RS-485 vs Fieldbuses
RS-485 vs Fieldbuses
(OP)
Can PLC communicate only with RS-485? What i mean is does PLC's only communicate by fieldbuses, which are higher level protocols than RS-485, or if they can communicate with only RS-485? If both are possible what are the differences between the two? You can probably send less complicated data with RS-485 than with fieldbuses... And if a Siemens and an OMRON PLC communicate with RS-485 can they understand each other? Also, how is the data acquisition done by a software if it receives an RS-485 communication.
Thanx
Philippe St-Pierre
Thanx
Philippe St-Pierre





RE: RS-485 vs Fieldbuses
PLCs can communicate via RS-232, RS-485, and other communication links, using Ethernet, Controlnet, Devicenet, Foundation Fieldbus, Profibus, Modbus, etc., etc. Just about whatever you want.
The basic communication is ASCII over RS-232. It works, but is slow and very limited. A lot of vendors are headed toward Ethernet, running at 100MB/sec, built in HTML, and easy to interface.
RE: RS-485 vs Fieldbuses
Fieldbus's the advantage is that the governing associations have imposed some discipline as far as how the devices communicate and how date is sent. Usually there is a specification as far as the physical medium and there is a specification on the software. When you get to this level, if both devices claim they can use a particular fieldbus, chances are very good you'll be able to get the devices to communicate.
Good Luck