CTI Products NCB/EM with External PSTN Modem - Manual (Page 56)

CTI Products, Inc. NCB-EM User Guide
Appendix G. Modem Notes 50
Leased-Line Mode
Leased-Line mode is the simplest operational mode of the NCB module. After power-up or reset, an NCB
module set to ‘Leased-Line: Originate’ mode will immediately go offhook and emit a cyclic calling tone to the
telephone circuit. An NCB module set to ‘Leased-Line: Answer’ mode will go offhook and wait for detection
of the calling tone from the distant end. When this calling tone is detected, the modem training sequence
begins. This training sequence determines telephone circuit characteristics, sets appropriately equalization
parameters and other housekeeping items, and concludes with the "CD" (carrier detect) LED illuminating.
Within 2 seconds after this LED lights, data packets can flow across the modem connection and the
simultaneous voice/data facility is enabled to the “AUDIO” connector.
The elapsed time between training sequence start and end (carrier detect) is tracked by a timer inside each NCB
unit. If the time reaches 20 seconds and training has not concluded, the NCB units will automatically restart the
calling tone sequence. Once a connection is established between the two NCB modems, any loss of carrier will
be detected by both NCB modules and cause them to automatically restart the calling tone sequence. Data
entering the NCB module while the modem is in the calling tone or training sequence is not buffered.
Initialization of MultiTech Modem Model MT2834L
This external leased-line/dial-up modem must be configured before use with the NCB module. Configuration
parameters are stored in the non-volatile memory of the modem and, therefore, only needs to be performed
when first installing (or replacing) the modem. Use the following steps to configure this modem model:
a) Set the DIP switches on the side of the modem as follows:
1: DOWN 5: # 9: DOWN 13: UP
2: UP 6: UP 10: UP 14: UP
3: * 7: DOWN 11: DOWN 15: UP
4: UP 8: DOWN 12: DOWN 16: UP for 2-Wire, or
DOWN for 4-Wire
* Set DOWN normally, UP to connect modems back-to-back with a short cable.
# For a single dedicated phone line, one modem must have switch 5 DOWN, the other modem
must have switch 5 UP.
b) Set NCB module switches as follows:
MODE 1: C BAUD 1: 7 BAUD 2: 0 OPTION B, 1 & 2: UP
c) Connect the modem to the NCB “PORT 1” connector.
d) Power up the NCB unit and the modem (any order).
e) Wait for the “ERR” LED on the front of the NCB unit to stop flashing. When it does, power down the
NCB unit and the modem.
f) Change DIP switch 10 on the modem to DOWN.
g) Reconnect the modem to the desired NCB “PORT 1” (if different from the NCB used for
configuration) and change “MODE 1” to the “D” position.
h) Re-power the NCB unit and modem.