4-4
Cabling and Wiring
Monitoring Contact Closure at an Input
An onboard 10k
Ω
pull-up resistor connected between each channel and
the +5V serves to prevent floating input when contact is open and gives
CMOS compatibility for TTL signals. Figure 4-5 shows how this resistor
makes an input of a PIO-SSR Series board an effective circuit for
monitoring contact closure.
Figure 4-5. Contact-Closure Monitoring at an Input of a
PIO-SSR Series Board
Eliminating Contact Bounce
While you can eliminate contact bounce through your application
program, you can also insert a bounce circuit between the contacts and
the input of your PIO-SSR Series board. Figure 4-6 shows a typical
bounce circuit.
Figure 4-6. Bounce Circuit for an Input of a PIO-SSR Series Board
Switch
10 k
Ω
+5 V
PIO-SSR Series
Board
Digital
Input
#
n
Digital
Common
GND
Onboard Pull-up
Resistor
&
&
10 k
Ω
10 k
Ω
+5 V
TTL
Compatible
AND Gate
Digital
Common
GND
To Digital Input
of a
PIO-SSR Series
Board
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