Python command: Serial Port

The Serial Port commands in Python allow you to connect to a COM port and send or receive data. This command uses an indexer to allow multiple connections, see Python command: SQL. It has no default connection
All connections are temporary. See Python commands for other commands you can use with GainSeeker. It is recommended that you use the Serial Setup action to configure your serial port connections.

See Python commands for other commands you can use with GainSeeker.

 

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Serial port command table

Syntax

Example

Description/Remarks

serial[x].allowkeyboard

serial[0].allowkeyboard = True

Set to False to prevent user from temporarily switching to Keyboard input by pressing CTRL+K on the serial input window.

Defaults to True.

Can affect the behavior of the serial[x].readcolumn command.

serial[x].baudrate

serial[0].baudrate = 9600

Gets or sets the baud rate. Defaults to 9600.

serial[x].bufferlen

print serial[0].bufferlen

Returns the current length (in bytes) of data in the read buffer. -1 if the port is closed.

serial[x].clearbuffer()

serial[0].clearbuffer()

Clears the current contents of the serial port buffer.

serial[x].close()

serial[0].close()

Closes an open serial port connection.

serial[x].databits

serial[0].databits = 8

Gets or sets the number of data bits, usually 7 or 8. Defaults to 8.

serial[x].eolstring

serial[0].eolstring = "\r"

Gets or sets the end of line character(s). This is used by the serial[x].readline() command. Defaults to "\r".

serial[x].filemode

serial[0].filemode = True

Set to True to set the serial port to file mode. Used for compatibility with serial port redirections. Defaults to False.

serial[x].handshake

serial[0].handshake = "None"

Gets or sets the handshake, valid values are "None", "Xon", "Rts", or "RtsXon". Defaults to "None". "Rts" indicates that hardware flow control is used. Values are not case sensitive.

serial[x].isopen

print serial[0].isopen

Returns True if the port is open.

serial[x].maxbuffersize

serial[0].maxbuffersize = 1200

Gets or sets the size of the read buffer. Default will vary based on hardware.

serial[x].message

serial[0].message = "Weigh item now"

Sets the message displayed to the user while waiting for input from the serial port when serial[x].readline() or serial[x].readcolumn() is called.

serial[x].open()

serial[0].open()

Opens a serial port connection. Returns True if successful.

serial[x].parity

serial[0].parity = "N"

Gets or sets the parity. "N" = None, "E" = Even, "O" = Odd, "M" = Mark, and "S" = Space. Defaults to "N" (None).

serial[x].portnumber

serial[0].portnumber = 3

Gets or sets the port number. Defaults to 1.

serial[x].readall()

print serial[0].readall()

Reads the entire contents of the buffer and returns it as a string.

serial[x].readcolumn(index, spliton=",", isnumeric=True, noempty=False)

print serial[0].readcolumn(1, ",", True, True)

Performs a readline() and then splits the output into columns based on the character specified by spliton.

Returns the value for the specified column index returned by the split. If user switches to keyboard input and submits data, this command returns the value for column index 0.

If isnumeric is True, the value to be returned should be a number.

If noempty is True, empty columns are automatically removed and not counted for the index.

serial[x].readline()

print serial[0].readline()

Reads a line of content from the buffer and returns it as a string. A line is defined as a string that ends with the characters specified in the eolstring property.

serial[x].readsysdefaults()

serial[0].readsysdefaults()

Reads the system settings for a particular serial[x].portnumber. Returns True if successful.

serial[x].stopbits

serial[0].stopbits = 1

Gets or sets the number of stop bits, valid values are 1, 1.5, or 2. Defaults to 1.

serial[x].write(message)

serial[0].write("signal")

Writes the specified message to the serial port.

Sample RS232 script

Following is a sample RS232 script to read a value from Channel A or a GageWay 5 Plus.

 

#Script name: RS232

 

#setup parameters for COM port 3.  Using 9600, N, 8 1.

serial[0].portnumber = 3

serial[0].baudrate = 9600

serial[0].parity = "N"

serial[0].databits = 8

serial[0].stopbits = 1

serial[0].handshake = "None"

serial[0].eolstring = "\r"

serial[0].filemode = False

 

#open the COM port

serial[0].open()

 

#this code reads in a value from a Mitutoyo Gage on a Microridge GageWay 5 Plus

#assumes the device output is similar to:

# 199.9\r

 

#Tell the GageWay to send a reading from Channel A

serial[0].write("<RA")

 

#read the value from the COM port buffer

strInput = serial[0].readline()

 

#do something with the value here.  For this example, just write to the debug console.

print strInput

 

#All done, so close the serial port. This is not really needed as all serial ports get closed when the script finishes.

serial[0].close()