COMM query

[Adrian C Aitken]

Hi, does anyone know how to send 'Ctrl-Break' down a comms line (it's attached to a Cisco router and using HyperTerm, Ctrl-Break goes into maintenance mode).

Any help appreciated

Adrian Aitken

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[Tom Hanlin]

Ctrl-Break doesn't correspond to a standard ASCII or ANSI sequence, so you
would probably need specialized communications software or drivers.

Depending on your needs, you may be able to send Control-C or another
key combination instead.

Then again, there's a communications signal called BREAK which is not
related to Ctrl-Break (although it's conceivable that some comm software
interprets the Break key as a command to send a BREAK signal). BREAK is
a largely obsolete signal once used for purposes such as resetting a
communications session.

If this doesn't help, perhaps you could explain what you need in a little
more detail.

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Tom Hanlin
PowerBASIC Staff

[Adrian C Aitken]

Hi Tom,
The break signal *IS* this 'obsolete' signal !! Is it possible to send this via PB 6 ?

Adrian

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[Lance Edmonds]

According to my "Data and Fax Communications" bible, most _modems_ handle this with an AT command - "AT\Bn" (where n is in 100mSec units, from 1 to 9). There are S-register settings for handling the reception of a BREAK, etc.

However, at the UART level, a BREAK is controlled through bit 6 (BC - Break Control) of the Line Control Register.

It seems possible to use the EscapeCommFunction(hndl&,%SETBREAK|%CLRBREAK) or SetCommBreak(hndl&)|ClearComBreak(hndl&) to do this, but if you are using PB/DLL's serial communications COMM SET #hComm&, BREAK = 1

However, I've not tried this - BREAK may be read-only, in which case you'll have to use the afore-mentioned API functions.

Note that you can retrieve the Operating System handle to an open PB/DLL comm port with FILEATTR(hComm&,2) - you'll need this value to mix the API call with PB/DLL COMM code.

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Adrian C Aitken]

hi Lance, the COMM SET #hComm&, BREAK = 1 GPFed my Win98SE PC continually (having to reboot often!) with Invalid Page Fault in module <>.
The API call EscapeCommFunction(hndl&,%SETBREAK) worked but then stopped DDT COMM working so I had to shut the port and reopen it again.

Thanks for your help

Adrian Aitken

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[Lance Edmonds]

Adrian, I'll check with R&D on the COMM SET BREAK issue... you wouldn't have some sample code that shows up the GPF by any chance? (saves me writing a test app from scratch to test with )

I don't have a copy of WIN32.HLP with me right now (I'm not at the office), but if I recall correctly, if you use the EscapeCommFunction to use the SETBREAK condition, you have to follow it with a CLRBREAK too, with an appropriate delay between.

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Adrian C Aitken]

Lance , heres the first part of a function - hopefully it explains itself
You can comment out the StatusMsg (just displays message on label) and WaitforRouter (just sits there waiting for passed string to appear).

Regards

Adrian Aitken

CALLBACK FUNCTION btnRebuild() AS LONG

DIM ff AS LONG  , lngAPI AS LONG

       MSGBOX "Switch off the router for 5 seconds," + $CRLF + "and press 'OK' after you have" + $CRLF + "switched the router back on." , %MB_OK , "Important"

       ff = FREEFILE
       ON ERROR RESUME NEXT
       ERRCLEAR
       COMM OPEN "COM1" AS #ff
       IF ERR <> 0 THEN
          IF ERR=70 THEN
             MSGBOX "Please switch the router on" + $crlf + "and ensure the BLUE cable" + $crlf + "is attached to the router" + $crlf + "and your PC." , %MB_ICONEXCLAMATION , "Error"
             EXIT FUNCTION
          END IF
          MSGBOX "Error opening COM1. Please re-try" + $crlf + "Error Code is " + STR$(ERR) , %MB_ICONEXCLAMATION , "Error"
          EXIT FUNCTION
       END IF
       COMM SET #ff, BAUD     = 9600   ' 9600 baud
       COMM SET #ff, BYTE     = 8      ' 8 bits
       COMM SET #ff, PARITY   = %FALSE ' No parity
       COMM SET #ff, STOP     = 0      ' 1 stop bit
       COMM SET #ff, TXBUFFER = 2048   ' transmit buffer
       COMM SET #ff, RXBUFFER = 4096   ' receive buffer

       StatusMsg "Waiting for router..."
       WaitForRouter ff,"###",1
       StatusMsg "Sending Break command..."
       lngAPI= FILEATTR(ff,2)
       EscapeCommFunction lngAPI,%SETBREAK  'no GPF
'      COMM SET #ff,BREAK = 1          ' GPFed every time
'      MSGBOX "Do you get here?"       ' never popped up

       COMM CLOSE #ff                  ' needed because of API call
       StatusMsg "ReOpening Comm port"
       ff = FREEFILE
       ON ERROR RESUME NEXT
       ERRCLEAR
       COMM OPEN "COM1" AS #ff
       IF ERR <> 0 THEN
          IF ERR=70 THEN
             MSGBOX "Please switch the router on" + $crlf + "and ensure the BLUE cable" + $crlf + "is attached to the router" + $crlf + "and your PC." , %MB_ICONEXCLAMATION , "Error"
             EXIT FUNCTION
          END IF
          MSGBOX "Error opening COM1. Please re-try" + $crlf + "Error Code is " + STR$(ERR) , %MB_ICONEXCLAMATION , "Error"
          EXIT FUNCTION
       END IF
       COMM SET #ff, BAUD     = 9600   ' 9600 baud
       COMM SET #ff, BYTE     = 8      ' 8 bits
       COMM SET #ff, PARITY   = %FALSE ' No parity
       COMM SET #ff, STOP     = 0      ' 1 stop bit
       COMM SET #ff, TXBUFFER = 2048   ' transmit buffer
       COMM SET #ff, RXBUFFER = 4096   ' receive buffer

       WaitForRouter ff,"mon" ,0
       StatusMsg "Now resetting..."
        ...etc

END FUNCTION

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[Lance Edmonds]

Thanks!

BTW, does clearing the break allow PB's COMM to continue working again, as per my last message? It is crucial that the break is cleared otherwise nothing is able to be sent through the port again.

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Adrian C Aitken]

clearing the break - dunno, I could only borrwo a router for the weekend and since I've got something that works thats it until next weekend!
I'll try to write the escape part but I use PB at home and my test routers at work (with everyone using it to go on the internet so I wouldn't be popular trashing the configuration !!!!)

Regards

Adrian Aitken

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