Extron electronics IPL EXP I/O Series User Manual page 32

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.
Each I/O port is capable of accepting 250 mA, maximum.
IPL EXP I/O Series • Hardware Features and Installation 24