Modbus Protocol

iknowsomeplc · Jan 6, 2004

I never worked with Modbus protocol and now plans to learn it in an effort to update my automation knowledge. I have some modbus PLCs here to play with also. Anybody knows any site where modbus is explained in details so that I can write my own modbus driver?

Mickey · Jan 6, 2004

http://www.modbus.org/default.htm

Mickey

akreel · Jan 7, 2004

The hardest part is understanding how to generate the CRC code.
There are sample programs out there. I found one in the "ecomm manual" from Eurotherm (http://www.eurotherm.com/). They have a VERY detailed manual for their modbus products. Look for the downloads on their communicating thermostats.

AK

kalle · Jan 7, 2004

akreel said:
The hardest part is understanding how to generate the CRC code.

Or to notice that the transmission order of the High and Low byte of the CRC is opposite of the other Word's........

ayman metwally · Jan 8, 2004

and if you are interested in this stuff with visual basic , then try this :
http://www.dancon.com/techsup/visualbasic_modbus_example.htm

Modbus Protocol

iknowsomeplc

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akreel

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kalle

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ayman metwally

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