Does a Diseqc switch have a default condition?

[Thala Dan]

How does a diseqc switch behave if connected to a non-diseqc decoder?
Does it default to a particular LNB input (for example, LNB1), or does it just look like a brick wall in the absence of instructions from the decoder?

[beer4life]

How does a diseqc switch behave if connected to a non-diseqc decoder?
Does it default to a particular LNB input (for example, LNB1), or does it just look like a brick wall in the absence of instructions from the decoder?

It would depend on the type and configuration.
But why would you want to do that?
Since they only change state with a Signal, I would surmise they would remain in last valid state.

Here's a selection;

[tristen]

It would depend on the type and configuration.
But why would you want to do that?
Since they only change state with a Signal, I would surmise they would remain in last valid state.

Yes. Both theory and experience lead me to agree with that.

Here's a selection;

Good link, Beer4life! It illustrates your point extremely well.

[Thala Dan]

Good link, Beer4life! It illustrates your point extremely well.

Actually, I'm not quite sure what his point was.

The question was pretty straightforward - "How does A diseqc switch behave if connected to A non-diseqc decoder?

Why would I want to do that?

Because I am contemplating connecting a DSD4121 to an existing dual-LNB dish installation which includes a 4-way diseqc switch. That is, in place of the existing Strong decoder, not in addition to it, to save any further confusion.

The purpose of my question was to determine whether the diseqc switch would represent an impassable barrier to the 4121, or whether, in the absence of any diseqc instructions from the decoder, it would simply default to one of its inputs, such as LNB1.
If the latter were the case, then I could simply ensure that the C1/D3 LNB was connected to the "default" input.
If that was not the case, and the diseqc switch refused to play ball in the absence of a diseqc instruction, then I'll have to think of something else.

Thanks, anyway.

[tristen]

Unless I miss the point, Beer4life's "point" in posting that link, was to illustrate, in a "not-too-subtle" manner, that there are many different DiSEqC switches in use today.

Well, what does that mean in practice?

Let me elaborate ...

DiSEqC switches have been in use now for many years and, as a consequence, there are many different models made by many different manufacturers.
Although "in principle" they are all DiSEqC switches, the "internal electronic design" will undoubtedly vary from one model to another as well as from one manufacturer to another. This results essentially from many different design engineers being involved over time and the availability, also over time, of suitable electronic componentry.
This "natural" variation means that it is literally impossible to predict what the behaviour of any particular DiSEqC switch will be in the absence of the relevant control signal, i.e. some might do this and some might do something else entirely different. In other words, put quite simply, it is impossible to predict, given the variability involved!

Now that you have "fleshed out" your purpose for asking the original question, it is possible to offer some additional advice, which I hope you will find helpful.

In your particular situation, as the UEC DSD4121 receiver appears to lack DiSEqC capability, the best course of action is to remove the existing DiSEqC switch and replace it with a "F" coupler, thus connecting the relevant LNB directly to the DSD4120 satellite receiver.
Yes, you might be lucky enough to receive a signal by leaving things as they are, but there is no way to ensure that the DiSEqC switch will remain in that particular position over time.

By eliminating the switch, you will ensure the ongoing integrity of the connection.

Do the job properly now, rather than having to do so in the middle of watching your favorite television program, on a dark, stormy night!

[beer4life]

Sorry guys, I thought that this genie had been laid to rest.

There are many variants of DiSEqC switches.
Many Manufacturers had there own.
Eutelsat standardised and patented these with backward compatibility where possible.

Some debate and confusion here:

It's a real can of worms, believe you, me.
All these Switches effectively come under the DisEqC Protocol Umbrella.

[Thala Dan]

Thank you Tristen, for a comprehensive and elegant answer to a simple technical question.

I was a aware of the existence of numerous brands and configurations of diseqc switch (I own several different types myself), but I confess that I had assumed that a protocol was a protocol, and that all diseqc switches would be created equal.
Apparently this may not be the case.

There are several alternative options available to me, one of which you suggested.
Most likely I will bite the bullet and replace the C1/D3 LNB with a dual output LNB, and run a second cable for the UEC – leaving the existing diseqc arrangement in place.

It was whilst I was considering these options that the question arose in my mind as to how the diseqc protocol and hardware handled the no-diseqc decoder situation.
My original question was an attempt to explore that technical aspect, rather than get bogged down in the detail of what I was trying to do and why.

I take on board what you have said, and appreciate it….however….curiosity being what it is, I will probably try out the UEC box on a couple of different diseqc switches…just for the hell of it

Many thanks again.

[tristen]

….however….curiosity being what it is, I will probably try out the UEC box on a couple of different diseqc switches…just for the hell of it ....

This is O.K. for curiousity sake, but don't ignore my comment in regard to assuming that a DiSEqC switch will continue to remain in a particular state without the continuous application of the appropriate switching signal, simply because you are lucky enough to discover that it does at present.

[Thala Dan]

This is O.K. for curiousity sake, but don't ignore my comment in regard to assuming that a DiSEqC switch will continue to remain in a particular state without the continuous application of the appropriate switching signal, simply because you are lucky enough to discover that it does at present.

Thanks for the concern, Tristen

Fortunately both the dish and the diseqc switch are right outside my caravan window at about shoulder height - so I don't envisage any major midnight sorties if it all goes pear-shape

Cheers