VXi VT1422A 사용자 설명서

Verifying bridge configurations and connections is accomplished by 
inserting a known resistance (shunt cal resistor) in parallel with one leg of 
the bridge to imbalance it by a predictable amount. The VT1529A/B 
provides a single, internal 50 k

Ω shunt cal resistor that can be 

programmatically connected to each of the 32 channels, one channel at a 
time. The VT1529A/B also provides the same connection capability for an 
optional external user supplied shunt cal resistor. The user’s shunt cal 
resistor can be connected via the front panel "Shunt Cal Resistor" terminal 
block. See Figure 3-19.

For the following discussion, refer to Figure 3-10 through Figure 3-12. 
The OUTPut:SHUNt:SOURce  INT | EXT,(@<ch_list>) command selects 
either the INTernal (built-in) or EXTernal (user supplied) shunt cal resistor. 
Use the OUTput:SHUNt ON | OFF,(@<ch_list>) command to actually 
connect the shunt cal resistor to the bridge to be tested. For OUTP:SHUN, 
<ch_list> may specify only a single channel on any one VT1529A/B. This 
is because a single resistor is used to shunt each of a VT1529A/B’s 32 
channels. When the command is sent to connect another channel, the 
previously closed channel is opened. 

To perform shunt cal on multiple channels, the program will have to enter a 
loop to connect the shunt cal resistor to sequential channels and read the 
result from the shunted channel. Generally, only OUTP:SHUN OFF needs 
to be sent to open the last channel closed on a particular VT1529A/B. For 
quarter bridge completion, the shunt cal resistor is connected locally 
(on-board the VT1529A/B). For both half and full bridge completion, the 
shunt cal resistor is connected remotely via the -Real and +Real terminals. 
The switches that route Real are automatically controlled by the bridge 
configuration commands [SENSe:]FUNCtion:Q120, 
[SENSe:]FUNCtion:Q350, [SENSe:]FUNCtion:USER, 
[SENSe:]FUNCtion:HBEN, [SENSe:]FUNCtion:FBEN, and 
[SENSe:]STRain:BRIDge[:TYPE].

See Figure 3-20 for a general shunt cal programming sequence. A C++ 
example source file (shuntcal.cpp) is available in the VXIplug&play help 
file and on the CD supplied with the instrument. View the readme.txt file 
provided with the VXIplug&play driver for example program file location.

Shunt

Cal

Resistor