A400M on DAHDI User Manual
OpenVox Communication Co. LTD.
URL: www.openvox.cn
9
Chapter 2 Hardware Setup
There are some points that should be paid attention to when setting up
A400M.
2.1 Power supply
The board should be powered when any FXS module installed; please
connect the power source with A400M board by a 4-pin power source
connector. If all modules are red, it can be powered by MIMI PCI slot,
external voltage is unnecessary.
2.2 Timing cable
If you have just one card in the system, all channels on that card have
already run under the same clock source, so timing cable is unnecessary.
But if there are more than one card, using timing cable has some
advantages. Before using the clock line, each card works on its own
clock, therefore precision of the clock is limited; each card will send
/receive voice data at different speeds. In voice usage, this small issue can
be omitted, but in data communication such as Fax/Modem, it will cause
big problem. Data loss will cause communication broken or fax broken.
Timing cable will force all cards to work at the same clock source, send
data at the same speed, as a result no data will lost.
