Rockwell Automation 20-COMM-I Interbus Adapter - Manual (Page 77)

Using Explicit Messaging (PCP Communications) 6-15
PCP Read Subroutine (Explicit Messaging)
The PCP Read Subroutine is executed from the Main Program (Chapter
5) by turning on bit B3:47/0. Only one PCP Read or Write can be
performed at any one time. B3:47/0 will be turned off by the subroutine
when the reading is complete and signals that another read (or write)
cycle can take place.
Figure 6.3 LAD5 - PCP Read Subroutine
SLC Ladder Example - Peripheral Communications
Protocol (PCP)
N22:10 = PCP Command Word (Always set to "4" to cause a PCP Read: a "4" = bit 2 ON)
0000
B3:47
1
PCP Read
Routine
1-shot
MOV
Move
Source
4
4<
Dest
N22:10
4<
MOV
PCP
Command
Word
N22:11 = The Communication Reference (CR) to read from. There is a unique CR for each Station.
"2" = CR 2 = Station 1.0
"3" = CR 3 = Station 2.0
0001
B3:47
1
PCP Read
Routine
1-shot
MOV
Move
Source
N22:0
2<
Dest
N22:11
2<
MOV
PCP Read
Command Msg
CR
20COMM-UM007A-EN-P.book Page 15 Tuesday, January 22, 2002 10:52 AM