Rockwell Automation 1785-Lxxx Enhanced and Ethernet PLC-5 Programmable Controllers - Manual (Page 265)

Publication 1785-UM012D-EN-P - July 2005
Using Processor Input Interrupts 18-3
As shown in the following figure, the PII program must:
• count 100 tablets per group
• set an output at the 100th tablet
• reset the counter for the next group
The output image bit remains set until the next count.
Block-Transfers in Processor Input Interrupts (PIIs)
If the controller runs a PII that contains block-transfer instructions, the
controller performs these block-transfers immediately on completing any
block-transfers currently in the active buffer, ahead of block-transfer requests
waiting in the queue.
You can program “immediate” block-transfers to a local I/O chassis using the
PII program (i.e., the PII is invoked and the block-transfer occurs
immediately). The controller executes the block-transfer immediately,
completes the remaining rungs in the PII, then resumes execution of the
ladder program.
You can use the PII for a block-transfer to remote I/O. Remote
block-transfer instructions in a PII cause the controller to resume executing
user programs, while waiting for the block-transfer to complete. If you want
the PII to run to completion before returning to your main logic program,
include a UID and UIE instruction pair in your PII program file. Place the
block-transfer instruction inside of a UID/UIE pair.
CU COUNT UP
Counter
Preset
Accum
C4:0
100 DN
C4:0
DN
Output
CTU
RES
Output
C4:0
U
C4:0.CU
CLR
CLEAR
Destination S:51