PWM Cable Voltage

[Kevin Pai]

Hello everyone, we are using PWM cables to connect to the Roborio colored White, Black, and Red. What is the voltage of each of these individual colored wires?
Thanks, Kev

[Ether]

Originally Posted by Kevin Pai

Hello everyone, we are using PWM cables to connect to the Roborio colored White, Black, and Red. What is the voltage of each of these individual colored wires?
Thanks, Kev

If you want a correct and unambiguous answer, it would help if you would explain why you are asking.

[Kevin Pai]

We need to connect 2 of the 3 cables of the PWM to a limit switch, so that it can connect to the Roboview. We need to find the voltage of the cables so that we can connect the ground cable and the charged one.

[Ether]

Originally Posted by Kevin Pai

We need to connect 2 of the 3 cables of the PWM to a limit switch, so that it can connect to the Roboview. We need to find the voltage of the cables so that we can connect the ground cable and the charged one.

What is a "Roboview"? What is the intended purpose of the limit switch?

[ATannahill]

Please tell us what you are trying to do. I do not know anything about Roboview but I also do not know anything about connecting a limit switch to a PWM port and having a beneficial result. You might need to take a step back and ask a simpler question (i.e. "How do I wire a limit switch?")

A factual answer is that the wires has no voltage. Voltage is the difference in potential energy between two points being evaluated (such as the ends of the wires). For there to be a potential difference you need to have something between the points (a resistor, a capacitor, air, etc.), the wire (while technically a resistor) is not significant enough to cause a voltage between the two points.

The pins on the roboRIO PWM ports do have voltage when compared to the negative input terminal. When the cable is plugged in properly (black on the outside) the black wire has 0 volts, the red wire has 5 volts and the white wire carries a signal voltage meaning it changes between 0 and 5 volts based on software on the roboRIO.

If that sounds confusing, feel free to ignore it and just address my first paragraph.

[Mr V]

The voltage potential you see on each wire depends on what port of the RoboRio you connect it to.

If you want to use a PWM cable to monitor a limit switch you'll want to plug it into a DIO port. Plugged into a DIO port the red wire is 5v the black wire is ground, while the white wire is your signal wire.

You'll want to connect the white wire and black wire to your switch that is activated when pressed. Then in code you want to configure the pin as an input and look for the voltage on the signal wire to go low. There is an internal pull-up resistor so it will show voltage when not connected to ground.

[GeeTwo]

Connected to a PWM port with the standard wire setup, the black wire is the 0V reference, Red is approximately 6V (intended to provide power to servos), and the white wire switches back and forth between 0V and 5V to provide a pulse width modulated (PWM) signal intended to control a servo or motor controller.

[Ether]

Originally Posted by GeeTwo

the white wire switches back and forth between 0V and 5V to provide a pulse width modulated (PWM) signal intended to control a servo or motor controller.

The actual pulse height (in volts) is substantially less than 5 volts when connected to certain models of motor controller.