Technical Mini-Rally

[Gil_J]

Al,

Good points. There are few things in the Prevost multiplex system that an owner can service and fewer things they can actually troubleshoot. The good news is that a lot of diagnostics is built into the architecture. The other good news is that multiplexed systems have been around for decades, even in the automotive industry. I worked on multiplexed communication systems in the early 70s and they weren't new then. What has evolved is the number of interfaces that support a multiplexed system.

At the heart of every Multiplexed systems is a processor that allows multiple connections to share a common connection. This can be time and address based, like your engine's DDEC or even the internet, or they can be shifted in frequency like old phone systems or your FM radio. Today, with few exceptions, multiplex systems assign the end system or device a unique address. The interconnecting systems now have their own protocol that helps ensure every connection request is satisfied.

Take Marathon's TechLink, which is more of a marketing name than anything. TechLink used to have a centralized common processor. Look at this as a hub and spokes. Each device, a spoke, communicated with the TechLink computer, the hub. The Tech Link computer took every request and directed to the correct spoke. A simple architecture, but one that doesn't scale, requires too much wire, and is totally reliant on the hub.

Today's Tech Link is a distributed architecture, much like the internet. Each device now has intelligence. They know how to listen and reject any message not addressed to them. This allows the devices to share the interconnecting wires or airwaves. The interconnecting systems (wires or radio signals) run at a high enough speed to support all devices. It's more reliable and can support more devices. It's also more sophisticated requiring specialized equipment to troubleshoot. Given it's intelligence, most have very good built-in diagnostics and some level of self healing.

I know some like to bad mouth advancements in technology, well at least until they own a bus with those advancements or until they wake up one day and finally realize there coach and previous coaches had multiplexed system and they didn't even know it.

Thanks to ARPAnet, the precursor to the INTERNET, and our desire to do everything wirelessly, we can expect more and more systems to move to the "multiplexed" world.

[Parkers]

I'm in. I attended the MiniRally last year and it was excellent.