1794-ASB local fault

[OkiePC 14]

I have a rack of flex I/O that had a bad module cauising an intermittent local fault on the 1794-ASB module. The rack is used for the main control panel I/O for the machine. The machine was in auto when the fault became persistent, and the operator was unable to stop the machine as it ran out of stock and made a small mess. The E-stop is hardwaired and was finally hit to shut it down. The flex i/o module 1794-IB16 which caused the fault has been replaced, but before I did that, I inserted contacts in the PLC code to shut down the machine in the case of a RIO fault on that rack. Well, when there is a local fault on the ASB, the rack fault bit remains cleared, so, as far as I can tell, the PLC cannot detect when this occurs. Does anyone have a workaround for this? I don't like the idea of losing communication with any I/O and not being able to program an orderly shutdown. Thanks Paul C.

[Ken Roach 194]

I answered this on another Forum, but it makes sense to follow up. The 1794-ASB has a feature called "Rack Fault Select" (RFS). This allows you to configure the adapter via a DIP switch setting to declare a Local Fault only if a module is removed, or to declare a Rack Fault that the Remote I/O scanner can detect. This feature is described on Page 2-9 of the current 1794-ASB Series E manual. Other FLEX adapters allow you to detect the slot status of each module individually, but Universal Remote I/O does not.