COMM: Communication using CP341 as Modbus master with 4 slaves

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------------ Forwarded Message ------------
From: yan
To: AUTOMATION at CONTROL.COM
Subject: Re: COMM: Communication using CP341 as Modbus master with 4 slaves

I am working with the manual "CP 341 Point-to-Point Communication Installation and Parameter Assignment" but this doesn't explain how I configure communication with both a CP341 and a slave (GE F650). You said that the Physical
connections are crucial, and now I don't know if my cable is ok.

Now I have the message F1CO:0E54 AND F1CO:0E52.

If you have a good manula that explains the physical connections I will be very happy. Thanks!

My email is yan @ ihm. com. br


On May 21, 2008, dchartier wrote:
>Hello Ajith;
>
>I have done projects like yours and I
>can give these recommendations:
>In first stage, connect the master to
>only one slave at a time. Phisical
>connections on the cable are crucial,
>they must be checked slave by slave,
>also the slave must be configured
>properly, and you must check the DONE
>and NDR bits of the Send and RCV
>functions to make sure they acknowledge
>transmissions.
>
>Remember that if you are using a single
>cable to connect master and all slaves
>then they must all have the same
>interface parameters (speed, parity,
>stop bits...).
>
>Once all 4 slaves work individually and
>you are sure they are all compatible,
>you must build a calling function in
>the master that will synchronize the
>pairs of SEND/RCV functions for each
>slave; that is, wait for the NDR bit of
>the RCV function for slave no. 1 before
>calling the SEND function for slave
>no.2... Do it cyclically (slave no.4,
>slave no.1, slave no.2...) so the
>processor has confirmation of each
>transmission before going on to the
>next. This slows the exchanges a bit
>but they are then all reliable. <

( Complete thread: http://www.control.com/thread/1026244920 )