NetBurner and the 4 - 20ma Current Loop

[datamstr]

Hello all,

Has anyone experience or information on using the NetBurner MOD5270 with the 4 - 20ma Current Loop signal?

TIA,
David

[pgmaser]

I have not on the 8270, but on the evaluation board of the 8252 I design a circuit that reads a 4 to 20ma signal into the A/D and displays it through HTTP.

The circuit chip is a RCV420 from TI. It provides a 0 to 5 volt out for 4 to 20ma in.

I working on a converter board that will have eight inputs if you are interested.

Phil

[pgmaser]

Sorry about that I meant 5270 and 5282

[v8dave]

Another option is to simply use a high precision 100 ohm resistor (0.1%) to ground and measure the differential across this resistor with an ADC.

You then get a span of 0.4V to +2V for your 4-20mA input. This is ideal for a lot of ADC's which are 0-2.5V input.

I have used this method with the Microchip MCP3424 ADC which provides 16 bits of resolution at half the price of the RCV420. Actuauly, Phil's choice is ideal if you have the board space and want a span of 0 - 5V without additional op-amps etc and already have an ADC with 0-5V input range.

Cheers,
Dave...