Dynamic Strain Port Offset Control - VXI VT1422A User Manual

Dynamic Strain Port
Offset Control
Chapter 3
Each buffered dynamic strain channel includes an offset adjusting DAC
controlled by the command
SOURce:VOLTage[:AMPLitude] <-offset_v>,(@<ch_list>)
Reducing the unstrained bridge offset voltage at the dynamic strain port
channel can allow the VT1432A to measure the channel using a more
sensitive range. See Figure 3-14 for the offset DAC arrangement.
Instrument.
Amplifier
+
X16
-
2,10,100Hz
To reduce the offset voltage at each dynamic strain "Buffered Output"
channel:
1. Measure an unstrained Buffered Output channel with a
VT1432A/33B and place the value in a variable arbitrarily called
<offset_v>.
2. Send minus <offset_v> to that channel with the SOUR:VOLT
command. For example: SOUR:VOLT <-offset_v>,(@10000)
Note
With a 13 mV resolution, the offset DAC can reduce the Buffered Output
channel offset to within a few millivolts of zero.
Programming the VT1422A & VT1529A/B for Remote Strain Measurement
Channel Buffer
X2
8-bit offset
DAC
CH00
CH01
Optional
Filter
32:1
Mux
CH31
Figure 3-14. Dynamic Strain Offset DAC
Dynamic Strain
Buffered Output
SOURce:VOLTage
To VT1422A
(VT1539A SCP)
Buffer
RJ-45
X2
2:1
Mux
Cal+
Cal-
75