[asterisk-dev] Timing Cables

[Russ Meyerriecks]

On Mon, Jul 7, 2014 at 3:33 PM, George Karagheaur
<george.karagheaur at gmail.com> wrote:
> Dear all,
> I have 4 units E1 cards Digium TE820 (8 E1 ports per card) in one server,
> and i put timing port as:
>
> span => 1,1,0,ccs,hdb3,crc4
> span => 1,2,0,ccs,hdb3,crc4
> span => 1,3,0,ccs,hdb3,crc4
> ..
> span => 1,31,0,ccs,hdb3,crc4
> span => 1,32,0,ccs,hdb3,crc4

This configuration is incorrect. The first number is the span number,
the second is the timing priority. Any span that is intended to
recover timing from an external source should have a positive priority
here. You can read more about the system.conf.sample that is installed
to /etc/dahdi/system.conf when you "make samples". It is also
available in the dahdi-tools repository.
http://git.asterisk.org/gitweb/?p=dahdi/tools.git;a=blob_plain;f=system.conf.sample;hb=HEAD

>
> How should i connect timing cables?

Make sure you have a real need for timing cables. They add complexity
and are typically not needed. Otherwise just connect them as per the
manual instructions and add "timingcable=1" to the module parameters
for the wct4xxp driver.

> In the user manual it is writen that with Diferential Timing cable i can
> connect only 3 TE820 cards, but i have 4, what to do? How to configure it
> correctly?

4 will probably work if you use the differential timing cable. I
believe that limitation was due to the signal integrity of the older
style timing cable.

> Second question: do i understadn correctly, that if i connect cards 1-3 with
> a timing cable, card 1-3 will use span 1 as timing port for all 3 cards,
> right?

Yes, which ever span is properly recovering the timing should be the
timing master for all spans in the timing cable system.

-- 
Russ Meyerriecks
Digium, Inc. | Linux Kernel Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
direct: +1 256-428-6025
Check us out at: www.digium.com & www.asterisk.org