Chapter 4: Excitation Voltage
Sensors that are based on a Wheatstone bridge need an excitation voltage to excite the bridge. The FBDA provides an adjustable excitation voltage. This excitation voltage is available on the terminal block labeled EXV. The excitation voltage is set to 5VDC ± 0.05VDC at the factory. This voltage is referenced with respect to GND. To adjust the excitation voltage, the following steps should be followed:
1.Remove the cover from the FBDA module using a small slotted screwdriver.
2.Make all of the required connections except the sensor connections and turn on the power.
3.Using a voltmeter, measure the voltage on the terminal block labeled EXV with respect to the GND terminal block. Adjust P2 to change the excitation voltage. The terminal block labeled A/D 1 can be used to measure the excitation voltage.
Sensors that are comprised of Wheatstone bridges usually state the amount of output per volt of excitation voltage. An example is: 10mV output / 1V of excitation. If a 5V excitation voltage is used, The full scale output of the sensor will be 50mV. The gain of the FBDA should then be chosen, so that Vout does not exceed 5V (the maximum voltage that the SDAXX line of data acquisition modules can measure).
If for some reason the excitation voltage source in the FBDA does not meet your needs, you can use an external excitation voltage. If this is the case, then nothing should be connected to the EXV terminal block, and the GND lead of the external excitation voltage source should be connected to the GND terminal block on the FBDA module.
Documentation Number FBDA0797 Manual | 9 |
B&B Electronics
PH (815)
