The Otis button interface so far....

Do the landing units only have the two button functionality, or other features too?

Big Clive

The RS14 is also used for a multitude of inputs , not just pushes, they are often used for the door open / closed signals from the car DFC DOL as well as inputs from external devices (fire interface etc) The Hall call pushes are actually controlled by another PCB the HBB board which are addressed in the same manor but only have two inputs for up/down call.

From the patent they have introduced priority messaging and individual node messaging onto the standard CAN 2.0 bus protocol. The have also tweaked the collision avoidance due I suspect to the vast number of devices you could have on an elevator network. Probaly what CAN should have been defined as in the first place.

Tokkan FX

I found a variant of the board, RS14, which has the patent number for the communications protocol marked on the uC - https://patents.google.com/patent/US4622551A/en (source: https://www.yoycart.com/Product/564064119430/) That pinout does suggest it's a PIC, and looks to be running at 8MHz in the examples I've seen the same as yours. While different, the copyright date on that one with the patent number is 1992, and looks like a chip date code in '98 which might help narrow it down, but I wonder if hooking up a programmer might enable you to read the device ID .. there's a list here - https://www.microchip.com/forums/m1043033.aspx (ignore the screenshots, there's a plain text file a few comments down)

David Reader

The control signal is a direct link to the microcontroller. With an NPN transistor I'd expect a current limiting resistor.

Big Clive

You might like Probe Master's spring-loaded microtip test leads. They are excellent for probing pc boards. https://probemaster.com/spring-loaded-micro-tip-test-lead-kit/

Real time device control is not my area of expertise but I'm guessing that they might choose a propriety standard, so they are not subject to standard changes outside of their control. As they are unlikely to want to interact with other manufacturers devices this makes sense.

Dr Andy Hill

This QG looks like NPN to me. I can be wrong though. https://www.s-manuals.com/smd/qg I like to use this site for questionable components.

Aleksander

Not sure. It might be for a display.

Big Clive

That's common in carpeted offices. In vintage lifts real shocks from buttons were sometimes down to worn button insulators.

Big Clive

Did you happen to deduce what the other connector below the microcontroller is for?

Cameron Steel

I always seemed to get a static shock every time I pressed the call button on an elevator- now I have a short piece of 4mm brass tube - specifically for pressing the button and not getting zapped!

Mike Hughes

https://www.freepatentsonline.com/5854454.pdf

The function of the door close button can be programmed. My preference is to use it to reset the door open timer.

Big Clive

Were you able to confirm that the "door close" button does, in fact, do nothing? ;)

Nick Loh