GBox in a two-motor one-receiver system?

[GrumpyGuy]

Has anyone tried using a V3000 (or any other GBox) in a 2-motor setup?

The goal is one receiver driving a small dish mounted on a SG2100, AND a BUD by way of a GBox V3000.

What sort of switching arraignment are you using? I have heard it said that 22kHz switches typically can handle more pass through current than DiSEqC can, but I've never seen much in the way of documented specifications for either variety of switches.

 

[Anole]

Here's what I said to Kira in the other thread:

Ecoda 22khz 2-input switches are much more robust, and if I had to run a motor on a switch, it'd be that one.

We need more discussion, ideas, and testing, but let me propose a thought:
Take a look at the picture in this post in the Switches Simplified FAQ thread.
How about putting your USALS motor between the right diseqc switch output and the 22k ON input...
... then locate the Gbox between the left diseqc switch output, and the 22k OFF input?
How would that work for you (and others)?

I tried setting up both of the motorized dishes using the 22Khz switch as Anole suggested.
It didn't work like I wanted.
My Gbox kept moving the big dish even when I wanted to just move the little dish.

Below is a marked up picture showing that idea.
Perhaps someone will offer a thought as to why it (apparently) doesn't work properly.

I expected two entries on the receiver if you want both C and Ku bands on any given satellite.
The C-band entry has 22khz off, but the Ku-entry has 22khz on...
... am I missing something, here?

 

[Anole]

specs on Ecoda 22khz switch:

Product Specs
Input Frequency: 900~2400 MHz
Insertion Loss: 1.5 dB
Protocols: 1.0, 1.2, 1.3, 1.6, 2.0
Isolation: 20 dB
Passing Current: 300 Ma max. . . . <---- this spec bothers me
Control Signal: 0 / 22 Khz
Operating Temperature: 0 Deg C ~ 60 Deg C
Dimension: 62 (L) x 55 (W) x 21 (H) mm
Packed Weight: 4 oz

 

[Machman]

Perhaps someone will offer a thought as to why it (apparently) doesn't work properly.

I don't know about the Ecoda, but I know that some 22kHz switches pass power to both inputs at the same time, regardless of whether the tone is on or off. DiSEqC works by modulation of the LNB power, so you can expect both motors to move at the same time. Now, if you don't care about that, and you don't exceed the current limitations of the switch or receiver, then I guess you can say that it "works properly".

The 300mA limitation of the Ecoda could be a problem, assuming it isn't just a very conservative spec. The SG2100 is rated at 180mA operating current (and will obviously have higher start and stall current). That leaves you with 120mA for the LNBs on both dishes and the GBox, a limit that would almost certainly be exceeded. One solution is to modify the SG2100 with a separate power input, which is kind of nice to have anyway. In fact that would get two birds stoned at once: current would no longer be an issue, so you could use a DiSEqC instead (which would only power one motor at a time).

The other option is to just use the Ecoda and hope it doesn't burn out. I'd personally hate to ruin such a useful and venerated switch, but a new one is only five bucks after all

 

[GrumpyGuy]

I dug up the DiSEqC bus spec, and learned that DiSEqC data bit signaling uses 22kHz as a carrier freq, with maximum continuous pulse width of 1 ms.

Could it be that the 22kHz switch:

• switches only after seeing 22kHz for longer than 1ms?
• blocks only DC voltages from passing through its deselected port?
• passes 22kHz DiSEqC pulses through both ports at all times?

If the above is true, that might explain why the V3000 moves the BUD, even with 22kHz "OFF" in the receiver's satellite setup menu. The V3000 has its own power supply, it would not care that the switch has blocked DC from the receiver.

If I had a 22kHz switch on hand I could just break out the scope and get the answer to those questions.

The switch data is a nice find, and yes, 300mA max. pass current would have me living on the edge. I have not taken real world measurements of the SG2100's current draw, but the specs claim 200mA "normal", and 350mA "max." I makes me sad when switches sacrifice themselves to save wear and tear on circuit breakers.

But a 0 deg. C minimum operating temperature? Guess that puppy wants to be an inside dog.

 

[Machman]

I starting to think that what allows the Ecoda to have DiSEqC switches cascaded behind it is that it intentionally passes DC and 22kHz to both inputs. I had always assumed that it uses something more complex like storing DiSEqC messages and then forwarding them after the 0/22kHz port selection is made, but that would cost more to implement. One could then assume that no other brands of 22kHz switches power both inputs all the time, otherwise they would have the same capabilities as the Ecoda (unless it's because they block 22kHz pulses for some other reason, which I doubt). I could theorize all night, but it's time for some real-world tests, so...

I don't have a plain old 22kHz switch and I can't find my Ecoda, so I tested a Zinwell 4x4 multi-switch:

                 | Switch port voltage:
Receiver setting | 0kHz/V | 0kHz/H | 22kHz/V | 22kHz/H
0kHz/V           | 15.2   | 13.4   | 0.0     | 0.0
0kHz/H           | 21.6   | 13.4   | 0.0     | 0.0
22kHz/V          | 0.0    | 0.0    | 15.2    | 13.1
22kHz/H          | 0.0    | 0.0    | 21.5    | 13.1

So, only half of the inputs are powered at a time. I'd be willing to bet that all non-Ecoda 22kHz switches behave similarly.

If it switches to the 22kHz side instantly upon seeing a 22kHz tone, that would still allow 22kHz pulses to leak through the 22kHz side to a self-powered device like the GBox. The 0kHz side might be immune to that, but if not there's a complex workaround for that too which I'll only describe on request

I hope at least some of that was useful

 

[linuxman]

Has anyone tried using a V3000 (or any other GBox) in a 2-motor setup?

The goal is one receiver driving a small dish mounted on a SG2100, AND a BUD by way of a GBox V3000.

What sort of switching arraignment are you using? I have heard it said that 22kHz switches typically can handle more pass through current than DiSEqC can, but I've never seen much in the way of documented specifications for either variety of switches.

To answer your question above, it is possible to use a GBox/VBox in conjunction with an SG2100 at the same time.

I asked the very same question over 2 years ago, and one of our members here named bidaw was doing it.

I don't know exactly how the wiring was done, but the GBox will ignore USALS commands and pass them down the cable to the SG2100.

You will not be able to use diseqc 1.2 on any satellite on the sg2100, but it will work.

If bidaw sees this, I am sure he will jump in with the wiring layout.

Or you can PM him and point him to the thread.

 

[Lak7]

With the warm weather this weekend, I was experimenting with a SG2100 in line with VBox.
But one thing I wanted to know was...
1) Will the VBox pass DiSEqC 1.2 and USALS when powered off, sill plugged in though?
2) Will the VBox ignore USALS commands when powered on?

For me, both were "Yes"

I did not try to use the VBox with the SG2100 attached due to a lack of an Ecoda 22KHz switch handy.
I was thinking....
Receiver------------>VBox-------------->22KHzOff------>DiSEqC1--------->BUD C Band
.............................................................\.....................\--DiSEqC2--------->BUD Ku Band
.............................................................>\
...............................................................>\--22KHzOn------>SG2100 USALS--------->Ku Band

 

[GrumpyGuy]

I asked the very same question over 2 years ago, and one of our members here named bidaw was doing it.

I don't know exactly how the wiring was done, but the GBox will ignore USALS commands and pass them down the cable to the SG2100.

You will not be able to use diseqc 1.2 on any satellite on the sg2100, but it will work.

Limiting my search to threads with posts by bidaw helped quite a bit. I'll be thrilled if his simple solution works for me too - receiver > vbox > sg2100 > 4 port disq

bidaw's November 2005 two motor install

bidaw's two motor install still working as of July 2007

Looks like all I really need to add to my system is the V3000, everything else is already in place.

 

[GrumpyGuy]

I starting to think that what allows the Ecoda to have DiSEqC switches cascaded behind it is that it intentionally passes DC and 22kHz to both inputs. I had always assumed that it uses something more complex like storing DiSEqC messages and then forwarding them after the 0/22kHz port selection is made, but that would cost more to implement.

I've been pondering some of the same things, and found answers in Eutelsat's DiSEcQ Bus Specification. Chapters 1 through 5 answered a lot of my questions - pfd of the spec attached

 

[linuxman]

Limiting my search to threads with posts by bidaw helped quite a bit. I'll be thrilled if his simple solution works for me too - receiver > vbox > sg2100 > 4 port disq

bidaw's November 2005 two motor install

bidaw's two motor install still working as of July 2007

Looks like all I really need to add to my system is the V3000, everything else is already in place.

I am glad you found the link.

I was pretty sure it was just that simple, but wasn't sure.