VXi VT1422A Manual Do Utilizador

         

The 200 k

Ω resistors in the recommended divider circuit were chosen so that 

the V

SENSE

 output voltage from the 5 k

Ω reference thermistor will be less than 

0.5 V over the temperatures above -15 °C with an excitation voltage of 5 V 
or less. (0.5 V is the maximum input voltage that is allowed between the 
Sense + and - terminals of the VT1529B.) The thermistor compensation 
routines in the VXIplug&play driver assume that the sum of the two resistors 
is exactly 400 k

Ω. The SENS:REF:THERM:RES:POST command can be 

used to specify the actual total resistance value in the divider circuit.

If the combination of excitation voltage and isothermal temperature range 
produces divider output voltages greater than 0.5 V, change the resistor 
values shown to keep the output voltage below 0.5 V. Also, use the 
SENS:REF:THERM:RES:POST command to specify the sum of the 
resistor values so that the compensation routines will work correctly.

Thermistor

+

-

V

SENSE

-

V

EXC

Suggested Wiring for Thermistor Measurement

Note: V

 should be balanced with respect to ground

SENSE

200 k

200 k

+

Ch16
Sense +

Ch17
Sense +

Ch18
Sense +

Ch19
Sense +

Ch16
Sense -

Ch17
Sense -

Ch18
Sense -

Ch19
Sense -

Ch20
Sense +

Ch21

Sense +

Ch22
Sense +

Ch23
Sense +

Ch20
Sense -

Ch21

Sense -

Ch22
Sense -

Ch23
Sense -

Ch20
Ex.Sense +

Ch20

Ex.Sense -

Ch22
Ex.Sense +

Ch22
Ex.Sense -

Ch16
Excitation +

Ch16
Excitation -

Ch18
Ex.Sense +

Ch18
Ex.Sense -

Ch24
Sense +

Ch25
Sense +

Ch26
Sense +

Ch27

Sense +

Ch24
Sense -

Ch25
Sense -

Ch26
Sense -

Ch27
Sense -

Ch28
Sense +

Ch29
Sense +

Ch30
Sense +

Ch31
Sense +

Ch28
Sense -

Ch29
Sense -

Ch30
Sense -

Ch31
Sense -

Ch28
Ex.Sense +

Ch28
Ex.Sense -

Ch30
Ex.Sense +

Ch30
Ex.Sense -

Ch24
Excitation +

Ch24
Excitation -

Ch26
Ex.Sense +

Ch26
Ex.Sense -

Thermistor

Center Sense +

Thermistor

Center Sense -

Thermistor

Right Sense +

Thermistor

Right Sense -

Ground

Trigger