Temperatures corresponding to voltage ranges with the PXI-4351/TC-2190

[p]

Using a PXI-4351 and TC-2190 with a K-type thermocouple, what temperature range do the voltages (+/- 625 mV, 1.25 V, 2.5 V, 3.75 V, 7.5 V, and 15 V) correspond to? How much accuracy does each different range of voltages have? All I could find was that to get improved accuracy, use a range of 2.5 volts or less (document #1X0F7L3E). Also, will using several channels at vasly different temperatures (ie. room temp. and several hundred degrees) affect which range I should select?

[Brent_R]

The full temperature range of a K type thermocouple from -270C to 1370C represents a voltage range from -6.45mV to 54.8mV. If the only sensors you are using are thermocouples then you should choose the smallest range. The 4351 applies one gain setting to all channels, so the only reason you would want to use anything but the smallest range would be if you have other types of sensors with larger voltage swings. You can find voltages for any thermocouple at any temperature at the link below.

Regards,

Brent R.
Applications Engineer
National Instruments

http://srdata.nist.gov/its90/menu/menu.html