Vt1529A/B Bridge Configurations - VXI VT1422A User Manual

VT1529A/B Bridge Configurations

The Quarter Bridge
configuration
8-pin telcom
connector (RJ-45)
Pin 1 +Excitation
Strain
Pin 8
Bridge
+Excitation Sense
Pin 6 +Sense
Pin 3
-Sense
Pin 7
-Excitation Sense
-Excitation
Pin 2
RJ-45 Pin#
12345678
Pin 5 -R Cal
Pin 4
+R Cal
OUTP:SHUNT ON | OFF
Figure 3-10. Bridge Completion for a Quarter Bridge Channel
70 Programming the VT1422A & VT1529A/B for Remote Strain Measurement
Figure 3-10 shows the connections to the 8-pin telecom connector for a
quarter bridge configuration. It also shows a simplified schematic of the
bridge completion settings for a quarter bridge channel.
Quarter Bridge
10k
CAL:REMote?
10k
Wagner
Voltage enable
10k
off for full bridge
10k
350
SENS:FUNC:STRAIN:<br_type>
120
SENS:STR:BRIDge:TYPE
customer
Local Rcal
Enable
Remote Rcal
Int/Ext Rcal
Enable
OUTP:SHUNT:SOUR INT | EXT
Note
While the diagram above shows amplifier gain in the measurement path,
the measurement values returned by these channels are corrected by the
VT1422A's DSP (Digital Signal Processor) chip to reflect the actual value
at the user input terminal. The only time gain must be considered is when
the input voltage times the gain would overload the A/D range chosen with
a SENS:FUNC:... <range>,(<ch_list>) command. For example, with a
gain of 32, any input voltage greater than 0.5 V would cause an overload
reading even on the highest A/D range (16 V).
(channel 0 shown)
Excitation
to CHs 1-7
Current
Limit
Instrument.
Amplifier
+
X16
-
Cal+ Cal-
+Excitation Sense
-Excitation Sense
or
50k
Internal
Rcal
Select
Excitation Sense
from CHs 1-31
SENS:STR:EXC:STATE
+ Excitation
-
Excitation
enable excitation
CHs 0-7
Dynamic Strain
Buffer
X2
INP:FILT:FREQ
CH00
INP:FILT:STATe
CH01
Optional
Filter
Buffer
2,10,100Hz
32:1
X2
Mux
CH00
CH01
CH31
32:1
Mux
SENS:STR:CONNect BRID | EXC
CH31
External customer
shunt cal resistor
Bridge Sense
from CHs 1-31
Output
To VT1422A
(VT1539A SCP)
RJ-45
2:1
Mux
Cal+
Cal-
-R Cal
+R Cal
terminals
Chapter 3