CTI Products EXB-232 Asynchronous Serial System Extender - Manual (Page 17)

68-11089-115
13
3.3 Controls
3.3.1 EXB-TELCO Controls
The 8 position DIP switch labeled "OPTION A" provides for EXB module static configuration.
Section 2.1 of this manual lists the function of each switch position. This section details how to
set the switches for each type of intended use. The OPTION A switch is read by the internal
EXB circuits at module power up or after pressing the RESET pushbutton on the EXB module
front panel.
OPTION A switch positions 1 and 2 control the connection operation of the EXB module
modem. Use the following table to select the proper settings of these two switch positions:
Operational Mode Switch Settings
Leased-Line (Answer) 1 up, 2 dn
Leased-Line (Originate) 1 dn, 2 dn
In order for two EXB modules to communicate via the telephone circuit, one must be set to
ORIGINATE mode and the other to ANSWER mode. It does not matter which EXB module is
in which mode, only that one is Leased-Line (Originate) and the other Leased-Line (Answer).
OPTION A switch position 5 should be set Up for normal systems.
For Custom Engineered Systems, set as indicated in Custom Documentation
OPTION A switch position 6 should be set to match OPTION A switch position 1.
OPTION A switch position 7 is used to set the transmit level from the modem. It should be
normally left in the UP position for telephone lines. If two EXB units are to be connected “back-
to-back” in leased line mode (with only a short cable between the “LINE” connector on each
unit, in lab test situations, for instance) or are connected standard Starplex multiplex equipment,
switch position 7 must be set to the DOWN position in order for the two modems to connect
properly.
OPTION A switch position 8 controls the selection of 2 wire or 4 wire mode for leased-line
operation.