Functions and Directives Functions and Directives

Function Com_Open() Foundation

Opens a COM port.

Syntax
Com_Open( <nComPortNum> , ;
          <ignored>     , ;
          <ignored>     , ;
          <ignored>     , ;
          [<nOpenMode>]   ;  // Default: 0
        ) --> lIsOpen
Return

Com_Open() returns .T. if the specified COM port was opened successfully or .F. otherwise.

Description

Opens specified COM port.

NOTE:

Parameters 2, 3 and 4 which are used in CA-Tools, are ignored.

<nOpenMode> not specified

This opens and initializes the specified COM port. Extended Hardware Buffering will not be enabled. Read Timeout processing will be set to NO_WAIT_READ_TIMEOUT and Write Timeout processing will be set to WRITE_TIMEOUT with a timeout value of 100.

<nOpenMode> == COM_OPEN_FASTUART

With this it is specified that a FIFO-buffering UART like a 16550A is installed. The COM port is opened and initialized. Extended Hardware Buffering will be enabled, Receive Trigger Level will be set to 8 chars and the Transmit Buffer Load Count will be set to 16 chars.

<nOpenMode> == COM_OPEN_NOINIT

This mode is used to get the handle of an already opened COM port without initializing it again (Most useful when a COM port is accessed from multiple threads).

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