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Serial_Open (function reference)

By July 1, 2023July 17th, 2023Online Help, Troi Serial Plug-in
Troi Serial Plug-in for FileMaker Pro


Opens a serial port with this name and the specified parameters.

SyntaxFunction badge

Serial_Open ( switches ; portname ; settings ; filename ; scriptname ;
              matchstring )


switches (optional) specifies how this function receives the data
portname the name of the port to open
settings (optional) specifies the setting of the port like the speed of the port, parity, etc.
filename (optional) the name of the file which contains the script to trigger when data comes in
scriptname (optional) specifies the name of the script to trigger when data comes in
matchstring (optional) a string that must be matched before the script is triggered


switches can be one of this:

-ResumeWhenScriptPaused when the trigger script needs to run, and an other script is already paused, the paused script will resume after the triggerscript is finished.
-NoIdleWaitTime don’t add idle wait times, the triggering will be faster, but the plug-in will need more computer time.

Returned Result

Data type returned

Error code


Returned result is an error code. Returned error codes can be:

0 no error the port was opened
$$-50 paramErr there was an error with the parameter
$$-108 memFullErr ran out of memory
$$-97 portInUse could not open port, the port is in use
$$-4210 portDoesnotExistErr port with this name is not available on this computer
$$-4211 allPortsNullErr no serial ports are available on this computer

Other errors may be returned.

Originated in

Troi Serial Plug-in 3.0


FileMaker Pro 16 to FileMaker Pro 2023


If you specify a filename and scriptname any scripts specified with the function “Serial_SetDispatchScript” will be ignored for this port.

If you specify a filename you must also provide a scriptname.

Version 6.0 added the (optional) matchstring parameter, you can now specify directly when opening a port the string for which the plug-ins waits before triggering a script.


Set Field [ gErrorCode ; Serial_Open ( "-Unused" ; "COM2" ; "baud=19200 parity=none      
               data=8 stop=10 flowControl=DTRDSR  flowControl=RTSCTS" ) ]

will open the COM2 port with a speed of 19200 baud and the specified options.

Example 2

Set Field [ gErrorCode ;
	Serial_Open ( "-Unused" ; gPortName1 ; 
		gSpeed & " " & gStopBits & " " & gDataBits & " " & gParity &  " "& gFlowControl ;
		Get ( FileName ) ;
		"Process Data Received for 1st Port"

This will open the port in field gPortName1 with the specified speed and other options. When data comes in the script “Process Data Received for 1st Port” in the current filename will be triggered.

Used in example files


Related functionsFunction badge


Related script stepsScript step badge

Open Serial Port
Set Serial Direct Insert

Related topics

Troi Serial Plug-in online help (overview)

Online Help Page for Troi Serial Plug-in for 16 to 2023 –> Serial_Open (serip4805) 2023-0717 12:52:51