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 COM_SKEY()
 Monitors the port using key traps during background transmission
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 Syntax

     COM_SKEY([<nComPort>],[<nKeyValue1|cKeyValue1>],
        [<nKeyValue2|cKeyValue2>]) --> lActive

 Arguments

     <nComPort>  Designates the port (1 to 4) that is monitored in the
     background during transmission.

     <nKeyValue1|cKeyValue1>  Designates the key code placed in the
     keyboard buffer as soon as the port send buffer has been cleared.  Like
     the values available in CA-Clipper's SET KEY TO command, the key value
     can be a numeric value or an individual character.  When this parameter
     is not passed, the supervision of buffer overflow can be switched off.

     <nKeyValue2|cKeyValue2>  Designates the key code that the function
     places in the keyboard buffer at the start of a software or hardware
     handshake.  Like the values in CA-Clipper's SET KEY TO command, the key
     value can be a numeric value or an individual character.  When this
     parameter is not passed, the supervision of buffer overflow can be
     switched off.

 Returns

     COM_SKEY() returns .T. when the selected character is placed in the
     keyboard buffer by the corresponding event.

 Description

     This function allows you to monitor a transmission in the background
     with regard to the hardware or software handshake and the contents of
     the buffers.  If you have designated <nKeyValue1>, it is deposited in
     the keyboard buffer as soon as the sending buffer is empty.

     If the software or hardware handshake has been implemented by COM_SOFT()
     or COM_HARD(), then the COM interface program places <nKeyValue2> in the
     keyboard buffer when an XOFF is encountered or the CTS input is
     deactivated.  If you have passed <nKeyValue1>, it is deposited in the
     keyboard buffer as soon as the sending buffer is empty.

     Both events can prove very effective when combined with a CA-Clipper key
     trap.  In this way the program does not constantly have to review the
     status of the sending buffer; it simply "takes note" when something
     happens.  The specific event is then determined with COM_SMODE() within
     the called procedure.

 Note

     Important!  After each execution of a trap, COM_SKEY() must be
     reactivated.

 Examples

     .  Determine if the port 2 buffer is empty:

        COM_SKEY(2, , 225)            // Place code 225

     .  Monitor the software and hardware handshakes for port 2:

     SET KEY 225 TO HANDSHAKE
        ? COM_SKEY(2, , 225)          // OK when returns .T.

        COM_SOFT(2, .T.)              // Software handshake on
        COM_HARD(2, .T.)              // Hardware handshake on

        COM_SEND(2, LongText)         // Transmit something...

     .  It is important that you always send the parameter:

        PROCEDURE HANDSHAKE(A, B, C)

           * Your Program

           COM_SKEY(2, 225)           // Must be reactivated
           RETURN