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Digital I/O digital input with pull-up enabled:
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When the port is configured for pull-up, switch 2 is closed, activating the
+5.0 VDC pull-up resistor.
•
When an external switch closes (shorts to ground, logic low), the port is on and
(for the IPL EXP RIO8 front panel only) LED is on.
•
When the external switch opens (logic high), the port is off. The IPL EXP RIO8
front panel LED is off.
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Example application, digital input with pull-up: connecting a two-position
switch
+5.0 V
1k ohms
SW 2
CTL
SW 1
Figure 13.
Digital I/O Digital Input Application:
Two-position Switch With Pull-up
Two-position switch is open: logic high, front panel LED (IPL EXP RIO8 only) is off.
Two-position switch is closed: logic low, front panel LED (IPL EXP RIO8 only) is lit.
Digital output — To activate LEDs, incandescent lights, or other devices that accept
a TTL signal, or to provide contact closure control for projector lifts, motorized screens,
room or light switches via an Extron IPA T RLY4 or similar device, you can use one or
more of these ports as a digital output. When a port is configured for digital output, it
offers two output states: on and off.
•
When the port is set to an "on" state, (the switch 1 circuit is closed), the I/O pin is
connected to ground. Output voltage is less than 0.5 volts.
•
When the port is set to the "off" state (the switch 1 circuit is open), the output pin
floats (is not connected).
•
If the application calls for TTL compatibility, the digital output circuit can be set up
to provide a 2k ohm pull-up resistor to +5 VDC, which you can use if the connected
device does not provide its own power.
If the pull-up resistor is disabled, voltage output is determined by an external
•
source device.
If the pull-up resistor is enabled, switch 2 is closed, voltage output is 4.3 VDC.
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Each I/O port is capable of accepting 250 mA, maximum.
IPL EXP I/O Series • Hardware Features and Installation
Digital
I/O
Voltage
Protection
GND
Two-position
Switch
24
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