Reading 4-20ma

• Reading 4-20ma
  Posted by hubsy on 03 Apr, 2021 15:19
• I have a project where I need to break into an existing 4-20ma control circuit (24v).
  
  I've looked at these,"HW-685 0/4-20mA to 0-3.3/5/10V Voltage Transmitter Signal Converter Module", but as I have found out, these are Non-isolating. The gnd of the current loop is connected to the gnd of the suppling voltage.
  
  So I need a board where the current loop is fully isolated from the board supply.
  Looking through ebay, some adverts say isolation, but looking at the pcb trackside, they appear not to be.
  
  Has anyone found a true isolation board?
• #1 Reply
  Posted by IanJ on 03 Apr, 2021 17:57
• Hi,
  
  Look up Pepperl & Fuchs or Moore Industries.
  Both of them do signal isolators, converters & interfaces for 4-20mA signals.
  
  Ian.
• #2 Reply
  Posted by Tomorokoshi on 03 Apr, 2021 18:16
• Quote from: IanJ on 03 Apr, 2021 17:57

  Hi,
  
  Look up Pepperl & Fuchs or Moore Industries.
  Both of them do signal isolators, converters & interfaces for 4-20mA signals.
  
  Ian.
  

  
  Something like this:
  
  https://www.pepperl-fuchs.com/usa/en/classid_2516.htm?view=productdetails&prodid=9830#overview
• #3 Reply
  Posted by JamesAus on 04 Apr, 2021 05:49
• One I have used many times is the Datexel DAT511. It's loop powered so no additional supply required.