PID(INPUT 4-20mA OUTPUT 4-20mA)

HELLO 

I AM WORKING ON A APPLICATION WHERE I HAVE TO CONTROL A FURNACE TEMERATURE WITH THYRISTOR CONTROLLED HEATER(4-20mA).

I AM USING A THERMOCOUPLE TRANSMITTER WHICH HAS A 24 VDC AUX SUPPLY AND 4-20mA OUTPUT(FOR TEMPERATURE FEED BACK). WHEN I MEASURE WITH MULTIMETER TRANSMITTER IS SHOWING CORRECT mA OUTPUT. BUT WHEN I CONNECT TRANSMITTER (+) TO CH1 AND (-) TO GND IT IS SHOWING 1.434 mA AND NOTHING CHANGE WITH TEMERATURE.

 

Ganesh Datt Joshi
Ganesh Datt Joshi
7
| 2 1 2
Asked on 12/6/16, 2:39 PM
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vote
3009 Views

I remember having a similar issue where the ma reading didn't change.

It was fixed by putting

Indio.setADCResolution(16); // Set the ADC resolution. Choices are 12bit@240SPS, 14bit@60SPS, 16bit@15SPS and 18bit@3.75SPS.

in the setup code.

Raghuram Shenoy
Raghuram Shenoy
7
| 4 1 2
Answered on 12/6/16, 3:59 PM
0
vote

Hello,please submit code sample.

I am quite sure nothing is wrong in the hardware, I don't know if your test with multimeter is valid after all when connected to input bias.

If you load Industruino sample program you can see readings on display and check actual readings

 

Stefano Giuseppe Bonvini
Stefano Giuseppe Bonvini
107
| 4 1 3
Answered on 12/6/16, 3:33 PM
0
vote

i connect multimeter in series with ch1. multimeter and analog input showing same mA value.

Ganesh Datt Joshi
on 12/6/16, 3:50 PM

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Asked: 12/6/16, 2:39 PM
Seen: 3009 times
Last updated: 12/6/16, 3:59 PM