User Manual Owner's manual

Publication 1746-UM007C-EN-P - July 2004

Overview 1-7

Linear Millivolt Device Compatibility

A large number of millivolt devices may be used with the 1746-NT4

module. For this reason we do not specify compatibility with any

particular device.

However, millivolt applications often use bridges of strain gages. To

allow the NT4 Series B (or higher) to operate correctly, the analog

common (

ANALOG COM) terminal of the module needs to be biased to a

level within 2V of the signal of interest. A resistive voltage divider

using 10k Ω resistors is recommended to accomplish this. The circuit

diagram below shows how this connection is made.

ATTENTION

The possibility exists that grounded or exposed

thermocouples can become shorted to a potential

greater than that of the thermocouple itself. Due to

possible shock hazard, care should be taken when

wiring these types of thermocouples. Refer to

Appendix D for more details.

ANALOG COM

fixed

variable

fixed

INPUT

(CHL0, CHL1,

CHL2, CHL3)

Vcc

10k

Ω

10k

Ω

NT4

Strain

Gage

Bridge