Chapter 9. Modbus/TCP Client
GFK-2224Q
January 2017
143
9.2
COMMREQ Function Block and Command Block
This section describes the programming structures common to all Communications Requests: the COMMREQ
Function Block and the Command Block.
The COMMREQ Function Block
The Communications Request is triggered when the logic program passes power to the COMMREQ Function
Block.
(Enable ) -------------
(Command Block address)
(Rack/Slot Location of
the Ethernet Interface)
(Task value)
-
-
-
- Function Faulted (logic)
COMM
REQ
IN FT
SYSID
TASK
Figure 56: The COMMREQ Function Block
Each of the inputs and outputs are discussed in detail below. It is important to understand that the Command
Block address points to the location in memory you have setup as the Command Block.
Enable:
Control logic for activating the COMMREQ Function Block. See Section 5 for tips on developing your
program.
IN:
The location of the Command Block. It can be any valid address within a word-oriented area of memory
(%R, %AI, %AQ, %P, %L or %W for the Ethernet interface).
SYSID:
A hexadecimal word value that gives the rack (high byte) and slot (low byte) location of the Ethernet
interface. For the PACSystems embedded Ethernet interface, enter the rack/slot location of the module.
Examples:
Rack Slot Hex Word Value Notes
0
0
16#0001
RXi and CPE400
0
1
16#0001
Slot 1 is used for the Ethernet daughterboard on an RX7i CPU.
0
4
16#0004
3
4
16#0304
2
10
16#020A
4
2
16#0402
TASK:
For the RX3i and Rx7i ETM001 Ethernet interfaces TASK must always be set to zero. For PACSystems CPU
embedded Ethernet interface, TASK must be set to 65536 (0x10000) to address the CPU’s Ethernet
daughterboard.
Caution
Caution notices are used where equipment might be damaged if care is
not taken.
Summary of Contents for PACSystems RX7i
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