I am trying to use your 4 channel 4-20 mA Transmitter and I observe this behavior:
- When I connect a single channel (any of 4 1-4 channels) using a DC external supply + a load on CTO1, every thing works fine
- When I am trying to connect/use a second channel using a second load but sharing the same DC supply on CTO2, I observe a major impact on CTO1 reading value!
I made test with several different supplies with same result
The only way where I got a good result was:
- Using 2 different supply for CT01 and CTO2
- Using to mA meter to observe the current
Do you have an idea of the problem?
Do you have a typical wiring example?
You cant use same power supply for multiple channels. the reason is this
lets say you connect a power supply to channel one and control the 4-20mA output, it will work fine. now lets say you use the same power supply with 2 channels and change the 4-20mA output of channel 2, it will also change the power supply current on channel one, because it will create a close loop for ch1 as well as ch2.
How many channels do you want to use with signal power supply ?
We want to use 4 channels per supply
You can use 4 of these
with a I2C mux
this setup will let you use one power supply with all 4 channels.
I want to be sure that you understand my setup, as described in picture attachment, my supply is connected in parallel so I am not sure to understand why ch1 and ch2 are not totally independant even sharing same supply:
when loop one is active it will feed signal in the ch2 and this will cause false readings on the ch2.
You can try adding diodes and see if that separates the 2 loops. i never tried it but there is no harm in trying.
I have tried diodes and solution doesn’t work
I bought 6 modules (4 channels) to do my job but it is not woking…
Is it possible to have some credit for the quad module since it is not usable and I gave to replace each of them with 4 single channel?
please contact at firstname.lastname@example.org.
(We are a custom manufacture and generally dont accept return of more then 5pcs of same board, but in this case we can workout something for you.)