Connecting to the auxiliary I/O interface 39
To add pullup or pull-down circuitry, attach an external pullup or pull-down
resistor, respectively. A resistance value of 3 KOhms is suggested to protect your
Matrox Iris GTR. Since your Matrox Iris GTR auxiliary output signals can sink
up to 50 mA, use the documentation of your input to calculate the required
resistance for your external pullup/pull-down resistor (if necessary).
In the connections above, the pullup circuitry causes an inversion if the input of
the device is connected to the AUX_OUT pin. When the auxiliary output signal
is on, the circuit between its AUX_OUT and AUX_OUT_COMMON pins is
closed, and current flows from the power source to the AUX_OUT_COMMON
pin. So the observed voltage at the AUX_OUT pin will be low. Whereas, when
the auxiliary output signal is off, the circuit between its AUX_OUT and
AUX_OUT_COMMON pins is open, and current flows from the power source
to the input of the device. In this state, the current is limited by the pullup’s resistor
value.
Warning The Matrox Iris GTR auxiliary output signals are compatible with voltages up to
24 V. However, by default, the auxiliary output signals offer low resistance. When
they are on (their circuit is closed), current flows directly through them. Ensure
that the circuit created between the power source, the output signal, the connected
device, and return path does not cause more than 50 mA to flow through the
signal.
As a precaution, the auxiliary output signals are individually fuse-protected up to
50 mA. Matrox Iris GTR uses resettable fuses. The fuses protect Matrox Iris GTR
if you accidentally connect their corresponding auxiliary output signal to a device
that sources/sinks more current than Matrox Iris GTR can safely transmit. If more
than 50 mA of current goes through your Matrox Iris GTR, the fuse will
eventually trip. After disconnecting your Matrox Iris GTR, the fuse will reset only
after it has sufficiently cooled,
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