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Originally Posted by maddoctor90
You can run an external circuit to power the 12V sensor and not use the digital sidecar power. You will then need to attach a pull down resistor between the signal going into the sidecar and ground. See the pull down resister configuration in http://en.wikipedia.org/wiki/Pull-up_resistor for more information on what I am talking about. The sidecar is simply an IO interface to the 9403 module. Thus the data sheet here http://www.ni.com/pdf/manuals/374069e.pdf will tell you that you the module is protected for up to +- 30 Volts. |
There is a 10k resistor from each DIO signal pin to the Digital Sidecar's 5V supply. Connecting 12V to that pin is not recommended.
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The AB photo sensors (npn) available from FIRST Choice will feed 12 volts signal into the digital sidecar and I have not heard of any teams having any problems with them, so I think you will be fine feeding a 12V signal to your digital sidecar.
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The NPN sensors do not source any voltage at all, much less 12 volts. They are the equivalent of a simple switch that is either open-circuit or closed to the power return (ground). That's basically what the Digital Sidecar was designed to connect to.
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In fact, we are currently using a 12 volt PNP prox using the configuration I just described. I would like to comment though, if you use a 12V sensor and your battery voltage drops below 12V, the sensor will turn off.
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The 12V optical sensors provided in the 2011 Kit of Parts will work down to at least 10.5V. Some nominally 12V sensors are spec'd to function at 9V.
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Also, you need to make sure not to have your pull down resistor (a custom circuit) off of the same breaker powering the sensor, as this would be a violation of R47.
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Can you explain why you believe <R47> applies to a pull-down resistor in a custom circuit?