Wireless Profibus DP


Thread Starter

Julio Paredes


I have to connect to a facility separated from our main plant 7km aprox. We're still studying if it's better to connect two PLCs or a master PLC in plant with a remote ET200M (I prefer this one).

I've seen questions about wireless profibus before but I want to know if someone have tried one solution to do this before, because I've read that wireless profibus is not a good option and there's still no good technology to do this.

The connection speed we use is 187.5kbps.
Any help will be useful.



Koblenz, Mykel MH

Would wireless ethernet be a better option? I don't know your situation so I am not going to suggest that it is, just pose the question.

Ethernet has been tried and proven and may be a better solution for wireless connectivity, especially if what you say is true


Donald Pittendrigh

Token passing bus systems are a problem with half duplex radios. The Profibus must be slowed down to self defeating speeds to achieve acceptable target rotation times for the bus monitoring system. There are radios around that can do the job but they are horrifically expensive.

Use Ethernet communications with an 802.11G capable (NLOS) radio and you should be a happy chappy. Dlink makes a great industrial standard outdoor radio for aroung USD400

Donald Pittendrigh
If you use PROFIbus-DP and there are no remote backup master stations, there is no token passing. PROFIbus-DP uses only master/slave communications protocol, not token passing, to transfer data. Token passing is used only to
transfer bus mastership, usually to a backup master.

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Donald Pittendrigh

Apparently so, please explain the target rotation time concept which is applied to the monitoring of remote IO stations with a single master.

Donald, I can only assume that they are talking about the round-trip elapsed time between the Master's poll of the remote I/O station, and the completion of the data transfer requested by that poll. This is not token passing, although the Profibus specification still talks about "token rotation time" a similar phrase.

Dick Caro

Donald Pittendrigh

Precisely, and for that reason, let it be called token passing as everyone thinks they know what that means, and the end result amounts to the same thing.

Cheers Donald P