Rockwell Automation RECOMM-IBUS Interbus Communications Module - Manual (Page 71)

Using Explicit Messaging (PCP Communications) 7-11
The sample ladder logic program simplifies addressing the various
PCP indexes. Before calling the PCP Write Subroutine (figure 7.13),
six registers are loaded to identify the variable to write:
The PCP Write Subroutine uses the data in table 7.10 to create the
following Command Message:
Table 7.10 – PCP Write Main Program Data
Register Description
N23:0
The Communication Reference (CR) to write to:
Set to “2” to access Station 1.0 (CR=2)
Set to “3” to access Station 2.0 (CR=3)
N23:1 The desired parameter area to be accessed:
Set to “0” for DPI Host parameters
Set to “1” for RECOMM-IBUS parameters
N23:2 The actual parameter number to write to (1, 2, ....n).
N23:3 The number of bytes of data to write:
Set to either “1” (1 byte), “2” (2 bytes) and “4” (4
bytes)
N23:4 Data Word #1
(1 and 2-byte writes, MSW of 4 byte write).
N23:5 Data Word #2
(LSW of 4-byte write).
Table 7.11 – PCP Write Subroutine Command Message
Register Description
N23:10 The PCP Command word (set to “8” for PCP Write).
N23:11 The Command Reference (CR) to write to.
N23:12 The PCP Index of the variable to write (“306Ah” =
Host parameter 106, etc.).
N23:13 Sub Index not used.
N23:14 The number of bytes of data to write (set to “1”, “2”
or “4”).
N23:15 Data word 1.
N23:16 Data word 2.