Allen Bradley Block I/O


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We are working with an Allen Bradley PLC 5/60 with Remote I/O. The system currently has a 1/2 rack of I/O configured for rack 2 groups 0-3. Upon our DH trace we never saw such a thing. Yet the I/O Data file shows a "1" in the present bit for rack 2 group 0. If this is a half rack and it does exist shouldn't we have a 1 in each for both group 0 and group 2? We are only getting the single "1" back. Also none of the fault bits are present. I do believe that there is some misconfiguration here and it is preventing the BCM/BEM from switching to the secondary processor. Also, there are no errors on either the Block transfer Write or Block Transfer Read.
Thanks for your time.
Is there a -9 present in the .dlen of the BT word? If you afi the BT's for this rack does that 1 go away? Have you tried cutting the DH while the PLC is running and see if you then get some faults? I think that this should give you at least one fault. Don't worry about this affecting the process that is connected to the Remote I/O. AB remote I/O doesn't really need to be connected to the processor to control.
Did you try disconnecting the PLC from the network? Or cutting the DH? Make sure that the remote I/O is disconnected for at least 1 hr because it will reset the second processor in the PLC that does all the I/O scanning. The other option is to take apart the PLC and jumper the two jumpers together with a .22uF cap Jumpers 22 and 18. This prevents the I/O from scanning that Rack.
Each Module is a bi-directional right? Have you tried to transfer data to the rack's module buffers using CALL 6 or CALL 3. I believe they talk about this in page 133 in the manual of 17716534. My company has worked on many problems similar to this and the Matt guy was right. We found out that we couldn't send information to or from that rack and had to jumper two jumpers together per AB's request. The funny thing is no one even noticed this was a problem until my company took over the High tech water system. Well good luck and post any progress or anything you've tried.