GE GFK-1541B User Manual
Page 128
GFK-1541B
Chapter 4 Programming Modbus/TCP Channel Commands
4-13
4
(Word 10) Local PLC Memory Type:
Words 10-11 specify the location in the local PLC where
the Ethernet Interface will store data received from the remote device Valid values for Word 10
are listed below.
Type
Value
(Decimal)
Description
%R
8
Register memory (word mode)
%AI
10
Analog input memory (word mode)
%AQ
12
Analog output memory (word mode)
%I
16
70
Discrete input memory (byte mode)
Discrete input memory (bit mode)
%Q
18
72
Discrete output memory (byte mode)
Discrete output memory (bit mode)
%T
20
74
Discrete temporary memory (byte mode)
Discrete temporary memory (bit mode)
%M
22
76
Discrete momentary internal memory (byte mode)
Discrete momentary internal memory (bit mode)
%SA
24
78
Discrete system memory group A (byte mode)
Discrete system memory group A (bit mode)
%SB
26
80
Discrete system memory group B (byte mode)
Discrete system memory group B (bit mode)
%SC
28
82
Discrete system memory group C (byte mode)
Discrete system memory group C (bit mode)
%S
30
84
Discrete system memory (byte mode)
Discrete system memory (bit mode)
%G
56
86
Discrete global data table (byte mode)
Discrete global data table (bit mode)
Read-only memory, cannot be written to.
(Word 11) Local PLC Memory Address:
Word 11 determines the starting address in the local
PLC in which the data from the remote device is to be stored. The value entered is the offset (1-
based) from the beginning of PLC memory for the memory type and mode specified in Word 10.
This offset will be either in bits, bytes, or words depending on the mode specified. Valid ranges
of values depend on the PLC’s memory ranges. The user is responsible for assuring that this area
is large enough to contain the requested data without overwriting other application data.
(Word 12) Remote Device Address:
Word 12 specifies the address in the remote Modbus/TCP
device. Note: The function code determines the Modbus address area 3xxxx or 4xxxx, Word 12 is
the address within this area (eg. you enter 200 not 30200 in this example).
(Word 13) Number Registers in Remote Device:
Words 13 specifies the quantity of registers
(16bit words) to read from the remote device.
(Word 14) Unit Identifier:
Word 14 is the Modbus/TCP Unit Identifier, a special control code
used in a Modbus/TCP message. The default is 1.This value is 1 for most Modbus/TCP devices
except if a Ethernet to Serial bridge is used to multidrop to Modbus RTU devices.