Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 88)

Addressing DH and DH+ Data Transfers
Chapter 5
5-14
Important: The scanner ignores the message priority modifier for DH+
messages.
Command Message Type
Command messages can be protected or unprotected:
Protected commands can access only specified areas of data table
memory at a PLC-2 station. You need to send a protected write
command only if a switch at the remote PLC-2 station prohibits other
stations from sending unprotected write commands.
Unprotected commands can access any area of the data table.
For more information, see chapter 4.
By default, the assignment command generates protected command
messages. To generate an unprotected command message, enter a space
followed by a U after the assignment command statement.
For example:
#H027$0121 = 17407
The scanner generates a protected write command to write the value
17407 to word 121 of DH station 27.
#H027$0121 = 17407 U
The scanner generates an unprotected write command to write the
value 17407 into word 121 of DH station 27.
You can disable the transmission of unprotected commands through LIST
options (see chapter 2).
Identifying Remote Stations
Remote stations in an assignment command can be identified with an
integer value (Figure 5.10), a symbol, a PLC-3 data table address, or
system symbol.
For example:
#H(STANUM)$N0:0 = $N0:0 ; STANUM = 19
#H($N1:0)$N0:0 = $N0:0 ; $N1:0 = 19
#H(@SMITH)$N0:0 = $N0:0 ; @SMITH is equated to $N1:0