Originally Posted by: WetterauSüd 
Group 1 vs. Group 2 -- I can't figure this out. I've searched the web. I've no luck distinguishing "Formhauptsignal" from "Hauptsignal". I've used the optometrist method of switching between the top sheets of the pdf files -- can't see a differnece.
My questions are these:
Narrow vs. Lattice mast -- is this simply a design aesthetic? If not, when should one choose one over the other?
single vs. dual signals -- what is the appropriate use-case for either these signals?
What is the difference between Group1 & Group 2?
Hello,
Even though I only use Viessmann semaphores, which are a bit different, I took a look at these Marklin products and can offer my take. The only difference that I noticed between Group 1 and Group 2 is that Group 1 only specifies "MFX" vice Group 2 specifies all digital protocols (FX, MFX and DCC). There could be something else that I missed.
As for your other questions:
"Narrow vs. Lattice" -- cosmetic difference (Era and/or location).
"Single vs. Dual" is more complex. Note: For this explanation I will use the following convention: 0 degrees = pointing up and 180 degrees = pointing down.
A "single" arm semaphore is used to indicate "red" or "green" (i.e., stop or proceed). Display is as follows:
(1) arm is at 90 degrees = stop.
(2) arm is at 45 degrees = proceed.
A "dual arm" semaphore can have either: (A) "interconnected arm movement" or (B) "independent arm movement".
(A) If the arms are "interconnected", then the semaphore can indicate only two positions, either "red" or "yellow" (i.e. stop or proceed with caution). Display is as follows:
(1) top arm is at 90 degrees and bottom arm at 0 degrees = stop.
(2) top and bottom arms are both at 45 degrees = proceed with caution.
(B) If the arms are "independent", then the semaphore can indicated three positions, either "red" or "yellow" or "green" (i.e., stop, proceed with caution, proceed). Display is as follows:
(1) top arm is at 90 degrees and bottom arm at 0 degrees = stop.
(2) top and bottom arms are both at 45 degrees = proceed with caution.
(3) top arm is at 45 degrees and bottom arm at 0 degrees = proceed.
As a side note for digital use: a "single arm" or "dual interconnected arm" semaphore requires one digital address to control its two aspects. However, a "dual independent" arm semaphore requires two digital addresses to control its three apsects.
I hope this sheds some light. Again, I don't use Marklin semaphores, but the principle should be the same.
Cheers,
Andry
