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Forum LockedSending NUL control char from keyboard

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anonymous View Drop Down
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    Posted: January 16 2005 at 5:58am
I have one of my function keys for a client system set to a plain '^' with a label of "Break". Since I don't use a "set-break .00" in D3 myself I haven't used this for a long time and now I'm not sure if it ever worked. Since so many people use .00 as their break, is there any way for AT to send that break sequence? Is there a defined way to send any ^nnn sequence outside of using, for example ^g for a hex x07?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PSchellenbach Quote  Post ReplyReply Direct Link To This Post Posted: January 16 2005 at 6:13am
The most appropriate keyboard sequence to send an ASCII NUL character would be Ctrl+@, which would be Ctrl+Shift+2 on a normal US PC keyboard. Other language keyboards likely would have the "@" symbol on different keys. The control character keyboard logic in AccuTerm relies on the Ctrl key pressed along with an alpha key, which are always key codes 65 to 90 (A-A), regardless of the Shift key state. For characters 27 to 31, Windows appropriately decodes the Ctrl+[ , Ctrl+] , Ctrl+^ and Ctrl+_ keys. But for Ctrl+@, Windows does not generate any key code. And since the "@" key is not in the range of 65 to 90 (A-Z), AccuTerm does not recognize it directly as a control key. The only alternatives are either modifying AccuTero to use something like Ctrl+Space for the NUL character or to manually program a function key to send the NUL character. I am reluctant to make Ctrl+Space send NUL as a general AccuTerm behavior because I think this might cause inadvertent NULs to be entered in some unsophisticated input routines. So that leaves the choice of manually programming a function or editing key with "^@". One could also program the actual combination of Ctrl+Shift+2 to send a NUL by editing the session configuration file (using Notepad, Wordpad, etc) and adding the setting:
      
     [Keyboard]
     3050="^@"

The value 3050 is derived by adding the key number for the "2" key, which is 50, to a modifier representing the state of the Ctrl, Shift and Alt keys, which is 3000 for Ctrl and Shift.

Thanks,

Pete
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