Last month, we described the basics of the PICAXE Net Server (PNS) and built a simple demo board which we then controlled over a local network. This month, we look at how to access the PNS over the Internet.

Once your PICAXE Net Server is up and running on the local network, you’ll no doubt be keen to expand your horizons and control it externally – from a remote location over the Internet. This article describes how to configure a "typical" home network and how to make use of various Internet-based services to enable remote access to the PNS.

A diagram of the network we’ll be referring to in this article appears in Fig.1. Note that this is not intended to represent the ideal layout but rather is presented as an example. In fact, some of the devices mentioned are now quite a bit out of date!

Nevertheless, it’s typical of the network found in many homes.

Fig.1: here's the layout of the network described in the text. Many home networks will use a combined modem, router and switch, simplifying the layout considerbly. The wireless section is obviously not needed for a basic set-up but we've shown it here because most networks will now include wireless components

Connection to the Internet is made via an "always on" cable modem, while a webcam is included so that the author can check that the PNS is behaving as expected. A Panasonic BL-C10 webcam was selected because it can broadcast images without the need for a computer connection. Obviously, you won’t need a webcam for your setup!

Before we explain how to configure the network to support the PNS, it is useful to identify each component and briefly describe its function within the network:

Cable modem (Motorola SurfBoard 4100):in simple terms, the cable modem’s job is to convert the signals on the carrier’s cable network in the street into signals compatible with the local computer network in your home.

When the modem is plugged in and connected to the computer (or router), your ISP automatically allocates the connection an IP address by a process known as DHCP. We described this process briefly last month.

To avoid confusion, we will refer to this address as the "public IP address", as it is visible externally to other computers on the Internet. In most cases, this address will be dynamic, meaning that it will change often – perhaps every time the modem is switched on. For convenience, we will use 82.83.84.85 as the public IP address in our example network.