[vdr] DiSEqC and uncommitted switches (how to)

[Ora Järvinen <vdr@oraweb.de>]

I didn't find anything on cascaded/uncommited DiSEqC switches here (nor
anywhere else for that matter), so I thought I'd share this with the coming
generations.. :-)

Sorry for the longish post, but I don't have a suitable place to put this
in, otherwise I'd just post a link.

If you need to switch more than 4 LNBs (or whatever signal sources), a
standard 4-in-1 DiSEqC switch obviously doesn't cut it. You can use either
an additional 12V relay (works fine with most STBs) but VDR doesn't provide
a 12V switching signal (it would be doable, of course, with some additional
H/W and S/W).

The alternative is to use an "uncommitted" DiSEqC switch (such as the Spaun
SUR 220 F, there are probably others) cascaded with a standard switch. This
is what I use. I currently have 5 LNBs but this setup would work for up to 8
LNBs (or even more if you use the SUR 420 F).

The hardware configuration looks like this (in my case): the DVB-S card is
connected to the output of the uncommitted switch (SUR 220 F). A generic 4/1
switch is connected to input 1 of the uncommitted switch and four of the
LNBs are connected to its inputs.

Currently, as I only have 5 LNBs, the fifth one is connected directly to
input 2 of the SUR 220 F. If you have more than 5, you obviously need
another generic 4/1 switch here too.

diseqc.conf then looks like this:

------------------ cut -------------------------
# Input 1 - Astra 1 19.2E - uncommited switch input 1

S19.2E  11700 V  9750  t v W15 [E0 10 39 F0] W125 [E0 10 38 F0] W15 t
S19.2E  99999 V 10600  t v W15 [E0 10 39 F0] W125 [E0 10 38 F0] W15 T
S19.2E  11700 H  9750  t V W15 [E0 10 39 F0] W125 [E0 10 38 F0] W15 t
S19.2E  99999 H 10600  t V W15 [E0 10 39 F0] W125 [E0 10 38 F0] W15 T

# Input 2 - Sirius 5.0E - uncommited switch input 1

S5E  11700 V  9750  t v W15 [E0 10 39 F0] W125 [E0 10 38 F4] W15 t
S5E  99999 V 10600  t v W15 [E0 10 39 F0] W125 [E0 10 38 F4] W15 T
S5E  11700 H  9750  t V W15 [E0 10 39 F0] W125 [E0 10 38 F4] W15 t
S5E  99999 H 10600  t V W15 [E0 10 39 F0] W125 [E0 10 38 F4] W15 T

# Input 3 - Astra 2 28.2E - uncommited switch input 1

S28.2E   11700 V  9750  t v W15 [E0 10 39 F0] W125 [E0 10 38 F8] W15 t
S28.2E   99999 V 10600  t v W15 [E0 10 39 F0] W125 [E0 10 38 F8] W15 T
S28.2E   11700 H  9750  t V W15 [E0 10 39 F0] W125 [E0 10 38 F8] W15 t
S28.2E   99999 H 10600  t V W15 [E0 10 39 F0] W125 [E0 10 38 F8] W15 T

# Input 4 Thor - uncommited switch input 1

S1W   11700 V  9750  t v W15 [E0 10 39 F0] W125 [E0 10 38 FC] W15 t
S1W   99999 V 10600  t v W15 [E0 10 39 F0] W125 [E0 10 38 FC] W15 T
S1W   11700 H  9750  t V W15 [E0 10 39 F0] W125 [E0 10 38 FC] W15 t
S1W   99999 H 10600  t V W15 [E0 10 39 F0] W125 [E0 10 38 FC] W15 T

#  Hotbird - connected directly to uncommited switch input 2

S13E  11700 V  9750  t v W15 [E0 10 39 F1] W15 t
S13E  99999 V 10600  t v W15 [E0 10 39 F1] W15 T
S13E  11700 H  9750  t V W15 [E0 10 39 F1] W15 t
S13E  99999 H 10600  t V W15 [E0 10 39 F1] W15 T
------------------ cut -------------------------

Note that as there is no switch behind input 2 of the uncommitted switch,
selecting Hotbird only need a command to switch the uncommitted switch to
input 2. For the others, it is first switched to input 1 and then a command
is sent to the 4/1 switch behind it. It obviously cannot receive the command
before the uncommitted switch has really executed the switch - I couldn't
find a specification for the delay required anywhere, but 125 ms seems to do
the trick. 15 ms is definitely too short - and the delay probably depends on
the specific switches used.




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