Hey Guys,

I built our system successfully using 14 PSXX power districts that are also occupancy zones. Our signals are correctly affected by locomotive current.

I need to send a signal to indicate occupancy. I plan to connect J7-1 (5v) to J4-6 and set up the LED like you indicated. Am I correct in that instance to use the occupied emitter as the output to my signal system? I am presuming occupancy will close the transistor and 5V will be able to be sent as a digital signal and turn on the remote LED indicating occupancy.

Unfortunately, FREDs do NOT cause occupancy to be detected, and I think this is because the block occupancy trip point is too high.

As I understand the documentation, the default for auto-calibration is OFF, and therefore the average unoccupied current is determined by CV56 which is set at a default of 27. If the FREDs are drawing too low a current, occupancy is not sensed, and I believe this is our situation. I think the Freds only draw 2 to 3 mA [milli-amps], but we DO want them to trip occupancy.

I am thinking I should enable auto-calibration, but the other approach is to drop the value in CV56, which will be a trial and error approach. Autocalibration seems like the better approach. What do recommend?

Thanks, Mike D.

Mike:

Try the auto calibration. This will make the PSXX occupancy function as sensitive as possible without false triggers. Like a real railroad, weather conditions (temperature and humidity) can affect the background current, and voltage fluctuations on the track due to current draw will also modify the occupied current; too sensitive and you will get strange false triggers.

If you run into this issue, you can connect a small surface mount resistor across the pick up leads of the FRED. This will increase the current just a bit to give you more reliable triggering. A value of 4.7K with a power rating of 0.1 watts or 0.25 watts will work. Here is an example of the resistor:
https://www.digikey.com/en/products/detail/stackpole-electronics-inc/RMCF1206JT4K70/1753837

The same method is applicable to the PSXX-AR circuit breaker/auto reverser: