2 Outputs System Components Connecting to a Digital Device That Requires Two Predictable Voltage Levels to Operate The output signals can only present a low voltage level in a sinking configuration. Their other output state is floating by default. So, if you need to connect to a digital device that requires two predicable voltage levels to operate, pullup circuitry must be added. (Equivalent circuit only.) To add pull-up circuitry, attach an external pull-up resistor. A resistance value of 3 KOhms is suggested to protect your HAWK MV-4000.
Since your HAWK MV-4000 output signals can sink up to 50 mA, use the documentation of your input to calculate the required resistance for your external pull-up resistor (if necessary). In the connections above, the pull-up circuitry causes an inversion if the input of the device is connected to the Output pin. When the output signal is on, the circuit between its Output pin and Output Common pin is closed, and current flows from the power source to the Output Common pin. The observed voltage at the Output pin will be low. When the output signal is off, the circuit between its Output pin and Output Common pin is open, and current flows from the power source to the input of the device.
In other words, the output is active when it is turned off, so the output in the software must be set up as Active Low. HAWK MV-4000 Smart Camera Guide 2-21