Chapter 2 System Components Pull-Up Circuitry In some cases, you must add pull-up circuitry to connect an output device to an input signal; specifically, you must attach an external pull-up resistor between the voltage source and the Input pin. This is required when you connect the Input Common pin to the electrical return path and the third-party output device is in a sinking configuration. In this case, select a resistor value that will not overcurrent the output device and instead provide just enough current and voltage to your HAWK MV-4000 input signals, according to the electrical specifications subsection in Appendix C: General Specifications.
Note that you should use a resistor with an appropriate power rating for your circuit. (Equivalent circuit only.) 2-30 HAWK MV-4000 Smart Camera Guide