GE PACSystems RXi User Manual

Chapter 8. Gigabit Ethernet (GbE) Interface Overview and OperationGFK-2816F August 2015 173Command 3003, Example 3 – Read Exception StatusRead the Exception Status from the remote Modbus TCP server. Store the Exception Data atlocation %Q4(bit mode). Return the COMMREQ Status word to %R10.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 03003 (0BBB) Read from a Modbus TCP DeviceWord 8 00006 (0006) Channel number (6)Word 9 00007 (0007) Modbus Function Code (Read Exception Status)Word 10 00072 (0048) Local Controller Memory TypeWord 11 00004 (0004) Local Controller Starting AddressWord 12 00000 (0000) ReservedWord 13 00001 (0001) Data SizeWord 14 00001 (0001) Unit Identifier(Word 7) Channel Command Number: Word 7 identifies the COMMREQ as a Read ExceptionStatus from the Modbus 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 Modbus Function Code 7, Read ExceptionStatus.(Word 10) Local Controller Memory Type: Words 10-11 specify the location in the local controllerwhere the Ethernet interface will store data received from the remote device. Valid values forWord 10 are listed on page 171.(Word 11) Local Controller Memory Address: Word 11 determines the starting address in the localcontroller in which the data from the remote device is to be stored. The value entered is theoffset (1-based) from the beginning of controller memory for the memory type and modespecified in Word 10. This offset will be either in bits, bytes, or words depending on the modespecified. Valid ranges of values depend on the controller’s memory ranges. Be sure thisarea 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 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.