National Instruments NI 9214, Operating Instructions And Specifications, Page: 12 / 44

NI 9214 Operating Instructions and Specifications 12 ni.com
Yo u can connect a shielded thermoco u ple to the NI 9214. Connect
the shield to the gro u nd l u g on the NI TB-9214 and COM to a
common-mode voltage reference on the thermoco u ple. A valid
common-mode voltage reference is a voltage that is within ±1.2 V
of the common-mode voltage of the thermoco
u ple. If COM is left
floating, the internal common-mode voltage of the inp u t circ u itry
is the average of all the inp u ts. Refer to the Specifications section
for more information abo u t the common-mode voltage. The shield
gro u nding methodology can vary depending on the application.
Refer to Fig u re 4 for an ill u stration of a typical shielding
config u ration.
Figure 4. Connecting a Shielded Thermocouple Input Signal to the NI 9214
Thermoco u ple
TC–
COM
TC+
S hield
NI
TB-9214
NI 9214
Ch ass i s Gro u nd
Gro u nd
L u g
NI_9214.fm Page 12 Monday, November 1, 2010 9:52 AM