I have faced an issue with reading a 4-2 mA signal coming form a gas sensor in ABB control panel. Here is the story to share about this small project:
There are two signal splitters coming from our gas guard panel that bring 4-20 mA signals in our ABB control panel. This is a nonpowered loop device since the splitters are powered within the gas guard panel. I have configured the hardware and IO settings in the ABB software and connected the wire leads based on the panel drawing, which I have attached here. Despite this, I am facing an issue where the only reading I am receiving on the raw inputs is constant -32768.
I need assistant with GG-FMA-1002 and GG-MECH-1001. Please note that the H- leg has 24 VDC and as mentioned earlier, the signal repeaters are powered from the power source inside the gas guard cabinet. The two wires landing into the ABB control panel are only 4-20 mA. That is why in my design, I only connect them to the M and L legs. I also removed the 0 VDC voltage reference on the L legs. Can someone review the drawing and let me know if the wiring diagram is correct? I will really appreciate it.

 

Please provide more information. Are they signal splitters or signal isolators? What is the make/model of this device? Disconnect the wires from the + and - terminals on the device and measure DC voltage on these terminals, should be around 24VDC if this has it’s own power supply.

 

I do not see any connection on the analog input card for the negative connector.
the 420 mA signal must go in the + and out the - of the analog card.
I am assuming the inputs are isolated so each channel neg needs to be connected to common.
Hope this helps.

 

Let's start at the very beginning:

With the signal source disconnected from the isolator/splitter, can your DVM (milliamp mode) measure a valid 4-20mA signal?

With the signal source reconnected to the isolator/splitter, but disconnected from the 16 ch AI card, can your DVM (milliamp mode) measure a valid 4-20mA signal coming out of the isolator/splitter module?