0049-1800-xxx 326X V.34, V.34-SDC and V.32bis Series Modem – USER’S GUIDE 02/23/2010
Rev. A
Page 63
of
205
SDC Pre-Operation Notes
This section contains important information for using the 326X
FAST
-SDC Modem in SDC operating
mode.
Read this section before configuring the unit.
Operational Requirements
•
326X
FAST
-SDC modems require framed HDLC/SDLC-like data.
NOTE
: BER tests do not
operate in an SDC environment because the data is not framed.
•
326XFAST-SDC modems support an NRZ or NRZI data encoding method. Refer to the
DTE documentation for information on the data encoding method the DTE supports. (Refer
to Appendix A,
Data Form
[AT*DF] option, for details on NRZ/NRZI data encoding
methods.)
Optimizing Network Performance
The 326XFAST-SDC modem provides front panel displays of RX/TX Throughput and Link
Utilization. Higher values indicate more efficient utilization; lower values indicate less efficient
usage. These values are affected by the attached DTE and protocol characteristics – frame size,
window size, and DTE rate selected.
(Refer to Chapter 1 of the
326X Series Modem Reference Guide
for a description of how to use the
RX/TX Throughput and Link Utilization displays.)
Raymar-Telenetics recommends the following to maximize efficiency:
•
If your application is operating in a windowed protocol environment, set the window sizes to
greater than 1 to improve performance. Recall that windowing refers to the number of
packets sent before an acknowledgement is required.
•
To improve network performance, adjust frame sizes. The optimum frame size for most
applications is between 128 and 1024 bytes. Experiment with window and frame sizes for
maximum performance.
•
If link utilization is low, raise the DTE rate. Low link utilization typically implies that the
DTE equipment is the bottleneck in data transmission.
Configuring the Modem for SDC Operation
You can configure the 326X
FAST
-SDC Modem for SDC in one of these ways:
-
Select Option Set 2, 3, or 4 Leased, discussed below
-
Configure the modem as follows:
Select one of the reliable data transfer modes (Reliable, Auto Reliable, or Speed Auto
Reliable).
Choose an Auto-Call Unit (ACU) – AT, V.25bis, LPDA, or None – using the
ACU
Select
option, ACU OPTS category.
Select a bit-synchronous data format (depending on the ACU type).
Refer to Appendix A for additional information on each of these methods.
