GE PACSystems RX7i Reference Manual

Also see for PACSystems RSTi-EP: User manual CPU Programmer's Reference Manual

Contents

GE PACSystems RX7i Reference Manual Manual pdf 7 page image

Contentsiv PACSystems* RX7i, RX3i and RSTi-EP CPU Reference Manual GFK-2222ADChapter 6 Serial I/O, SNP & RTU Protocols ...............................................................................2016.1 Configuring Serial Ports Using COMMREQ Function 65520 .......................................2026.1.1 COMMREQ Function Example .................................................................................................................................... 2026.1.2 Timing .................................................................................................................................................................................... 2026.1.3 Sending Another COMMREQ to the Same Port ................................................................................................. 2026.1.4 Invalid Port Configuration Combinations ............................................................................................................. 2036.1.5 COMMREQ Command Block Parameter Values ................................................................................................ 2046.1.6 Example COMMREQ Command Blocks for Serial Port Setup function ................................................... 2056.2 Serial I/O Protocol.............................................................................................................2086.2.1 Calling Serial I/O COMMREQs from the CPU Sweep ........................................................................................ 2086.2.2 Compatibility ...................................................................................................................................................................... 2086.2.3 Status Word for Serial I/O COMMREQs ................................................................................................................. 2086.2.4 Serial I/O COMMREQ Commands ............................................................................................................................. 2106.2.5 Overlapping COMMREQs .............................................................................................................................................. 2116.2.6 Initialize Port Function (4300) .................................................................................................................................... 2126.2.7 Set Up Input Buffer Function (4301) ....................................................................................................................... 2136.2.8 Flush Input Buffer Function (4302) .......................................................................................................................... 2146.2.9 Read Port Status Function (4303) ............................................................................................................................ 2156.2.10 Write Port Control Function (4304) ......................................................................................................................... 2176.2.11 Cancel COMMREQ Function (4399) ......................................................................................................................... 2186.2.12 Autodial Function (4400) .............................................................................................................................................. 2196.2.13 Write Bytes Function (4401) ....................................................................................................................................... 2216.2.14 Read Bytes Function (4402) ........................................................................................................................................ 2226.2.15 Read String Function (4403) ....................................................................................................................................... 2246.3 RTU Slave Protocol ...........................................................................................................2266.3.1 Message Format ............................................................................................................................................................... 2276.3.2 Cyclic Redundancy Check (CRC) ................................................................................................................................ 2326.3.3 RTU Message Descriptions .......................................................................................................................................... 2366.3.4 RTU Scratch Pad ............................................................................................................................................................... 2526.3.5 Communication Errors .................................................................................................................................................. 2536.3.6 RTU Slave/SNP Slave Operation with Programmer Attached ..................................................................... 2566.4 SNP Slave Protocol ...........................................................................................................2576.4.1 Permanent Datagrams .................................................................................................................................................. 2576.4.2 Communication Requests (COMMREQs) for SNP ............................................................................................. 257Appendix A Performance Data ...........................................................................................................259A-1 Boolean Execution Times .............................................................................................................260A-1.1 Boolean Execution Measurements (ms per 1000 Boolean executions) ................................................. 260A-2 Instruction Timing .........................................................................................................................261A-2.1 Overview .............................................................................................................................................................................. 261A-2.2 PLC Version Information ............................................................................................................................................... 262