comms network

[jimcav]

well heres the question, what type of network comms do you thinks is the most widely used on all plcs, excluding ethernet. my guess would be mod bus.

thanks
jim cav

 

[jstolaruk]

I guess it depends on what plcs you work around. the majority of my customers use AB so rs232 DF1, DH+, and DeviceNet are mostly what I see. Some ControlNET, Modbus+, and Profibus scattered here and there.

 

[Tark]

Proprietary comms

 

[Tom Jenkins]

It depends on what you mean by "most widely used". In terms of available on the most platforms, probably Modbus RTU in the USA. Outside the US Profibus may be more widely used.

In terms of number of nodes installed using a given protocol, in the US possibly one of the A-B protocols mentioned above may have more installed nodes than Modbus RTU, but I wouldn't bet on it. Outside the US I strongly suspect Profibus would win in this category.

 

[JesperMP]

Yes, outside the US Profibus is the most widely used standard.

"Ethernet" is not really ONE standard but a collection of various protocols. "Ethernet" would be a strong contender for the title "most used", but no single Ethernet protocol dominates, and they do NOT talk to each other !

edit: Oh, I see that jimcav said "excluding ethernet". Forget my ramblings.