Serial I/O / Snp / Rtu Protocols - GE VersaMax PLC User Manual

12 Serial I/O / SNP / RTU Protocols

Serial I/O / SNP / RTU Protocols
For public disclosure
This chapter describes the VersaMax® CPU's Serial I/O feature, which can be used to
control the read/write activities of one of the CPU ports directly from the application
program.
This chapter also contains instructions for using COMMREQs to configure the CPU
serial ports for SNP, RTU, or Serial I/O protocol.
• Configuring Serial Ports Using the COMMREQ Function
• Configuring Serial Ports Using the COMMREQ Function
− RTU Slave/SNP Slave Operation with a Programmer Attached
− COMMREQ Command Block for Configuring SNP Protocol
− COMMREQ Data Block for Configuring RTU Protocol
− COMMREQ Data Block for Configuring Serial I/O
• Serial I/O COMMREQ Commands
− Initialize Port
− Set Up Input Buffer
− Flush Input Buffer
− Read Port Status
− Write Port Control
− Cancel Operation
− Autodial
− Write Bytes
− Read Bytes
− Read String
Details of RTU and SNP protocol are described in the Serial Communications User
Manual (GFK-0582).
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