can i use a tc-2095 to read any voltage signal?

[superspy]

I have a Rosemount pressure transmitter, which gives a 4-20mA signal and is wired up to a resistor so that I can measure the voltage output across it.  Is it possible to use the TC-2095 to read this voltage as I have one available to use and would prefer not to have to order new equipment due to time constraints.  I know it is supposed to be for thermocouples but seen as I'll be measuring voltage anyway would it be alright to use?

[KostasB]

Hi,

the TC-2095 is  a connector block- which module are you connecting to? In principle, you should be able to use the same module as thermocouples also output mVolts. A few considerations:

1) Input range: make sure you don't exceed the input range of the module. Thermocouple modules usually have a 100x1 gain amplifier so you may need to disable that by setting your tasks accordingly.

2)CJC- Cold Junction Compensation must be programmatically disabled as it is only used for thermocouple measurements.

3) Thermocouple modules usually have a 2Hz low pass filter which you may also want to disable if you are interested in higher frequency responses.

Thanks,

KostasB

NI UK Applications Engineering

[Logan_K]

Hi,

This should work, but the only thing that you would probably need to worry about is the configuration of the pull-up and ground reference resistors that are built in. If you enable the pull-up and the ground reference resistors (using the DIP switches on the rear), you may add errors because of current leakage - which is up to 0.5uA depending on which bias resistor is installed. You can disable these, but you may need to consider your ground reference depending on how the transducer is referenced.

You should refer to this user manual for more details:
http://www.ni.com/pdf/manuals/321731b.pdf

Regards,
Logan K