What protocol for sending alarm from PLC->PC through rs & intelligent radiomodem?
I have to build communication channel between 6 PLC and 1 PC Workstation. Medium are "intelligent" radio modems with RS232/485 ports.
I've initially thought about using Modbus as communication protocol but as far as I know with that protocol I can't initiate connection from RTU (PLC) side and inform master station (PC) about fire or security alarm. Instead of with Modbus I must frequently send requests from PC to each PLC and check replies. Am I right? I don't like such scenario.
On the other hand I'm obliged to communicate between PLC and I/O modules through DeviceNet.
I'm in trouble:
What PLC supports both DeviceNet and any other protocol, suitable for radio communication channel, which could initiate message roundtrip from both sides (RTU&PC)? What is such suitable protocol? What should be configuration of radio modem transmission to avoid conflicts in a case two RTU at exactly the same time try send alarm to PC (rather impossible with fire alarms but possible with power-down alarms)
Thanks in advance,
WWalker
[email protected]
I have to build communication channel between 6 PLC and 1 PC Workstation. Medium are "intelligent" radio modems with RS232/485 ports.
I've initially thought about using Modbus as communication protocol but as far as I know with that protocol I can't initiate connection from RTU (PLC) side and inform master station (PC) about fire or security alarm. Instead of with Modbus I must frequently send requests from PC to each PLC and check replies. Am I right? I don't like such scenario.
On the other hand I'm obliged to communicate between PLC and I/O modules through DeviceNet.
I'm in trouble:
What PLC supports both DeviceNet and any other protocol, suitable for radio communication channel, which could initiate message roundtrip from both sides (RTU&PC)? What is such suitable protocol? What should be configuration of radio modem transmission to avoid conflicts in a case two RTU at exactly the same time try send alarm to PC (rather impossible with fire alarms but possible with power-down alarms)
Thanks in advance,
WWalker
[email protected]