Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 69)

DH and DH+ Communication
Chapter 4
4-9
Figure 4.4
Two Ways to Use Message Commands
STAT
MSG
MESSAGE TYPE 1 STAT
10012
01
STAT
CTL = FB200:0000=200
CHANNEL: E2.3.1
$B45:21=$112:33
EN
12
DN
15
ER
13
STAT
MSG
MESSAGE TYPE 1 STAT
10012
01
STAT
CTL = BW200:0000=200
CHANNEL: E2.3.1
@ PROC_A
EN
12
DN
15
ER
13
1) as a single command
in a PLC-3 message instruction 2) as part of a message procedure
Message Procedure PROC_A
(other commands)
$B45:21 = $112:33
(other commands)
PLC-3 Message Instruction to Control
Execution of Procedure PROC_A
15415
Access Privileges
Not every station can read or write to every other station. In general, read
and write access privileges depend on two factors:
type of processor at the transmitting and receiving stations
protections set at the receiving station
The rest of this section explains how these access privileges vary according
to the above factors.
PLC-3 Stations
PLC-3 stations can read and write to other PLC-3 station data tables. A
local PLC-3 station can prevent remote PLC-3 stations from writing to the
local station’s data table by setting the memory protect keyswitch.
To allow writes to local memory depending on the memory protect
keyswitch setting, select
Accept Writes in the DH/DH+ options menu in
LIST at the local station.