Hi all,

I was confused by the Digital handbook a bit.

It's about the Request & Release inputs of S88. Is the "Release" has to be done by level trigger? ie. eg, a contact track or current sensing.
What about Edge triggers like the pulse of a circuit track ?

Let consider a staging yard control, once a yard was occupied, the contact track will provide a level signal to the Release input. This I can understand, further triggers to the Request input will be prohibited.

Now , if I use a circuit track instead to send a pulse to the Release input,once a shoe pass through the track. Can I achieve the same purpose?

I hope I have made my question clear and sensible.

Thanks

Eric

Well,
I share Erics confusion. I've read the instructons for the memory, and not understood. From memory, three s88 may be connected, which function as Dale says, but half of the connections of the s88 are used for request, half for release, and I don't fully understand how. It's certainly about locking established routes just in real life, but how is it done? Really doesn't matter; I like LocoNet things better, but nevertheless, always interested.

/Lars

Hello Eric,

Is your question related with using the marklin MEMORY (6043).
I am using S88 modules with a memory in interlocking mode (i think its called)...to control my 2 shadow stations.

If so I can tell you how I programmed this so that a train entering the shadowstation always enters an unoccupied track and sends another train out of the shadow station.

Hi Eric,

1) A Pulse to the Request input can cause the Memory to execute a preset route. Correct ?
Yes. I personally use a piece of contact track but a pulse should suffice.

2)So I can thing of the Request input as an Interrupt,causing a certain routine to run. Correct ?
Yes. You can also try to activate more than 1 Memory function if you connect more then 1 request input to the device that provides the pulse. I use this so that the input request for the staging yard tries to request routes A1 through A4. Only the first route that is not 'locked' by a release request via a train in the staging yard will activate. It is also importent to know that if you try to activate more than 1 route (exm. A1 through A4) then only the first one that is not blocked by a release input will be selected.

3) Once a Request is acknowledged by the Memory, further Request will be ignored. Until it is "Released", So it's like the Interrupt is MASKED once triggered, correct ?
Yes. Once a certain route is triggered it will not activate again until it is released.

4) My confusion is how that Release is done. In a typical stage yard configuration, assuming a contact track is used, then a parked lok will produce a constant level signal to the Release input(when connected) , and according to the Digital Handbook, this will prevent this particular Request-Release route to be executed. Fine so far.
And once this lok is moved away, this Request is once again open, like the interrupt is unmasked. Correct?
Yes. In my example I request routes A1 through A4. If any train in the station is holding the contact track active (connected to the corresponding release inputs these routes will not activate through the corresponding request input. As soon as the train leaves the contact track the release input trigger is removed and this route can be selected again.

5) So can I think of the Release is trigger by the falling edge, as when the lok leaves the contact track, the Release input drops in signal level ?
Not what I think. The release is activated as long as the train occupies the contract track section in the staging yard by connecting the corresponding input to track mass. But it depends on what you define as 'falling edge'.

6) If 5) is positive, then Contact track is the only option in laying the staging yard, circuit tracks won't work in this case. Circuit track can only indicate a lok has passed, NOT sure if it's still there. Right?
Yes. As you only use a circuit track the release contact is only triggered when a sleeper passes over this track. For the staging yard to function you should use contact tracks so as long a train is parked there this route into the station cannot be selected to avoid collisions.

Hopefully this clears things up a little.

Hi Eric,

Glad I could be of some help. It took myself a lot of experimenting before I began to grasp the logic of using the memory in 'locked' mode.

Now to your question of the 'unfilled requests"
When the staging yard is full and all contact tracks are occupied and an incoming train requests a route none is selected because all are blocked by the 'release' requests from the contact track.
Also this request will not be remembered by the memory.

So it also depends if your input-request to the staging yard is generated by a circuit track (single pulse) or a contact track.

This single pulse is not remembered once the sleeper of the train has passed the circuit track. I think this also applies to a contact track as the input is triggered when the request input is connected to the mass.
But to be sure I have to test it on my own staging yard. I will test this hopefully in a few days when I have the time and report back to you.

I only use contact track because I want to avoid multiple requests when a passenger train with interior passenger car lighting and sleepers triggers the request contact multiple times.

Hope this helps you any further in understanding how the memory works.

Thanks again Jos.
As you may see my other post "Contact Track Length", I have a very clear picture now of what's going on. I need some time and experiment with the memory to find out what it can do. I appreciate your effort very much.

On my "Memory", both Extern and Off is ON when powered up, and I've never programmed anything into it yet.

Be gone for a week, see you later.

Eric