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Aubrey Kagan
04/05/12 13:13
Read: 786 times

#187016 - Modbus
Responding to: Murray R. Van Luyn's previous message
Modubus seems to answer most of your requirements. See

Being a master/slave working in 1/2 duplex, you can of course save a pair of wires.

Murray R. Van Luyn said:
The master may also need to ask certain slaves to operate outputs under their control, and have them report back when successfully done.

I don't know how you can do this in a master/slave operation, other than the master interrogating the status. How would the slave initiate a response?

Murray R. Van Luyn said:
Each of the slaves may end up with it's own serialised 16-bit node address, and the master will have to learn about the slave population through an initialisation-time address scanning procedure.

Typically the Modbus modules that I have used power up at a default address and the Modbus master can then configure it to a new address.

Murray R. Van Luyn said:
Disaster, they're making me code for PICs!!!

I sympathise. However, if I remember correctly, there is quite a bit of sample code for Modbus on the PIC.


List of 5 messages in thread
Data Link Layer for RS485?      Murray R. Van Luyn      04/05/12 11:37      
   Modbus      Aubrey Kagan      04/05/12 13:13      
      Yep, Modbus Fits The Bill.      Murray R. Van Luyn      04/05/12 14:49      
         Changing the Modbus Address      Aubrey Kagan      04/05/12 17:05      
            You've been busy.      Murray R. Van Luyn      04/06/12 12:04      

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