4.1	Manual fallback

If your computer breaks, if your software is buggy, or if you simply want to sometimes have a fully manual session then it is possible to build a system that supports both worlds.

Assuming that you have taken my advice and used RPC modules for all layout interfacing (power routing, turnout drive, signal drive, sensor inputs etc) then the RPC stack could be connected to either a control panel (using a PTP module) or to a computer (using an RPI or equivalent).

With a PTP, switches on the control panel could drive turnouts (the switch connects to an SRI4 input and its corresponding SRO4 output connects to a PMD module to drive the solenoid motor), switch power to tracks (the output is a relay on a DPR that actually switches the power), turns on lights (the SRO4 can drive lights directly) for example. Also sensors connected to SRI4 inputs under the layout can drive lights on the control panel by using an SRO4 on the panel.

OK, thats too simple I hear you say - I want three control panels to control different areas of the layout. Well you could have three RPC stacks linked to their respective control panels with separate PTP modules. When you want computer mode then you unplug the PTPs and plug in three RS485 RPIs.

Ah, but I want some parts of the layout to be controlled from two (or more) control panels - that is having an overlap between panels. OK thats harder, but its harder to do with any non-computer assisted system. The best bet here is to have an intelligent multi-way PTP that can take inputs from several control panels (possibly linked by RSEs) and can apply some logical expressions to the inputs and route these outputs to the layout as required. Sorry such a module does not yet exist - but its easy to implement with a PC.

The great thing about this possibility is that you can have your cake and eat it. In fact the hardware gives you three modes of operation:

    1. Full PC assist. The computer controls whatever you program it to control.

    2. Intelligent panel routing. the computer controls nothing but simply acts as an intelligent signal router, allowing overlap and interworkiing between control panels.

    3. Non computer mode. Rip out the RPIs and replace with PTPs. If all your computers explode you can quickly drop back to the 'old' way of working.

I suggest that with these options, such an RPC-based layout is ideal for many clubs as it allows everybody to have their way. You can have different evenings for different interests without having to do any rewiring of the layout. Once a layout is equipped with RPC modules (or any equivalent, such as CTI for that matter) then you open up the operating horizons and I suspect that there are other possibilities I have not thought about yet.