive Explorer software. This has been learned by exerience by the customer who has these drives.

A recent change to Clearing drive errors for SERCOS seems to have opened up an issue. When in Phase 4, a request to clear drive errors now will initiate a new phase progression from Phase 0. In Phase 2, each drive is checked for an error and it will get cleared if it is reporting one. The old software would clears errors, present or not.

In this new change we will be setting an override flag that tells Phase 2 to clear errors in every drive,even if the drive is not reporting one. This is a change that is being made on site. There is a possibility that the AB drive may not do the same processing in Phase 2 as it does in Phase 4. Implementing this in Phase 4 is not something I want to undertake on site, where I can't test it before hand. It is much more complicated.