Rockwell Automation 1771-ASB/E Remote I/O Adapter User Manual - Manual (Page 81)

Appendix
D
Publication 1771ĆUM001A-US-P - February 2000
Questions and Answers
This appendix presents some of the most commonly asked questions
about application and operation of the Remote I/O Adapter Module.
The following questions and answers do not cover all possible
questions, but are representative of the more common ones.
Q. What happens to my inputs and outputs when an adapter
communication failure occurs?
A. On a communication failure, inputs in this rack will appear
in the processor input image table in the last state they were
reported to be in before the failure. Outputs in this rack will
either remain in their last state or be turned off, depending
on the I/O chassis backplane switch setting for output last
state.
Q. Is there a way to monitor my remote rack status and take
appropriate action if there is a rack fault or a communication
failure?
A. Yes. Processor rack fault bits can be monitored.
Communication failure can be detected by monitoring the
program’s block transfer error bit. A diagnostic step array
and timer can be programmed to monitor the status of
changing digital inputs. In all cases, the appropriate action
can be taken, i.e. program a fault routine.
Q. I just replaced my series B adapter with a series E adapter,
and now my block transfers are timing out (block transfer
error code –9). What’s wrong?
A. Certain scanner modules require series B emulation which
includes a delay to provide the scanner sufficient time to
service all of its communication ports. If you are using a
1772-SD2, 1775-S4, 1775-S4A, 1775-S5, 1775-SR5 or
1775-SR scanner, set the link response for unrestricted or
series B emulation (switch S2, position 5 on).
Questions and Answers