Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 67)

DH and DH+ Communication
Chapter 4
4-7
You specify the scanner that receives the command with an
extended address.
This address always takes the form:
E2.3. nn
Where: Function:
E2
specifies that this command addresses the moduleĆstatus area of
memory
3
specifies that you are sending the message instruction through the
scanner
nn
is replaced with the thumbwheel setting on your particular scanner
(1Ć15)
To enter a message instruction, do the following:
1. Enter a condition that, when true, activates the message instruction.
In Figure 4.2, we use an examine-on for input word 12, bit 01.
2. Enter MSG for the message instruction.
3. Choose a control file where status information about the message
command can be stored. The file should also be binary. In
Figure 4.2, we use binary file 200, word 0.
4. Enter an extended address for the channel. In Figure 4.2, we address
the module status area of memory, specify the scanner, and a
thumbwheel setting of 1.
5. Specify message type 1.
6. Enter either a command or a command procedure. Figure 4.2 uses
the command procedure PROC_A.
DH/DH+ Message Procedure
The scanner has its own programming language that consists of commands
(see chapter 6). A group of related commands make up a DH/DH+
message procedure. These commands and message procedures determine
what messages are transmitted over the DH or DH+ link.