US Robotics COURIER HST User'smanual page 35

COURIER HST
Terminal Rate
Select (&Bn)
&Bf!)
&81
Link Rate Select
(&Nn)
4-6
&Nf!)
&N1-6
Rate-Select
Guidelines
Use this command to select varying or fixed rates at the
terminal interface. Fixing a maximum rate at the terminal
interface offers greater efficiency, regardless of the modem
at the remote end of a connection.
Variable rate: the terminal interface rate follows the connec-
tion rate. Use this setting if your software switches its rate
when it receives the CONNECT result codes, e.g., CON-
NECT 2400, CONNECT 1200. The modem readjusts at the
next AT command or connection.
Fixed rate: allowable terminal/software settings are
l 9200/9600/2400/ 1200/300 bps. Setting the terminal to
19. 2k bps enables the greatest throughput.
~
See guideline
number 2 below.
If the &B and &N settings differ, be sure to use flow
control to prevent the possibility of data loss.
Normal operations: the link rate varies according to the
connection sequence.
Fixed link rate: the modem only connects if the remote
modem is also operating at the same rate. Allowable rates
are as follows:
&NI
&N2
&N3
300 bps
1200 bps
2400 bps
&N4
&NS
&N6
Reserved
Reserved
9600 bps
1. Some software doesn't support a fixed terminal rate, but
always switches bit rates to the link rate established by
the modems during their connect sequence. In this case.
leave the Courier set to &B0.
2. For maximum throughput, use the settings recommended
in Chapter 3 for both Originate and Answer Modes:
Terminal:
Modem:
19.2k bps
Fixed terminal interface rate (&BI)
Variable link rate (&N0)
Transmit Data flow control (&HI, 2, or 3)
3. You can filter out calls at other than a specific speed, for
security or other reasons, by fixing the link rate.
4. If the Courier HST is connected to a mainframe, the
mainframe may require that the terminal and link rates
be fixed with the &B and &N commands.