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11. A quick test of the inputs can made using DIP switch SW1, press key 'G' to set GND/Open
mode, then key 'l' and 'A'. With the jumper SENSOR_BANK_U1 in position 1, set all switches
to ON, this sets all inputs to GND level. Now open switch SW1/1, SENSE1 LED should light.
Carry on opening the rest of the switches, each corresponding LED should now light.
12. The same test can be done for Supply/Open, set jumper SENSOR_BANK_U1 IN position 3,
apply a voltage of 15V to the test point next to J3. Set all switches to OFF, this sets all inputs
to Open level. Now close switch SW1/1, SENSE1 LED should light. Carry on closing the rest of
the SW1 switches, each corresponding LED should now light.
Testing Sense Thresholds
1. In GND/Open mode, VGTHL is 4.5V min and VGTHH is 10.5V max. This can be tested by
connecting a voltage source to the Sensor input pin on connectors J4 and J7. Make sure all
SW1 DIP switches are in the OFF position. Connect a variable voltage source (initially set to
0V) to J4 pin 1, this tests Sensor 1 of U1. Use the short cut 'G' key to program all U1 sensors
to GND/Open, press the 'l' key and then select '0' for sensor 1, the screen should scroll as
shown below, this continually monitors the U1 sensor bank.
2. The screen above is monitoring U1 sensor 1, 0xFE means sensors 2 to 7 bits are at a '1', in
GND/Open, and this means Opens are detected (≥10.5V). Because sensor 1 is held at 0V the
last bit reads '0' or a Closed state (≤4.5V). Now increase the voltage source up to 9V, increase
the voltage slowly, at 10.5V, LED1 on the board should be lit, the screen should now read
0xFF instead of 0xFE. Now decrease the voltage, LED1 should go off before 4.5V is reached.
3. Press any key then press key 'S' to set all sensors to Supply/Open mode. Press the 'l' key and
then select '0' for sensor 1, the screen should scroll as before below but displaying 0x00,
LED1‐8 should be off. Again from 0V, slowly increase voltage until LED1 is lit, this voltage
should be ≤12V, now decrease the voltage, LED1 should go off before 6V is reached.
QSG‐8428‐R Rev. A
HOLT INTEGRATED CIRCUITS
11
Oct 2014
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