AT&T 7400B Plus User Manual page 146

APPENDIX A: AT COMMAND SET
Page A-15
Command:
Function:
Type:
Arguments:
S-Register:
Example:
Comments:
See Also:
&C
Data Carrier Detect (DCD) options.
configuration
The &C command accepts one of two arguments as follows:
0 - (or no argument) maintain the DCD circuit on at all times
(factory-default setting)
1 - the DCD circuit operates according to the EIA-232-D
standard
Bit 5 of S21 is set according to the argument used with the &C
command.
at&c1 ( )
Enter
In the example, the DCD circuit operates according to the EIA-
232-D standard. This would be an appropriate setting for when
the 7400B Plus is used at a remote site.
Regardless of which option is currently in effect, the DCD circuit
of the 7400B Plus is always off during self-test.
Chapter 3, "Configuration and Operation"; Appendix C, "S-
Registers."
DEFINITY Communications System
7400B Plus Data Module
User´s Guide