User`s manual

Digital I/O

Activating an Air Valve

Lets say you want to control a air valve for equipment that will automatically stamp “tested

good” on each assembly that passes a test. In the Set Digital Output users preference, you

could select Cable Counted Good to both set and reset the output. Remember that if the same

event is selected for set and reset, the tester will sink the output for a 10-millisecond pulse. In

this case a pulse is all we need to make our stamp mechanism function.

In this example, the solenoid for the air piston requires DC 24 volts and 450 milliamps. Note

the IO port can only supply 100 milliamps at either DC 5 or 10 volts. However the output can

sink up to 24 DC volts. Therefore, in this case you can use an external power supply for the

valve circuit as shown below.

Pin 5

Output

Pins 14 & 15

Ground

Valve

Solinoid

DC Power

Supply

+24 V

Diode

Again in this example, a 1N4002 is added across the relay to protect the IO port from the

reverse current created from the coil when the output turns off.