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GFK-1541B Chapter 4 Programming Modbus/TCP Channel Commands 4-5
4
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
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, or %AQ for the Series 90-30 Ethernet Interface).
SYSID:
A hexadecimal word value that gives the rack (high byte) and slot (low byte) location of
the Ethernet Interface. Note that if using GE Fanuc’s VersaPro PLC software, the leading zeros in
this hexadecimal word value are not displayed on-screen; for example, 0004 will appear as 4.
Examples:
Rack Slot
Hex Word Value
(LM90)
Hex Word Value
(VersaPro,
CIMPLICITY ME)
0 4 0004H 16#0004
34
0304H 16#0304
210
020AH 16#020A
4 2 0402H 16#0402