Allen-Bradley PLC-5 - Block-Transfer Programming Considerations; General Considerations

Publication 1785-UM012D-EN-P - July 2005
Communicating with Remote I/O 6-19
For a list of block-transfer error codes, see the PLC-5 Programming Software
Instruction Set Reference, publication 1785-6.1.
Block-Transfer
Programming
Considerations
Read this section for information about general programming considerations
and considerations for controller-resident local racks.
General Considerations
The following are general programming considerations when you are
block-transferring I/O data.
C
Is the block-transfer for a
local I/O module?
yes
no
Block-transfer is for a module in a remote rack.
Sets the no response .NR bit (09).
Is the timeout .TO bit (08) set?
yes
no
Retries request once more before setting the .ER bit (12)
Re-initializes the request until
the watchdog timer expires (4 s).
Is the timeout .TO bit (08) set?
yes
no
Continues to request the block-transfer for 0-1 s
before setting the .ER bit (12).
Continues to request the
block-transfer until the watchdog
timer expires (4 s).