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BI-39077 DATA LINK TO GTI UNITS
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• Set the modem to automatically answer incomming calls.
• Set the modem to not echo off line commands.
• Set the modem to supress the addition of /ARQ to the end of commands such as CONNECT9600,
CONNECT2400, etc. This addition will make the commands unrecognizable to the GTI unit.
3. Set the baud rate for the RS-232 port on the GTI unit using DIP switch SW2 sections 6, 7, and 8 located on the right
side of the GTI unit. To get to the DIP switch after the GTI unit has been mounted in an EDACS repeater cabinet,
remove four screws in front and two in back. Then slide the GTI unit forward just enough to reach the DIP switch. If
there is enough slack in the connecting cables, it isn’t necessary to disconnect them or power from the GTI unit. The
layout of the DIP switch sections is shown in Figure 25. The DIP switch settings for various baud rates are shown in
Table 4. The recommended baud rate is 9600 bps.
4. Turn on the external modem at the GTI unit end. Then press the RESET button on the GTI unit, to force it to read
the new DIP switch settings and issue "AT" commands to program the external modem. For this to work, the modem
must be powered up before you reset the GTI unit. After the GTI unit is on, it sends the AT command to the external
modem at the GTI unit end every few minutes and looks for the OK response (meaning the modem is ready and
listening).
5. Using the GTI Configurator, select (highlight) the System config operation from the Edit group in the Main Menu
screen, and press the Enter key to display the System Configuration screen. In the INDEX window, select (highlight)
the system for which you are setting up communications, and press the Enter key to move to the SYSTEM CONFIG
window for that system. Select (highlight) the System Access field, type "X" (for external modem), and press the
Enter key to display the EXT_MODEM pop-up window (just below the System Access field). The EXT_MODEM
pop-up window contains a Phone # field and a Baud Rate field. Type the telephone number (of the line connected to
the external modem at the GTI unit end) into the Phone # field, and press the Enter key to move on to the Baud Rate
field. If the number shown in the Baud Rate field is the rate you want, press the Down Arrow key. If the number
shown in the Baud Rate field is not the rate you want, press the Enter key to display a second pop-up window (to the
right of the first) giving you a selection of baud rates. Select (highlight) the rate you want and press the Enter key to
move on to the PC Comm Port field back in the SYSTEM CONFIG window. Type in the number of the serial COM
port you will use, and press the Enter key. The System Configuration screen, showing the EXT_MODEM pop-up
window and the second pop-up window, is shown in Figure 31.
6. Turn on the modem at the GTI Configurator end.
7. Select (highlight) the Monitor operation from the Comm group in the Main Menu screen and press the Enter key. A
new screen then replaces the Main Menu screen. Select (highlight) the desired system from the INDEX window in
this new screen and press the Enter key. The INDEX window then disappears and a STATUS window appears
giving you the ongoing status as the System Configurator attempts to establish contact with the GTI unit through the
local RS-232 connection you have just made. Initially this STATUS window will show the following two statements:
“Connecting to system....” and “Requesting unit type...”. If the GTI Configurator does not receive a response from
the GTI unit, the STATUS window will show the following additional statement: “ERROR: No response, resending
pkt.”. Each time the GTI Configurator tries and fails to establish contact, the STATUS window will show the
following additional statement: “ERROR: No response, resending pkt.”. If the GTI Configurator fails to establish
contact with the system after three attempts, the STATUS window will show the following additional statements:
“ERROR: Exceeded packet retries”, “Unit never detected”, “Logically Disconnected”, and (after a pause) “Fully
Disconnected”. If the GTI Configurator establishes contact with the system, it will briefly (if you blink you will miss
it) show the following two additional statements: “CONNECTED!” and “Ready to process commands”, and then
display the Interconnect Monitor screen. A sample Interconnect Monitor screen is shown in Figure 27.