6100 ADCCP Programming Manual

(68) MODEM CONTROL
Requests and Responses
069225 Tandem Computers Incorporated 6–31
(68) MODEM
CONTROL
The MODEM CONTROL request and response are used to connect or disconnect
modems for switched lines, and in error recovery for leased lines.
Request The MODEM CONTROL request connects or disconnects the modem by setting or
resetting the DTR modem signal. For switched links, the request completes only when
DSR appears.
You must use the MODEM CONTROL request to establish a switched connection.
This request can also be used in error recovery. When the MODEM CONTROL
request is used for error recovery, the line can be either leased or switched.
The request buffer format is:
Function := 68
Modifier := 1 to connect the modem by setting DTR
2 to disconnect the modem by resetting DTR
Request ID := A unique value from 1 through 32767,
determined by the application.
Text Out := 0
Text In := 0
Text None
Response The MODEM CONTROL response is the expected answer to the MODEM CONTROL
request. It indicates whether the exchange of DTR and DSR signals succeeded.
For a list of the status codes and their definitions, see “Status Code Definitions” at the
end of this section.
The response buffer format is:
Response := 68
Status := 0 if the request was successful, or an
error code if the request was unsuccessful.
Request ID := The same as in the request
Text Out := 0
Text In := 0
Text None