Table of Contents
Advertisement
MT56DSU2 Owner's Manual
3.2.4 Elastic Store
This function allows the MultiDSU56K to compensate for small timing phase "drifts" that occur in
applications using analog modems for off-net (non-DDS) extensions. An analog off-net extension
application is described in Appendix A. This option should be enabled on all MultiDSU56Ks that are
connected to analog modems.
Notes for off-net (elastic store enabled) sites:
• a special DCE-DCE cross-over cable is required (not supplied by Multi-Tech).
• the modem located with the MultiDSU56K must be set for external timing. The modem located at the
far end of the off-net extension must be set for slave timing.
• With applications using controlled carrier, the CTS delay of the far-end modem of the off-net
extension must be set for a longer period than the MultiDSU56K's CTS delay time.
3.2.5 System Status
With this option enabled, the MultiDSU56K conditions the DSR signal with additional parameters to
provide added information to the connected DTE concerning the Ready status of the communications
channel.
Normally when this option is enabled, this signal is on when the MultiDSU56K is powered on and not in
test mode.
On most modems, the Data Set Ready (DSR) signal at the DIE interface is used to provide a basic
indication of the modem actually being ready to transfer data. The System Status option simply provides
a better means of informing the DIE of a ready condition.
The default for this function is System Status disabled, preventing the DIE from interpreting momentary
line interruptions as a communications channel failure. (Refer to Chapter 2 for changing the default DIP
switch settings.)
3.2.6 Circuit Assurance
This option, when enabled, causes the MultiDSU56K to condition the CTS signal to inform the DIE of
the transmit ready status of the entire communications channel.
In most installations, the 015 signal at the DIE interface is the basic P15 signal delayed in time. Even
though this could imply that the communications channel is ready for data to be sent, it is not typically
conditioned by channel status to indicate an actual "ready" status.
With the Circuit Assurance function enabled, the MultiDSU56K does not turn the 015 signal on unless
both the CD is on and the RTS/CTS delay has timed out.
The default for this function is Circuit Assurance disabled. (Refer to Chapter 2 for changing the default
DIP switch settings.)
3.2.7 Clocking
This option allows selection of the MultiDSU56K's clocking (timing for synchronization) from one of
three sources. These clocking sources are discussed below.
Internal clocking enables the MultiDSU56K to accept timing from its internal timing oscillator.
External clocking allows the Mu1tiDSU56K to derive timing from any external device that can supply
timing to the External Transmit Clock line on the MultiDSU56K's DTE interface connector. This external
clock must be within 0.008% of the nominal data rate.
DDS timing allows the MultiDSU56K to accept timing signals from the DDS network's receive bipolar
signal. Use this selection whenever the MultiDSU56K is connected to the DDS network lines.
The default for this function is DDS Clocking enabled. (Refer to Chapter 2 for changing the default DIP
switch settings.)
82017502
16
Advertisement
Table of Contents
