Train detection and feedback control with the Lenz System
Film a quick look at the components:
The Lenz feedback system and train detection for PC Programmes
Most PC train automation programmes work in the same way - an overall layout schematic shows all the important features of the layout - points signals and train detection rails. From this information the programme allows you to create routes and in these routes you can specify which points and signals are changed and what happens when the train passes each detection point on that route (Speed up, slow down, stop, change direction, operate locomotive decoder functions among others). You can also enter all of your railed vehicles into a database so the computer can show what it is controlling. It is worth investigating the different programmes out there to get a feel for which would be best for you.
Train detection for a PC controlled shuttle line
We start with a simple arrangement for a popular train automation - a train shuttles between two terminus stations. This can be done with two detection points as in figure 1. How the train behaves can be fine tuned in the PC programme, but it is worth noting that a good positive detection is reliant upon the locomotive pick ups and the cleanliness of the track. You will see that the trains stops at slightly different places each time especially as the running speed of the shuttle increases (Detection may not always be from the 1st axle as it enters the section and the stop command may not be immediately received cleanly by the decoder). More precise control can be achieved by using another detection section to bring the speed down before it enters the stop section (See figure 2).
The Feedback scheme needs to be designed around the trains you wish to run on that track. In the examples above a railcar or a loco hauled train with coach lighting or a cab control car with headlights will be detected and they enter the sections, however a loco pushing un-powered coaches in front of it may only be detected once the loco enters the section so the detection rails will have to be positioned correctly for the train to align with a platform convincingly (See figure 3).
Detection for a through station
Figure 4 shows how to monitor a small station on a line with travel in both directions - it also shows that the PC does not have to use every detection point on a line unless you want to change the state of a train - the route for a through train will ignore the monitored sections.
Block sections allow you to run multiple trains on the same line and avoid collisions. Figure 5 shows a typical set up:
A block section needs to be long enough to hold the longest train running through it - it is also important that that train can be halted, from speed if the next block up the line is occupied. Your PC programme routes settings can allow you to tailor the control of individual trains so that they can behave realistically in a block section system.
Monitored sections and Junctions
Do not put monitored sections across your points (Turnouts). These should be powered from the main track bus. If a point is monitored then the PC programme will show both possible routes as blocked even if only one track is occupied. See figure 6.
Using train detection efficiently
You do not need to wire the entire layout for train detection. You only need detection tracks where you want the behaviour of the trains to change (Start, stop, accelerate, decelerate or control of decoder sound and light functions). In most cases only one detection section is needed, however for more precision you can use more sections. An example of this is a station stop where you want the train to stop precisely alongside a platform - the first detection section will be used to slow the train to a crawl and as soon as it enters the next section a stop command is sent - your locos will then stop at the same position every time. Just bear in mind that the train detection system is the only way that the PC programme can see what is going on with the trains on a layout. The whole system works so long as you tell the PC programme what it is dealing with. The programme relies on being given the correct starting information. The detectors only show if a power consumer is present or absent - as a train progresses through a route each detector will light up in turn until the train reaches its destination. If the routes, track plan and train information is correct at the start then the PC will keep track of everything. If you manually move a loco by hand or using the DCC controller, you must tell the PC programme where it is before you start automatic running again. With that in mind the power consumption detection system is very reliable.
Bi-directional communication such as RailCom offers the possibility of train detection knowing which loco decoder is actually at each detection point. Some programmes already use RailCom or transponders to a certain extent. As yet no programme responds to incorrect decoders turning up at a a detection point - this is mainly because a train can consist of multiple decoders, sometimes with different addresses. It can then become very complex to explain right and wrong detection conditions to a PC so that it can resolve incorrect detections. In most cases a PC programme will throw up an "incorrect loco in section" message and shut down the automation until the issue is manually corrected or overridden.
A quick note on wiring
The feedback system is separated from the main track power in order to prevent interference - the feedback signals are carried back to the R, S terminals on the rear of the LZV200 (or LZV100) command station. In order to keep interference down Lenz advise that you twist the pair of wires that go to the feedback bus. The feedback wires should not be laid parallel to the track bus or live cables - leave a couple of inches distance when channelling the feedback bus wires under the layout. We use 6 amp rated wiring for the track power wiring so that this covers the 5 amp capacity of the system.
Notes on available PC Programmes:
Disclaimer: A& H Models is not affiliated with the following software products however they have had positive reviews so we would like to make Lenz customers aware of them. The links below have contact details for the software publishers - Please make sure that your computer is compatible before making a purchase. The software publishers will be able to assist with any questions you may have.