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Topic: Arduino serial to 20ma current loop (Read 414 times) previous topic - next topic

Mr Parp

Hi,

I need to interface to a serial interface on an industrial bus.  The interface has a 20ma current loop, logical 1 = 0mA in loop, logical 0 = 20ma.  It expects me to provide 6.5VDC.  It runs at 4800 baud.  To complicate things it has a parity bit, i.e. its 8o1.

( I know I can buy a dongle that will do say RS232 to 20ma current loop, but obviously I'd have to go RS232 first and checking my options. )

I presume I can connect one of the MEGA's hardware UARTs to it via appropriate circuitry and the parity can be handled with an serial register, e.g. UCSR1C=..

Regarding the circuit, will something like Midi circuit work?  I know they are current loop and I presume if I set things for the right current and voltage, I should be good to go.  I need RX an TX though.

Any advice from anyone whose already done this?

ta
chris

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