RS 485 and the bus system

wolf691 · Dec 16, 2005

Hi everybody,
anyone can explain to me the relation of rs485 and the bus system like modbus, profibus and devicenet ?
thanks & regards !

BobB · Dec 16, 2005

RS485 is a transmission standard (2 wire). RS485 is 4 wire. Modbus is a protocol. There are several flavours of Modbus. The most popular is still Modbus RTU.

Have a look at www.modbus.com for information about the various Modbus protocols.

wolf691 · Dec 16, 2005

Thanks for the reply !

So can i say profibus and devicenet also transmit through the rs485 ??

BobB · Dec 16, 2005

So can i say profibus and devicenet also transmit through the rs485 ??

Not really. I do not know much about Profibus but use Device Net regularly.

Here is a link to a site where most/all industrial networks are listed and described. There are also some good links here about the respective networks.

http://ourworld.cs.com/rahulsebos/

Here is a link to the Device Net website

http://www.odva.org/

wolf691 · Dec 16, 2005

Thanks !!!!

danw · Dec 17, 2005

Yes, Profibus uses the RS-485 transmission standard.

Since Modbus is a protocol, it can run on RS-232 or RS-485 or even a current loop. When it runs over ethernet, it is called Modbus TCP.

Dan

elevmike · Dec 17, 2005

A quick analogy would be like this: RS-232,485 or whatever is the type of highway/road. Modbus is just a type of vheical used to transmit information on that road.

RS 485 and the bus system

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