Parallel light sensors on RCX?

[Duq]

Is it possible to use two light sensors on a single input on the RCX? What I want to do is have two LED/Light sensor combo's to detect passing trains and I only need to know if one of them has been triggered, not which one.

[Toastie]

@Duq

Good evening.

Just tried it out. What works (also with more than 2 light sensors on one port): Put sensor port into passive mode ("none" in BricXCC) and select "raw".

With one sensor I get a reading of about 490 for dark and 380 for rather bright light. With three sensors this gives 450 for all dark and 380 again for bright light on an individual sensor. Which means that the span between dark and light decreases a little. But it works fine, when the light hits the sensor spot on. Setting the "percent" output works as well - numbers are between 88 (dark) and 100 (light) then. These all depend highly on your setup but in essence I believe it works.

With the sensor LED powered ("reflection" mode, sensor LED on) I could not get it to work - the sensor electronic circuity may not like to run in parallel.

I bet that @Philo knows exactly why this is.

Whatever it is worth.

Best
Thorsten