4-20ma Rescaling
Hi, I currently have a transmitter supplying 4-20ma signal to a propotional valve that act as receiver. I would like to use IND.IO to filter the signal sent by transmitter. I wish to read the 4-20ma signal from transmitter for one minute and send the average value to receiver and I am thinking to use IND.IO as the processing bridge. However, per my understanding, this will require two isolated circuit between the analog input and analog output. I tried to measure continuity between the two common ports in the analogue section and found they are connected. Is it possible to do it?
Hi Tom,
Thank you for your reply. I got it working already but the funny part is when I use: Indio.analogWriteMode(1, mA_p); and call: Indio.analogWrite(1, 100, false); in the loop, the output is only 10.7mA ( 42.5 % ). Isn't it suppose to output 20mA (100%)? I tried using: Indio.analogWriteMode(1, mA); and call: Indio.analogWrite(1, 20, false); I get 20.5 mA. I measure them using Sanwa PC-7000. The mA output mode is working correctly but not the mA_p. Anybody know what did I do wrong?
Hi Albert,
You will use an Analog IN channel, and an Analog OUT channel, and indeed they share GND, so your transmitter and receiver will have a shared GND. The 2 circuits will have different signals based on your codel they do not need to be isolated for the purpose you descrived.
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| Asked: 10/9/16, 5:36 AM |
| Seen: 2991 times |
| Last updated: 10/9/16, 2:46 PM |
Hi Albert, there seems to be a mistake in the Indio library for option mA_p, so i advise you to use the other modes mA and mA_raw. To get the most accurate results, you need to calibrate your IND.I/O as described here https://industruino.com/blog/our-news-1/post/ind-i-o-analog-calibration-18