troi.com – Receive Serial Data (script step reference)

Troi Serial Plug-in > Script steps reference > Receive Serial Data

Receive Serial Data

Receives data from a serial port with the specified name.

Syntax

Receive Serial Data [ Select ; Result (error) ; Port name ; Encoding ;
                      Get last match ; Switches ]

Options

Select entire contents	replaces the entire contents of a field with the result. If not checked the result replaces the currently selected portion of the field
Result data	the data received
Port name	the name of the port to receive data from
Encoding	the desired character encoding like UTF-8, or "Convert bytes to numbers" which converts all received bytes to their numeric value, with a space as separator
Get last match	get the last string of text that matches the match string
Switches	(optional) specifies how this function receives the data

Switches

The optional Switches parameter takes precedence over the other parameters. Switches can be:

-GetLastMatch

get the last string of text that matches the match string

You can also add one of these encoding switches, which determine how the incoming bytes are interpreted.

-Encoding=ASCII_DOS
-Encoding=ASCII_Windows	(Windows ANSI)
-Encoding=ASCII_Mac	(Mac Roman)
-Encoding=ISO_8859_1	(Windows Latin-1)
-Encoding=UTF8
-Encoding=BytesOnly	returns all received bytes as the same Unicode byte values (Unicode 0 to 255)

-ConvertBytesToNumbers

converts all received bytes to their numeric value, with space as separator

Returned Result

Data type returned

Text

Result

The returned result is the data received or an error code. An error always starts with 2 dollars, followed by the error code. You should always check for errors when receiving, by testing if the first two characters are dollars. Returned error codes can be:

$$-28	notOpenErr	the port is not open
$$-108	memFullErr	ran out of memory
$$-50	paramErr	there was an error with the parameter
$$-4210	portDoesNotExistErr	port with this name is not available on this computer
$$-4211	allPortsNullErr	no serial ports are available on this computer
$$-207	notEnoughBufferSpace	the input buffer is full

Other errors may be returned.

Originated in

Troi Serial Plug-in 5.0

Compatibility

FileMaker Pro 16 to FileMaker Pro 2023

Considerations

The port needs to be opened first (see Open Serial Port).
If no data is available an empty string is returned.
The plug-in will get any data that is received at the time the function is called. This might not be all data coming in. You might need to wait and append new data coming in at a later time.

When you use the “Get last match” option the last matching string of text is returned. Older text is discarded.

Please be aware that only the ASCII characters 0…255 will be received, as a serial port uses 8 bit characters. If the serial device is encoding the bytes as UTF-8 you can receive any Unicode character. In this case specify as Encoding UTF-8.

When using the encoding “Convert bytes to numbers” all received bytes are converted to their numeric value. It will for example return “65 66 67 “, when receiving the bytes “ABC”. Note that each number is followed by a space, as separator, including after the last number.

Example

Receive Serial Data [ Select ; $Result ; "SerialPort1" ]

This will receive data from the SerialPort1. It might return “All the world is a sta”. If you call it again later new data may have come in and the result might be “ge and we are merely players.” It is best to concatenate the data coming in.

Example 2

Below you find a “Receive Data” script for receiving data into a variable $TempResultReceived. The script tests for errors.

We assume that $PortName contains the name of the previously opened port.

Add the following script steps:

Receive Serial Data [ Select ; $TempResultReceived ; $PortName ]
If [ Left ( $TempResultReceived ; 2 ) = "$$" ]
	Beep
	If [ $TempResultReceived = "$$-28" ]
		Show Message [ Open the port first ]
	Else
		If [ $TempResultReceived = "$$-207" ]
			Show Message [ Buffer overflow error ]
		Else
			Show Message [ An error occurred! ]
		End If
	End If
Halt Script
Else
	# No error, so concatenate the data and do your stuff:
	Set Variable [ $TotalResult ; $TotalResult & $TempResultReceived ]
	#  .... add your own steps here ...
End If
Set Field [ gTotalResult ; $TotalResult // also save into a global field ]