GE RX3i User Manual page 165

Chapter 9. Modbus/TCP Client
Command 3003, Example 3 – Read Exception Status
Read the Exception Status from the remote Modbus/TCP server. Store the Exception Data at location %Q4 (bit
mode). Return the COMMREQ Status word to %R10.
Dec (Hex)
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 03003 (0BBB)
Word 8 00006 (0006)
Word 9 00007 (0007)
Word 10 00072 (0048)
Word 11 00004 (0004)
Word 12 00000 (0000)
Word 13 00001 (0001)
Word 14 00001 (0001)
(Word 7) Channel Command Number: Word 7 identifies the COMMREQ as a Read Exception Status from the
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 Modbus Function Code 7, Read Exception Status.
(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 on page
150.(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. Be sure
this area is large enough to contain the requested data without overwriting other application data.
(Word 12) Reserved: Word 12 is reserved and must be set to zero.
(Word 13) Data Size: Word 13 is the data size and 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.
152 PACSystems* RX7i & RX3i TCP/IP Ethernet Communications User Manual
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
Read from a Modbus/TCP Device
Channel number (6)
Modbus Function Code (Read Exception Status)
Local PLC Memory Type
Local PLC Starting Address
Reserved
Data Size
Unit Identifier
GFK-2224Q