Line sensor wire gauge questions

I’m wondering if it is legal to cut off the PWM pins and soder the line sensor directly to the pwm wire (is the PWM even a legal gauge to connect the line sensor?)

Also, I was wondering if I can run one +12V wire from a 20amp circuit breaker and expose part of the wire, and connect all the line sensors to it.

Dinush,
It is my belief that what you are explaining is legal. The light sensors do need +12 volts and that is not provided by the RC. Running a wire for power from a 20 Amp breaker as a common to all the sensors seems to be within the electrical guidlines. Be sure to insulate the wiring, I suggest heatshrink. Soldering to a PWM cable works, use heatshrink on those connections as well and be sure of your wiring before you power up. You don’t want 12 volts accidently entering the signal pins on the RC.

I was also unsure because I soldered the blue wire in the line sensor to a PWM pin which connects to the Digitali I/O ground, but in the circuit diagram, it shows the line sensor connecting directly to the ground on the circuit breaker.

And in the rule book it says:
“Sensors may not be wired in series with their loads to directlyu control those loads”
Which is why I was wondering about running one wire from the 20amp circuit breaker and cutting off parts off the insulation and sodering the brown wire of each sensor to the +12V wire.

It also says:
“The loads must be controlled by PWM signals sent by the Robot Controller to relays or speed controllers”

What exactly is this reffering to? Does this mean that the power of the sensors has to be controlled by the microcontroller through a relay?

The rule you cited refers to the digital pneumatic pressure sensor and the pneumatic compressor. The reason they have this rule is because, in the past, teams have connected the pressure switch and compressor in series, because they figure that doing so is a lot simpler than setting up the system properly, which involves reading the sensor value into the control system, and having the pneumatic compressor connected to a seperate relay. What they don’t realize is that the compressor draws upwards of 10Amps, and in the setup they have created, 10Amps is also going directly through the pressure switch. The switch itself can be irreparably damaged by passing this much current through it.

I have a vague idea of what you’re saying to do, but this vague idea doesn’t contain anything that strikes me as wrong. And I really trust Al Skierkiewicz’s judgement. :slight_smile:

“I was also unsure because I soldered the blue wire in the line sensor to a PWM pin which connects to the Digitali I/O ground, but in the circuit diagram, it shows the line sensor connecting directly to the ground on the circuit breaker.” The blue wire can go to the ground pin on the RC or to battery common. I found it easier (and more correct for signal) to connect to the RC Ground Pin.

“Sensors may not be wired in series with their loads to directlyu control those loads”
This is to prevent high current from passing through or being controlled by low current devices. It is for your own safety that Banner sensors be used with inputs on the RC and not connect directly to any motor or solenoid.

“Which is why I was wondering about running one wire from the 20amp circuit breaker and cutting off parts off the insulation and sodering the brown wire of each sensor to the +12V wire.”
The brown wire is the +12 volt input to the sensors. You could run a wire from the +12 volt input to the RC for this purpose but I would not. The separate wire and circuit breaker is the best approach. The circuit breaker protects your wiring for the sensors and won’t affect the operation of the RC. Again, don’t forget to adequately insulate your soldered connections when they are complete.

"It also says:
“The loads must be controlled by PWM signals sent by the Robot Controller to relays or speed controllers. What exactly is this reffering to? Does this mean that the power of the sensors has to be controlled by the microcontroller through a relay?”
It means that any motor, solenoid or servo must be controlled by speed controller or Spike only. Since these devices can only be controlled by the RC, then all sensors must be used as inputs to the RC and software must be used to read those inputs and respond with a PWM output to control any of the output devices listed above.

Final note: The Banner sensors have normally open and normally closed contacts which reference to the common or “blue” lead. Your software and connection must match for proper operation. i.e. when the software expects a closure to ground, the sensor is wired with the black lead to the signal input on the RC. Check your software as it controls some of the digital inputs for other functions. (or so I have been told, any software guys can comment on that.)

Thanks for clarifying all of that.

Thanks for the complement! I would prefer that someone question my answers sometimes. I am not infallible. When you question someone’s response and check it out for yourself I think you learn a lot more.
BTW has anyone noticed the Valentine’s Day theme up at the top of the page?