Driving an industrial device with 4-20mA output

Other Hardware General Electronics
1

Hi all, a friend of mine asked me if it's possible to drive a 24V Proportional Pressure Regulator valve.

The input specs are:

Analog input W- (- setpoint value)
Analog input W+ (+ setpoint value) 4...20mA (PNP)
Input resistance: 250 ohm

and the output is:

Analog output X (actual value)

The product code is:

VPPM-6L-L-1-G18-0L2H-A4P-S1C1

I actually managed to regulate via analog output (1-5v) many times, but never in mA

Do I need an additional circuit?

2

Looks like the valve already has the load resistor and conversion electronics built in, so if 1 - 5 volts works, you're set. (As long as your 5 volts can supply 20 mA without strain or overheating.)

3

outsider:
Looks like the valve already has the load resistor and conversion electronics built in, so if 1 - 5 volts works, you're set.

Do you mean that I could take the yellow analog W+ input and supply voltage to it via digital pin?

4

Do you mean PWM? If so I would low pass filter the PWM with (as a starting point) a 2k resistor between the PWM pin and valve input and a 1uF capacitor from valve input to ground then adjust if needed for lowest ripple with acceptable response speed.
Here's a couple of links that might help:

http://circuitelec.blogspot.com/2009/03/4-20-ma-source-circuit.html

5

Ok thank you very much, I'll get some information on what is supposed to be attached to the valve input. I don't know if is something like a pot or pwm digital or if it's just something that act as a button (+1/-1).

6

outsider:
Do you mean PWM? If so I would low pass filter the PWM with (as a starting point) a 2k resistor between the PWM pin and valve input and a 1uF capacitor from valve input to ground then adjust if needed for lowest ripple with acceptable response speed.
Here's a couple of links that might help:

Low Pass Filter Calculator

http://ekswai.com/en_lowpass.htm

4-20 mA source circuit | Electronic Circuit Directory

The low pass filter will give me a 0-5v range of voltage, is it correct? Is it safe to feed the 4-20ma analog in of the valve with this voltage?

Also, I noticed that there's a digital input, but I suppose it is for something else (it can't be controlled with an arduino).

I honestly feel so dumb :smiley: