Python Programming On Win32

The Serial Module

Our preferred route for serial I/O with Python is Roger Burnham’s Serial package. This is free and comes with an installer and several examples.

The Serial package is based on a set of serial communications libraries developed by MarshallSoft ( www.marshallsoft.com) over the last eight years. These libraries are available as a 16- and 32-bit DLL with identical interfaces, which makes it easy to migrate applications from 16- to 32-bit and back again.^[1] The libraries are available as shareware packages for Visual Basic, C, and Delphi. MarshallSoft have kindly allowed their DLL to be used free of charge as part of the Python package provided a brief message is included with any distribution. The core DLL is not Open Source but has been heavily tested and won several awards.

The Serial package uses SWIG (see Chapter 22 ) to create a Python DLL wrapper around the library, and provides easy-to-use Python wrappers and examples. The Python wrapper class is Open Source and provides a simple high-level API that simplifies many common communications tasks. The Serial package provides functions to open and close serial ports and to read and write from them.

The art of telephone conversation

The “Hello, World” of the communications field is to send an AT command to a modem and get back a response, so we will take care of this formality first. If you are not familiar with modems, they almost all speak a common command language defined by Hayes; the computer sends a line of ...