7
8
S2-3: Extended Signaling Rate
The setting for switch S2-3 determines the range of variability the
Model 1140A “looks for” in asynchronous data rates (i.e., the actual
variance from a given frequency level the Model 1140A will tolerate).
S2-3
Setting
Off
-2.5% to +1% Basic
On
-2.5% to +2.3% Extended
S2-4 and S2-5: RTS/CTS Delay
The combined settings for switches S2-4 and S2-5 determine the
amount of delay between the time the Model 1140A “sees” RTS and
when it sends CTS. Options are no delay, 7 ms and 53 ms.
S2-4
S2-5
Setting
On
On
7 mS
Off
On
53 mS
On
Off
No delay
Off
Off
No delay
S2-8: V.54 Loopback Test Enable
To reset the V.54 circuit, set switch S2-6 to the “ON” position, then
back to the “OFF” position..
S2-8
Setting
Off
V.54 Enable
On
V.54 Disable
4.0 INSTALLATION
The Model 1140A is easy to install. After configuring the DIP
switches, simply connect the two fiber cables and then connect the
RS-232 interface. Figure 5 shows the location of the fiber connections
on the Model 1140A’s rear panel.
4.1 FIBER CONNECTIONS
The Model 1140A short range modems are designed to work in
pairs. You will need one at each end of a dual fiber cable. This cable
connects to each Model 1140A using either an ST or an SMA connec-
tor. Figure 6 shows a close up of each of these connector types.
4.2 RS-232 CONNECTION
The Model 1140A is designed to remain in DCE mode.
Figure 6. Close up of ST and SMA connections
Figure 5 Close up of ST and SMA connections
ST
SMA
Alignment pin
faces down
DIP Switches This Side
TX
RX
