Instruction manual

Communications Setup
46 025-9416
The commands in this string equate to the following:
AT Get modem’s attention
&M0 Error Control disabled
&K0 Data Compression disabled
&I0 RX Flow Control disable
&H0 TX Flow Control disable
&N2 Force modem to 1200 baud
Note: Do not assume that the computer’s modem responds to the above commands exactly
as described. Always check the modem manual for custom initialization commands
and their use.
The following steps will allow you to change the modem initialization string:
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1. Exit MCU to DOS. (Hit <Esc> repeatedly or select Other, Exit.)
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2. Change to the \MCU directory (if not already there), by typing at the DOS prompt:
CD C:\MCU\<my site name>
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3. At the DOS prompt type “EDIT modem.ini”.
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4. Enter the new initialization string to disable the features previously mentioned. Do
not insert spaces between commands; the string should be continuous.
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5. Save the file and then exit to DOS.
The next time the location is ZLINKed, the computer will look at the “modem.ini” file for the
appropriate modem commands.
Note: If you are unsure about modem initialization commands, contact Zetron Mobile and
Paging Systems technical support for assistance. Be sure to have your modem manual
handy for easy reference before calling.
Troubleshooting Checklist
To avoid potential serial port problems, check the following:
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Verify that the dial string to the terminal is correct.
• If dialing over an End-to-End (POTS) line, you should hear/see the following events at
the modem installed on the PC when the MCU is dialing the Model 640.
1. Dial tone, followed by a string of Touch Tone digits
2. One to three rings
3. Model 640 answers with prompt “At the tone, enter your pager number.”, followed
by a beep prompt.
4. The PC sends the console access number (usually 0555 or 555) by way of the
modem as a string of Touch Tone digits.
5. The Model 640 returns a solid modem tone followed shortly by the modem carrier
“hiss” as it attempts to establish a connection.