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DLM4000 User Guide
PN 161-09997-003A
Feb 2005
Appendix C
AADB (Auto Answer Dial-Back)
When Installed
The DLM4000-AA Dial-Up Modem is capable of dialing a stored telephone number when a logic high signal is sent to a
terminal block connection at the rear of the modem. The modem will keep dialing until one of the following occurs:
1. A connection is made.
2. The Logic Flag is cleared(returned to logic low).
3. A second Logic High is presented at the override terminal.
The Auto-Alarm dial out function will not interrupt a call in progress and will not dial out if data is sent to RS232 port.
To activate the dial-up feature when carrier is lost, a voltage of 12 VDC should be applied between G (ground) and L. A
12 VDC level applied to O will override the activated dial-up feature. The time for re-dial is factory adjusted to 50% of R8’s
value on the AADB daughter board. To change the length of time the unit takes to cycle power, open the case and adjust
R8.
Note:
Data-Linc Group recommends leaving R8 set at the 50% position.
Typical Connection Diagram
The following describes the function of the connection points on the screw terminal block.
G
Logic Signal Ground
L
Alarm Logic Signal (input)
O
Alarm Override Signal (input)
C
Carrier Detect Signal (out)
The common ground point for the system is terminal G. The L terminal is an input connection that accepts a +12 VDC input
to activate the timing circuit. The O terminal will stop the timing process when +12 VDC is applied to the input. The C
represents the detected carrier voltage level. The carrier output will be around –7 VDC when carrier is not present. This will
be +7 VDC when the carrier is established.
C O L
G
+ -
R8
+12
VDC
