GE PACSystems RXi User Manual

Chapter 8. Gigabit Ethernet (GbE) Interface Overview and Operation176 PACSystems* RXi Distributed IO Controller User Manual GFK-2816FCommand 3004, Example 1 – Set Single RegisterWrite 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 openedwith the Open Modbus TCP Client Connection COMMREQ.Dec (Hex)Word 1 00008 (0008) Length of Channel command Data BlockWord 2 00000 (0000) Always 0 (no-wait mode request)Word 3 00008 (0008) Memory type of CRS word (%R)Word 4 00009 (0009) CRS word address minus 1 (%R10)6Word 5 00000 (0000) ReservedWord 6 00000 (0000) ReservedWord 7 03004 (0BBC) Write to a Modbus TCP DeviceWord 8 00006 (0006) Channel number (6)Word 9 00006 (0006) Modbus Function Code – Write Single RegisterWord 10 00010 (000A) Local Controller Memory TypeWord 11 00010 (000A) Local Controller Starting AddressWord 12 00200 (00C8) Address in the Remote DeviceWord 13 00001 (0001) Number of Registers in the Remote DeviceWord 14 00001 (0001) Unit Identifier(Word 7) Channel Command Number: Word 7 identifies the COMMREQ as a Write Data to remoteModbus TCP device.(Word 8) Channel Number: Word 8 identifies the channel number previously allocated forcommunication with the remote Modbus TCP server.(Word 9) Modbus Function Code: Word 9 specifies Function Code 6, Write Single Register.(Word 10) Local Controller Memory Type: Words 10–11 specify the location in the local controllerfrom where the Ethernet interface will get the data to be written to the remote controller. Validvalues for Word 10 are listed on page ICRXICTL000, GFK-2816, GFK2816171.(Word 11) Local Controller Starting Address: Word 11 determines the starting address in the localcontroller from which the data is to be written. The value entered is the offset (1-based) fromthe beginning of controller memory for the memory type and mode specified in Word 10. Thisoffset will be either in bits, bytes, or words depending on the mode specified. Valid ranges ofvalues depend on the controller’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 writeto 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 theaddress of a Modbus Slave on a multi-drop link. The Modbus TCP Unit Identifier is a specialcontrol code used in a Modbus TCP message block.