
Programming the VT1422A & VT1529A/B for Remote Strain Measurement 71
Chapter 3
The Half Bridge
configuration
Figure 3-11 shows the connections to the 8-pin telecom connector for a half
bridge configuration. It also shows a simplified schematic of the bridge
completion settings for a half bridge channel.
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).
Figure 3-11. Bridge Completion for a Half Bridge Channel
Strain
Bridge
8-pin telcom
connector (RJ-45)
Cal-
Cal+
350
120
customer
10k
10k
10k
10k
+
-
Optional
Filter
2,10,100Hz
+Excitation Sense
Instrument.
Amplifier
Dynamic Strain
Output
+ Excitation
-
Excitation
Internal
Rcal
50k
Local Rcal
Enable
Remote Rcal
Enable
Int/Ext Rcal
Select
Excitation Sense
from CHs 1-31
32:1
Mux
CH31
CH00
CH01
32:1
Mux
CH31
CH01
CH00
Bridge Sense
from CHs 1-31
External customer
shunt cal resistor
terminals
-R Cal
+R Cal
enable excitation
CHs 0-7
Half Bridge
(channel 0 shown)
Current
Limit
Excitation
to CHs 1-7
+Excitation
+Sense
-Sense
-R Cal
+R Cal
+Excitation Sense
-Excitation Sense
-Excitation
Wagner
Voltage enable
off for full bridge
-Excitation Sense
X16
Buffer
To VT1422A
(VT1539A SCP)
X2
Buffer
RJ-45
OUTP:SHUNT:SOUR INT | EXT
OUTP:SHUNT ON | OFF
SENS:FUNC:STRAIN:<br_type>
or
SENS:STR:BRIDge:TYPE
CAL:REMote?
SENS:STR:EXC:STATE
SENS:STR:CONNect BRID | EXC
INP:FILT:FREQ
INP:FILT:STATe
X2
2:1
Mux
Cal-
Cal+
Pin 5
RJ-45 Pin#
12345678
Pin 4
Pin 2
Pin 7
Pin 6
Pin 3
Pin 8
Pin 1
Summary of Contents for VT1422A
Page 2: ...This page is blank...
Page 8: ...8 Notes...
Page 22: ...22 Support...
Page 57: ...Field Wiring 57 Chapter 2...
Page 58: ...58 Field Wiring Chapter 2...
Page 96: ...94 Programming the VT1422A VT1529A B for Remote Strain Measurement Chapter 3...
Page 162: ...160 Programming the VT1422A for Data Acquisition and Control Chapter 4...
Page 224: ...222 Creating and Running Algorithms Chapter 6...
Page 419: ...VT1422A Command Reference 417 Chapter 7 Notes...
Page 420: ...418 VT1422A Command Reference Chapter 7 Notes...
Page 425: ...Specifications 423 Appendix A Thermocouple Type E 200 800 C SCPs VT1501 02 03A...
Page 426: ...424 Specifications Appendix A Thermocouple Type E 200 800 C SCPs VT1508 09A...
Page 427: ...Specifications 425 Appendix A Thermocouple Type E 0 800 C SCPs VT1501A 02A 03A...
Page 428: ...426 Specifications Appendix A Thermocouple Type E 0 800 C SCPs VT1508A 09A...
Page 429: ...Specifications 427 Appendix A Thermocouple Type E Extended SCPs VT1501A 02A 03A...
Page 430: ...428 Specifications Appendix A Thermocouple Type E Extended SCPs VT1508A 09A...
Page 431: ...Specifications 429 Appendix A Thermocouple Type J SCPs VT1501A 02A 03A...
Page 432: ...430 Specifications Appendix A Thermocouple Type J SCPs VT1508A 09A...
Page 433: ...Specifications 431 Appendix A Thermocouple Type K SCPs VT1501A 02A 03A...
Page 434: ...432 Specifications Appendix A Thermocouple Type R SCPs VT1501A 02A 03A...
Page 435: ...Specifications 433 Appendix A Thermocouple Type R SCPs VT1508A 09A...
Page 436: ...434 Specifications Appendix A Thermocouple Type S SCPs VT1501A 02A 03A...
Page 437: ...Specifications 435 Appendix A Thermocouple Type S SCPs VT1508A 09A...
Page 438: ...436 Specifications Appendix A Thermocouple Type T SCPs VT1501A 02A 03A...
Page 439: ...Specifications 437 Appendix A Thermocouple Type T SCPs VT1508A 09A...
Page 440: ...438 Specifications Appendix A 5k Thermistor Reference SCPs VT1501A 02A 03A...
Page 441: ...Specifications 439 Appendix A 5k Thermistor Reference SCPs VT1508A 09A...
Page 442: ...440 Specifications Appendix A RTD Reference SCPs VT1501A 02A 03A...
Page 443: ...Specifications 441 Appendix A RTD SCPs VT1501A 02A 03A...
Page 444: ...442 Specifications Appendix A RTD SCPs VT1508A 09A...
Page 445: ...Specifications 443 Appendix A 2250 Thermistor SCPs VT1501A 02A 03A...
Page 446: ...444 Specifications Appendix A 2250 Thermistor SCPs VT1508A 09A...
Page 447: ...Specifications 445 Appendix A 5k Thermistor SCPs VT1501A 02A 03A...
Page 448: ...446 Specifications Appendix A 5k Thermistor SCPs VT1508A 09A...
Page 449: ...Specifications 447 Appendix A 10k Thermistor SCPs VT1501A 02A 03A...
Page 450: ...448 Specifications Appendix A 10k Thermistor SCPs VT1508A 09A...
Page 454: ...452 Specifications Appendix A...
Page 480: ...478 VT1529A B Verification Calibration Appendix C...
Page 484: ...482 Glossary Appendix D Notes...