Extron electronics IPCP Pro Series User Manual page 41

Flex 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
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+5.0 VDC pull-up resistor.
An external short to ground creates a logic low.
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An open circuit creates a logic high
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Example application, digital input with pull-up: connecting a two-position
•
switch
+5.0 V
SW 2
A/D
CTL
Converter
Figure 30. Flex I/O Digital Input Application:
Two-position Switch With Pull-up
Two-position switch is open: logic high, front panel LED is off.
Two-position switch is closed: logic low, front panel LED is lit.
Digital output — To activate LEDs, control incandescent lights, or power 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
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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
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floats (is not connected).
If the application calls for TTL compatibility, the digital output circuit can be set up
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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 closes, voltage output is 4.3 VDC.
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Each I/O port is capable of accepting 250 mA, maximum.
1k ohms
Flex
I/O
Voltage
SW 1
Protection
GND
IPCP Pro Series • Hardware Features and Installation
Two-position
Switch
33