- Mar 30, 2011
I guess the older sets did not use software for control and there was often also no or only severely limited feedback from the controlled unit to the controlling unit. I think on the old Dutch trains there was a single red light on the engineer's console that was labelled something like "malfunction on controlled unit" (in Dutch of course) and then it was the engineer's task to figure out what that malfunction might be (or even which unit it was occurring on). Sometimes a reset would suffice to clear a pertinent malfunction with nobody being any the wiser.Never seen much more then that other then in England and the Netherlands, where I've seen videos, pictures, and even have pictures I've purchased myself of trains made up of up to five multiple units in one train. Of course that was with older multiple units, as newer trains over there seem to be with the standard of many European railroads of having either a long trainset, or 2-3 shorter trainsets to form a service.
The number of units that could be controlled, or the length of the train that could be controlled, was thus essentially limited only by attenuation of the control signals along a not very well EMC-protected cable connected using sometimes dirty or corroded contact sockets between units. But with rather robust low frequency pulses being used for the controls, there was plenty of reserve.
On a software based system, the number of units that can be controlled can sometimes be limited by very trivial things such as the number of software addresses that are available or how they are allocated or even the compatibility of different software versions and how these talk to one another. These can equally be fixed by essentially trivial programming (comparatively speaking) should there be a need. Its just that nobody has so far ever had a need to run three or more ICE sets together for example.