=================== Installation ==================

To use this dlm, place the following files in the C:\rsi\idl56\bin\bin.x86 folder.

  serial.dll
  serial.dlm

=================== Documentation ================

FUNCTION
	COMM_OPEN

SYNTAX
	h=COMM_OPEN(port [, BAUD=value][, BUFFERSIZE=value]
		[, DATA=value][, MODE=value][, PARITY=value]
		[, STOP=value])

RETURN VALUE
       Returns a handle.  This handle is passed to the other functions.

ARGUMENTS
	port - Specify the serial port, for example: 'COM1', 'COM2', ...

KEYWORDS
	BAUD - An integer baud rate, for example 9600, 19200, ...

	BUFFERSIZE - Request an internal buffersize (number of bytes).
		   If this is not present an OS default buffersize is used.

	DATA - The number of data bits.  Normally 8 or 7.

	MODE - Open the port for:
	     0 = Query mode only
	     1 = READ only (Default)
	     2 = WRITE only
	     3 = READ/WRITE

	PARITY - Use one of the following:
	       'N' = No parity
	       'O' = Odd parity
	       'E' = Even parity
	       'M' = Mark parity
	       'S' = Space parity

	STOP - Number of stop bits, 1 or 2.



FUNCTION
	COMM_CLOSE

SYNTAX
	result=COMM_CLOSE( [handle] [, /ALL])

RETURN VALUE
       Returns the number of successfully closed handles.
       Non-zero indicate success.

ARGUMENTS
	handle - Handle returned by COMM_OPEN.  If handle is not specified /ALL must be.

KEYWORDS
	ALL - Close all handles.  The handle argument is not required when /ALL is used.


FUNCTION
	COMM_READ

SYNTAX
	result=COMM_READ(handle [, BUFFER=variable][, NMAX=value][, NOUT=variable]
				[, OFFSET=value][, TRANSFER_COUNT=variable])

RETURN VALUE
       Returns the data that is available on the port as an array of bytes.
       If no data is available integer -1 is returned.
       To check if no data was read use "IF (result[0] eq -1) THEN ..."
       If the BUFFER keyword is present, then the return value is an integer
       indicating how many bytes were read.  The actual data read is then stored
       in the variable specified with the BUFFER keyword.

ARGUMENTS
	handle - Returned by COMM_OPEN.

KEYWORDS
	BUFFER - Use this keyword to read data from the port into an existing
		 IDL variable instead of allocating new memory.

	NMAX - Imposes an upper limit on the number of bytes to read from the port.
	       Note that the actual uppper limit may be lower than this due to other
	       constraints.

	NOUT - A variable that will contain the actual upper limit specifying how
	       many bytes were actually attempted read.

	OFFSET - Specifies a byte offset into the variable specified by the BUFFER
		 keyword.  This allows for reading into the same variable repeatedly
		 without overwriting the data that has already been read.

	TRANSFER COUNT - A variable that will contain the number of bytes read.


FUNCTION
	COMM_WRITE

SYNTAX
	result=COMM_WRITE(handle, data)

RETURN VALUE
       Returns the number of bytes successfully written to the port.

ARGUMENTS
	handle - Returned from COMM_OPEN

	data - A scalar or array of a basic datatype that will be
	       written (binary write) to the port.