“Perpetual” Dial-Up Modem Connection
with the NCB-International
NCB-EM Technical Note
TN 013
The NCB-International Network Combiner Module can be configured to provide a “perpetual” modem
connection using dial-up service, with no runtime user or application intervention required. This provides
the advantages of lease-line operation without the added cost of actual leased-lines. Operationally, the
external modem of the NCB-International unit used in originate mode is configured with the telephone
number of the NCB-International unit used in answer mode. When powered on, the originate mode unit
automatically dials the answer mode unit and the connection occurs without user or application
intervention. Should the link between the two modems be broken for whatever reason, the originate mode
unit will automatically redial the answer mode unit and re-establish the connection.
This functionality requires the firmware in the NCB unit to be 1.80 or higher.
The following provides the steps for configuring the NCB-International units (both the NCB module and
the external Multitech modems) for this functionality.
Identify “NCB Unit 1” as the NCB unit/modem combination to be used in originate mode and “NCB Unit
2” as the NCB unit/modem combination to be used in answer mode.
• Set the switches on both NCB units as follows:
BAUD 1 : 7
BAUD 2 : 0
MODE 1 : C
MODE 2 : C
OPTION B positions 1 through 4 UP
OPTION A positions 1 through 5 and 7 through 8 : UP
OPTION A position 6 : DOWN on NCB Unit 1 and UP on NCB Unit 2
• If you are using the leased-line modems (MT2834BL) in dial-up mode, set the DIP switches on the side
of those modems as follows:
1: UP
5: UP
9: DOWN
13: UP
2: UP
6: UP
10: UP
14: UP
3: UP
7: DOWN
11: DOWN
15: UP
4: UP
8: DOWN
12: DOWN
16: UP
• Connect the DB25 connector on each modem to the “PORT 1” connector on the rear of the
corresponding NCB unit using the cables supplied with the modem or the NCB.
• Connect power to the modems (and switch them on), and to the NCB units via the front panel “DC IN”
connector. The units can be powered-up in any sequence. Both NCB Unit “ERR” LEDs will begin to
flash.
NOTE: It is normal for the NCB Unit ERR LED to flash quickly for up to 30 seconds
after power-up or reset of a fully configured and connected NCB-International module.
This indicates that any external modems configured for use are in process of initializing.
A problem is indicated only if the ERR LED locks on or continues to flash for more than
30 seconds after power-up or reset.
• After the ERR LED stops flashing on NCB Unit 1 (the originate mode combination), perform the
following steps on it:
•
Disconnect the power cable from NCB Unit 1.
•
Disconnect the modem cable from PORT 1 of NCB Unit 1.
April 28, 2000
CTI Products, Inc.
Phone: +1.513.595.5900
Fax:
+1.513.595.5983
1211 W. Sharon Road, Cincinnati, OH 45240
Email: info@ctiproducts.com
Web:
www.ctiproducts.com
Technical Note
TN 013
•
Change the MODE 1 switch on NCB Unit 1 only to D.
•
Change OPTION B switch on NCB Unit 1 only, positions 1 & 3 to DOWN
•
Connect the modem cable to a PC running a terminal emulation program (such as HyperTerminal
provided with Windows 95). Configure the terminal emulator for 57600 baud, no parity, 8 data
bits, 1 stop bit (N-8-1).
•
Enter +++AT <cr> on the PC (<cr> indicates pressing the Enter key). You should get the
response: OK from the modem.
•
Enter AT$D1&W <cr> on the PC. Again, you should get the response: OK from the modem.
•
Enter ATDTnnnnnnnN0 <cr> on the PC where nnnnnnn is the complete telephone number of
NCB Unit 2 (the answer mode unit), including any outside line access code, long distance
indicator and area code of the number. Again, you should get the response: OK from the modem.
•
Disconnect the modem cable from the PC and reconnect it to PORT 1 of NCB Unit 1.
•
Connect the modems of both NCB Unit 1 and NCB Unit 2 to their respective telephone lines.
•
Reconnect the power cable to NCB Unit 1.
•
Within 10 seconds, NCB Unit 1 should initiate a call to NCB Unit 2. NCB Unit 2 will
automatically answer the incoming call and the connection will be established. On some
international modems with “blacklisting” features, this first initiation of a call could take up to 70
seconds.
•
The modules are now ready for use. Any LonTalk packets entering one NCB unit will exit the
other and vice-versa. Breaking then restoring the telephone line connection between the modems
will cause the connection to drop and then automatically re-establish. Connection status and speed
can be queried by using the NCBCON software, as described in the section of the NCBInternational quickstart guide titled “NCBCON Software Installation and Use”.
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April 28, 2000