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VulcanSphere (talk | contribs) Adding local short description: "Control signal", overriding Wikidata description "control signal in RS-232 serial communications" (Shortdesc helper) |
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==Signaling for modems==
{{further|Command mode and Data mode#Switching between modes}}
The DTR signal is an important call control signal for a data modem. According to the RS232 standard, dropping DTR from active to inactive for at least two seconds tells the modem to disconnect (end) a call or data connection.
When a modem is being used for automatic answering (such as with the command ATS0=1), the DTR signal confirms to the modem that the computer is available to accept a call.<ref name="V250_6_2_9" >{{Citation |title=V.250 : Serial asynchronous automatic dialling and control (05/99, 07/03) |chapter=6.2.9 Circuit 108 (data terminal ready) behaviour |publisher=[[ITU-T]]/Telecommunication Standardization Bureau |url=http://www.itu.int/rec/T-REC-V.250/en |format=PDF}}</ref>
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