GE RX3i User Manual page 168

Command 3004, Example 1 – Set Single Register
Write one register from %AI10 to register address 200 in the remote Modbus/TCP server. Return the COMMREQ
Status word to %R10. Use channel 6, a channel previously opened with the Open Modbus/TCP Client
Connection COMMREQ.
Dec
Word 1 00008 (0008)
Word 2 00000 (0000)
Word 3 00008 (0008)
Word 4 00009 (0009)
13
Word 5 00000 (0000)
Word 6 00000 (0000)
Word 7 03004 (0BBC)
Word 8 00006 (0006)
Word 9 00006 (0006)
Word 10 00010 (000A)
Word 11 00010 (000A)
Word 12 00200 (00C8)
Word 13 00001 (0001)
Word 14 00001 (0001)
(Word 7) Channel Command Number: Word 7 identifies the COMMREQ as a Write Data to remote
Modbus/TCP device.
(Word 8) Channel Number: Word 8 identifies the channel number previously allocated for communication with
the remote Modbus/TCP server.
(Word 9) Modbus Function Code: Word 9 specifies Function Code 6, Write Single Register.
(Word 10) Local PLC Memory Type: Words 10–11 specify the location in the local PLC from where the Ethernet
interface will get the data to be written to the remote PLC. Valid values for Word 10 are listed on page 150.
(Word 11) Local PLC Starting Address: Word 11 determines the starting address in the local PLC from which
the data is to be written. 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.
(Word 12) Remote Device Address: specifies the destination register in the remote device.
(Word 13) Number Registers in Remote Device: Word 13 specifies the quantity of registers to write to the
remote device. For Function Code 6, Write Single Register this must be set to 1.
(Word 14) Unit Identifier: This field is typically used by Ethernet to Serial bridges to specify the address of a
Modbus Slave on a multi-drop link. The Modbus/TCP Unit Identifier is a special control code used in a
Modbus/TCP message block.
GFK-2224Q
(Hex)
Length of Channel command Data Block
Always 0 (no-wait mode request)
Memory type of CRS word (%R)
CRS word address minus 1 (%R10)
Reserved
Reserved
Write to a Modbus/TCP Device
Channel number (6)
Modbus Function Code – Write Single Register
Local PLC Memory Type
Local PLC Starting Address
Address in the Remote Device
Number of Registers in the Remote Device
Unit Identifier
January 2017
Chapter 9. Modbus/TCP Client
155