3.1.1 Switch Set S1
The configuration switches on S1 set clocking, rate adaptation,
loopback enable, data invert, and interface (see also Switch S2). The
default settings are summarized in table below.
Switch S1-1: Terminal Interface (Works in Conjunction with
Switch S2)
Set Switch S1-1 (as well as S2-1 and S2-2)to determine whether
the signals passed between the Model 2703 and the terminal device
will follow the EIA-530 (RS-422), CCITT X.21 or CCITT V.35 standard.
If S2-1 and S2-2 are set for “EIA-530/X.21,” then the setting for S1-1
determines which of those two interfaces is selected. Note: If S2-1
and S2-2 are set for “V.35,” switch S1-1 must be set to “off.”
Regardless of the pin-out standard chosen, the physical connector is a
female UD-26.
S1-1
Setting
Off
V.35 Interface
On
X.21/EIA-530 (RS-422) Interface
S1-2 and S1-3:
Reserved for Future Use
5
S1 SUMMARY TABLE
Position
Function
Factory Default
S1-1
X.21/V.35
Off
V.35
S1-2
Reserved
Off
S1-3
Reserved
Off
S1-4
Rate Adaptation
Off
S1-5
Rate Adaptation
Off
S1-6
Data Inversion
Off
Not Inverted
S1-7
Clock Master/Slave
Off
Slave
S1-8
Test Enable
Off
Front Panel
}
2.048 Mbps
Switches S1-4 and S1-5: Rate Adaptation
Set Switches S1-4 and S1-5 together to allow the Model 2703 to
adapt to terminal devices that run at data rates less than 2.048 Mbps
(The network rate remains 2.048 Mbps regardless of the terminal rate
adaptation setting). The setting you select must match the data rate of
your terminal device.
S1-4
S1-5
Setting
Off
Off
2.048 Mbps
On
Off
1.024 Mbps*
Off On
512
kbps*
On
On
256 kbps*
Switch S1-6: Data Inversion
Set Switch S1-6 to determine whether or not the data stream from
the local DTE is inverted within the Model 2703 before being passed to
the G.703 network. You may need to invert the data stream when you
use the Model 2703 with an imbedded G.703 device that inverts the
data on the remote end. Normally, data inversion is not necessary.
S1-6
Setting
On
Data inverted
Off
Data not inverted
Switch S1-7: Master/Slave Clock
Set Switch S1-7 to allow the Model 2703 to provide the master
clock, or recover the clock from the G.703 network.
S1-7
Setting
On
Model 2703 is master
Off
Model 2703 is slave, (clock is recovered
from the network)
6
*NOTE: Revision C. Firmware (or newer, Implemented 6/19/98)
has been adopted to correct signal polarity at 1.024 Mbps, 512
kbps, and 256kbps. To operate Revision. C Firmware units with
Revision B. (or older) units at one of these sub-rates, you must
invert the data (Switch S1-6 On. See Below) (Firmware revision
level is printed on the label on the bottom of the unit).