PICAXE communication via RS485 or MODBUS??

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paste

New Member
Dear friends, I have an assignment in college where I requested a PICAXE communicate via RS485 or MODBUS to another component. Is it possible to do this kind of communication?, What kind of communication has the PICAXE is RS232??.

Thank you very much for your help!
 
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tiscando

Senior Member
It may be possible for a PICAxe, using the serial commands, to communicate EIA/RS-485 through an RS-485 transciever like the MAX487 on Picaxe VSM/microprocessor/perhipherals, or, for a complete isolated EIA/RS-485 interface, the MAX1480 also on VSM, at least on the physical level. Most chips with the MODBUS protocol use the RS-485 physical interface. If you want to use the MODBUS data protocol, take a look at http://en.wikipedia.org/wiki/Modbus. As long as the baud rates are 2400, 4800 or 9600 +/- 10%, unless you are using HSERIN and HSEROUT on an X1 or X2 part where the baud can go almost any value up to possibly much more than 115200.
 
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graynomad

Senior Member
The Picaxe can communicate a few ways, you haven't spelled out exactly what you mean by "communicate". ie is it enough for one Picaxe to turn on a led when told to by the other, or do you need file transfer with error handling?

If by "Modbus" you mean using the Modbus protocol I think that would be way overkill for a college assignment. The protocol reference document is 121 pages long. They do have "Modbus over Serial" as well but that's still quite complicated.

Using RS485/232 would be easy though, just hook up a couple of transceivers and come up with your own simple protocol.

BTW, neither 485 nor 232 are a "protocol", they specify the hardware parameters of a serial link.
 
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