Rockwell Automation 1771-KA2 Communication Adapter Module - Manual (Page 112)

Start–up and Troubleshooting
Chapter 9
9-10
Optional test rungs are shown in Figure 9.5. Within this ZCL area, the
START bit is unconditionally LATCHED ON (rung 2) and UNLATCHED
when the DONE bit is ON (rung 3). In rung 1, a single input image table
bit is the condition for the ZCL area.
Figure 9.5
Optional Test Rungs
Rung ZCL
111 00
1
L
032 10
Start Bit
U
032 10
032 00
Done Bit Start Bit
ZCL
2
3
4
Rungs may
be left in
program for
subsequent
trouble-
shooting.
Input address for ”Force On” manipulation.
(Input address which is always turned OFF by
I/O scan.)
Rung
Rung
Rung
The input image table bit examined in rung 1 must always be turned OFF
by the processor I/O scan. This bit can be any unused input image table
bit. For this purpose, choose a bit that is not usable because its
corresponding I/O chassis slot contains an output module.
Because the processor turns this bit OFF on each I/O scan, the ZCL area
is disabled unless both of these conditions are met:
The programming terminal is connected to the processor, that is, to the
communication adapter module PROGRAM INTERFACE socket
The addressed input image table bit is FORCED ON
When both of these conditions are met, the commands programmed at a
station processor can be initiated and monitored. To test individual
commands, the addresses of the corresponding START and DONE bit are
entered into rungs 2 and 3. In this manner, each command can be tested
individually.