Arduino serial to 20ma current loop

Using Arduino Networking, Protocols, and Devices
#1

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

#2

Have you got this working? Am working on a project with a current loop and just curious.

#3