Rockwell Automation 1747-ASB Remote I/O Adapter - Manual (Page 92)

Publication 1747-UM006B-EN-P - June 2003
6-6 Start-Up and Operation
Remote Expansion Chassis
Power Loss If power to any remote expansion chassis is lost, a 1747-ASB module
error occurs. When power to the remote expansion chassis is
restored, the 1747-ASB module acts as if its own chassis power was
cycled and resets itself, restoring normal operation unless a major fault
occurred.
The 1747-ASB module assigns each slot in the remote chassis and
remote expansion chassis a fixed amount of its image using slot
addressing. The 1747-ASB module then maps the I/O module's
images to the portion of the 1747-ASB image that is assigned to their
slots.
Invalid RIO Link Transfers If the I/O module in any slot is block transfer mapped, the 1747-ASB
module expects data for that I/O module to be transferred on the RIO
link using RIO block transfers. If the I/O module in any slot is
discretely mapped, the 1747-ASB expects data for that I/O module to
be transferred on the RIO link using RIO discrete transfers.
An Invalid RIO link transfer occurs when the 1747-ASB module
receives data for a slot in a manner other than that for which the
1747-ASB module is expecting to receive data for that slot.
Invalid RIO link transfers are categorized below. Errors are not
generated by these conditions:
•
RIO discrete or block transfers to empty or nonexistent slots
•
RIO discrete transfers to block transfer slots
•
RIO block transfers to discrete slots
•
invalid length RIO block transfers
RIO Discrete or Block Transfers To Empty or Nonexistent Chassis
Slots
Discrete output image data received by the 1747-ASB module or RIO
block transfers to empty or nonexistent slots are ignored by the
1747-ASB module.
Discrete input image data sent by the 1747-ASB module for empty or
nonexistent slots are all zeros.