I just worte out the whoe thread - pressed 'preview' and the whole thing disapeared !! SO here we go again.

I have 2 M tracks - ' Switching Tracks' 1505.

I was reminded of them when reading the brand new Esu Ecos Detector users manual (just released) today (which I just translated into English while we wait for ESU to publish one) and they show "marklin Switcing Tracks!!! as one option for connecting the Ecos Detector.

Havingnever heard of a Marklin 'switching track' - I looked it up on Google and as soon as I saw a picture I realised I had two. This led also to a very old forum link which I can't track on the forum so have started it again.

In the old thread Webmaster answered but it was not clear to me I am afraid. So I'm asking again - What are these tracks with their two diodes or resistors or whatever soldered underneath and two female plug sockets in the road bed (see attached picture) and how do they work given the two separated isolated middle rail studs (one each joined to a resistor or diode or whatever) are so close to each other.

ESU (and Webmaster) say they can be used for occupancy detection and Webmaster said you need two joined together - but it alludes me why you need two or how they would work. For example - as the pick up shoe passes over the first isolated stud - it must send a signal out via the first socket to the commander or PC via an S88 bus or Ecos detector etc. but that is a 'momentary' switch and once the pick up shoe/slider passes - then what ? For occupancy detection it requires a signal to permanently be sent for as long as the train is in a block ?

In the Esu manual it shows connections from the Ecos detector to both of the sockets - so the train goes over the first one and a second later the next one ???

Any light on this old fashioned BUT possibly useful old M track will be appreciated thanks.

Yes.
There exist a curved one to, same geometry as 5100, called 5104 AFAIR.
The small things are capacitators, mainly to reduce radio interference. As opposed to the ones in supply tracks, thet can be kepted when
running digital.

As Adrian says, the function is that when a wheel axle is present, the isolated rail (and the sockets, and connected s88 / detector is connected to the other rail which is grounded, which makes detector show "occupied".

It's important to understand that all M-track works with the assumption that trackbed is common ground. I don't know how the ECoS detector works; a good guess is that it works well with this track though. But the detector must in that case have some connection to the said common ground.