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DEFINITY Communications System
APPENDIX A: AT COMMAND SET
7400B Data Module
User’s Guide
Page A-13
Command:
Function:
Type:
Arguments:
S-Register:
Example:
Comments:
at&d2
[ Enter ]
See Also:
&D
Data Terminal Ready (DTR) options.
configuration
The &D command accepts one of four arguments as follows:
0 - ignore the DTR interchange circuit (factory-default setting).
1 - return to the command state if an on-to-off transition is detected
on the DTR input; an active data call is not disconnected.
2 - go on hook when an on-to-off transition is detected on the DTR
input (EIA-232-D standard); an active data call is disconnected.
3 - perform a reset if an on-to-off transition is detected on the DTR
input; an active data call is disconnected.
Bits 3 and 4 of S21 are set according to the option used with the &D
command.
In the example, the DTR circuit is set according to the EIA-232-D
standard. This would be an appropriate setting for when the 7400B
Data Module is used at a remote site as a dedicated device to
automatically answer an incoming data call.
For the 0 option, the front panel DTR indicator (TR LED) is always on,
regardless of the state of the DTR input; for all other options the
indicator follows the state of the DTR input.
If the change of state for the DTR circuit persists for a time shorter
than specified in S25, the change is ignored.
Chapter 4, “Operation and Configuration”, Appendix B, “S-
Registers.”