Hi,

I have a question about how to connect some 4-wire sensors (flow transmitters) to an analog input module. The problem is that the module (ABB AI810 wth TB810 connector) is single-ended, thus all channels' negative terminals are short-circuited. Is it still possible to use it? I mean, are there any problems (damage, or measure errors) interconnecting all the low signal wires of those sensors once they are 4-wired?

 

When you say 4 wire transmitter, do you mean 2 wires for power and 2 wires for output (as well as the 2 wires for the pickoff), or are you counting the 2 wires from the pickoff as 2 of the 4 wires? Single ended input measurement systems are very typically used for measuring 4-20mA signals. How you wire the combined materials, will depend on the type of transmitter you use, loop (output) powered or 4 wire (seperate power terminals from output) powered. If you look at the 4-20mA wiring example at http://www.robertoweninc.com/applic...4-20ma/resistance/thermistor/roi-usb-xma.html you will see the example of a 2 wire circuit for a transmitter with a total of 4 wires (loop and sensor) but this is not what you would call a 4 wire transmitter.

Many 4 wire (seperate power terminal from output) transmitters can be connected to single ended systems, as long as the output (-) does not have a voltage potential when measured to the transmitter supply (-). If it does, you may need to add an isolator.

If you can tell, me a little more about the transmitter (post here or email me a link to the specifications). I will try to determine if you need an isolator and help select one.

You can reach me through http://www.roi-instruments.com and clicking on "Contact Us".

Regards,
Tech