VXi VT1422A 사용자 설명서

This test verifies the operation of the switches associated with the front panel 
Shunt Cal Resistor port. The operation of these switches can be verified by 
observing the changes in the bridge output voltage when external shunt 
calibration is disabled and enabled.

A 1 k

Ω external shunt resistor is connected to the Shunt Cal Resistor port 

and the Dummy Load is attached. The 350

Ω bridge completion resistor path 

is configured. With the external shunt disabled, the bridge output voltage 
should be:

V

sense

 = V

excitation

 * (10 / (10 + 7.5 + .350) - 0.5)

With V

excitation

 = 5.0 V, the expected value of V

sense

 is 0.301120 V.

With the external shunt enabled, the bridge output voltage should be:

V

sense

 = V

excitation

 * (10 / (10 + 7.5 + R) - 0.5)

Where R equals the parallel combination of the 350

Ω resistor and the 1 kΩ 

external shunt or 259.26

Ω.  Again, with V

EXCITATION

 = 5.0 V, the expected 

value of V

sense

 is 0.315433 V.

Note that the actual measurements will vary based on the actual resistor 
values in the dummy load, so these values should be considered approximate 
when running this test.

The VT1529A/B must be connected to the VT1422A through the VT1539A 
SCP. The Dummy Load must be connected to the channel(s) being tested.

The Voltage Source must be connected to the appropriate channel bank 
terminals of the Bridge Excitation input on the VT1529A/B.

The signal path through the VT1529A/B is highlighted in Figure C-5.

If necessary, send the *CAL? query to the VT1422A (required if more than 
8 hours has elapsed since the last *CAL? command). The expected return 
value is “+0”.

Set the Voltage Source to 5.000 V.

Configure the VT1529A/B for 350

Ω quarter-bridge operation using the 

SENS:FUNC:STR:Q350 (@<ch_list>) command. Disable shunt 
calibration by sending the OUTP:SHUNt OFF,(@<ch_list>) command. 
Send the MEAS:VOLT:UNStrained? (@<ch_list>) query to the VT1422A. 
The expected return value is ~0.301 V on each channel. Now, configure 
for external shunt using OUTP:SHUNt:SOURce EXTernal,(@<ch_list>).

For each channel (each must be tested separately), enable external shunt 
calibration by sending the OUTP:SHUNt ON,(@<channel>) command. 
Note: this turns off the shunt on the previous channel. 
Send the MEAS:VOLT:UNStrained? (@<channel>) query to the 
VT1422A. The expected return value is ~0.315 V on each channel.