Download Configuring the 3512

Timing
Default:
Network
Options:
Network, Internal, Ext. P1 through Pn (n=number of DTE ports in unit)
Description:
This parameter selects the 3512’s primary-line transmit timing source.
(The 3512 always derives its receive timing from the received data signal).
Network: With this option, timing is derived from the received data signal.
This is also known as loopback or receive timing. Use this option when
operating over a digital transmission services (DDS) network.
Internal: This option uses an internal oscillator for timing. Use this option
at one end of back-to-back 3512 applications, such as limited distance
drivers and pre-installation setup.
Ext P1 through Pn (where n=a DTE port number): With these options, the
3512’s timing is derived from the specified port’s DTE clock.
NOTES:
1) Ext Pn is not recommended for DDS networks. Motorola recommends
using Network timing.
2) With Ext Pn, set the corresponding Pn Data parameter (MODIFY
PORT category) to either Sync Ext or Sync Sta.
IMPORTANT: External timing only operates when the line rate is an exact
multiple of the port rate supplying the timing. This precludes the use of
external timing when the Opmode=DDS-II, because the actual line rates are
never exact multiples of port rates. For the same reason, external timing is
not supported when Opmode=DDS-I, and DTE Con=a bitstealing option.
Refer to Chapter 6 for tail circuit application timing considerations.
4-14 Configuring the 3512