Rockwell Automation 1747-ASB Remote I/O Adapter - Manual (Page 70)

Publication 1747-UM006B-EN-P - June 2003
4-16 Configuration
When hold last state is selected, outputs are held in their last state
when any of the following conditions occur:
•
RIO link communications is lost due to a broken cable or
scanner fault.
•
The 1747-ASB module is inhibited by the scanner.
•
The 1747-ASB module receives reset, adapter decide commands
from the scanner.
When the discrete outputs are being held in their last state, consider
the following:
•
The specialty modules operate as if they are being controlled by
an SLC processor that is in the test mode. See the specialty I/O
module's manual to determine the response to this condition.
•
The specialty I/O module's inputs are still read by the 1747-ASB
module. However, the specialty I/O module's outputs are not
modified by the 1747-ASB module.
Your system must be designed so it is in a safe state when all discrete
outputs are off, or cleared.
The 1747-ASB module is shipped from the factory with the hold last
state switch in the OFF position (do not hold last state).
ATTENTION
!
When hold last state is selected and specialty I/O
modules are being used, the operation of the
specialty I/O modules must be considered when the
discrete outputs are being held in their last state.