ZX Computing
1st December 1986
Publisher: Red Boxes
Machine: Spectrum 48K/128K/+2/+3
Published in ZX Computing #32
Red Boxes
Carol Brooksbank courts domestic chaos to try out the Red Boxes home automation kit
What is your Spectrum doing while you are asleep, or out of the house? Not a lot, I suspect, unless you are an electronics wizard. But it could be the key to a system which protects your home against intruders, opens the garage door, turns a light on when you walk into a room, or anything you can think of, so long as you can plug the appliance you wish to control into the ring mains.
The Red Boxes starter pack contains three modules, Red Leader, Red One and Red Two. Despite the awful names, it is a very ingenious system. Red Leader is the microcomputer which controls the system, and it uses the Spectrum as its monitor as a programming terminal. After programming, it is disconnected from the Spectrum, leaving the computer free for normal use, and runs the system independently. The program is retained until power to the computer is switched off. Red One is a slave switching device, incorporating a 13 amp socket, plugged into the ring mains with the appliance to be controlled connected to it. Red Two is a slave infra-red sensor, also plugged into the mains, which detects movement in its vicinity by responding to the change in heat levels. The link between the controller and the slaves is the mains ring, whose cables carry the messages between them. This makes the system very flexible and easy to install. The only electrical expertise needed is the ability to put a plug in a socket and switch on.
Red Leader
To program Red Leader, you connect it to the Spectrum via the cassette sockets. LOAD"" is entered, and switching on Red Leader causes it to download its control program to the Spectrum. The handbook could be more helpful here. It matters which way the jackplugs are connected to the Ear/Mic sockets, but the handbook does not say so, or tell you which is which. Get it wrong and the program crashes.
Each slave device has a unique code number, known only to the owner, which must be entered into the control program. Only a burglar or an expert hacker could tell you whether this, coupled with the random coding of messages between devices, makes the system tamper proof. I am neither, so I will take the manufacturer's word for it, especially as the rest of the system performs as they say it should.
The built-in clock is easily set, and devices can be programmed to go on and off at specific times, or can be linked together, so that a light or an alarm connected to Red One could go on when Red Two detects movement. They can stay on for a specified period, until a particular time, or until switched off manually. Operations can be performed once or repeated daily.
The Spectrum screen shows the current "ON" or "OFF" status of all devices, and the times and links programmed. The program can be saved to tape but, again, the handbook is less than helpful. When you enter the KEEP (save) command, the screen goes blank except for a cursor at the top, there is no response to the keyboard and the Spectrum emits strange buzzings. Since the handbook neglects to say that this is normal - the program is being downloaded to the Spectrum - you assume a crash and unplug everything. After a third try, you decide to let it go on and see what happens, and eventually the buzzing stops, and the screen prompts for the SAVE operation appear.
Red Basic
For more complex control, incorporating random switching, changing links between devices etc, Red Leader has its own built-in Basic. There are no Spectrum keywords used; commands must be spelt out in full. In addition to the common Basic commands, there are special ones like TELL, used to change the ON/OFF status of a device, or INSTALL, to link a new device to the system. The date can be programmed, and incorporated into instructions. The status of devices can be read and returned as a string. It took me some time to discover that the bug in my program was caused by the ON string being "ON". erversely, On when used with the TELL command has no space. Despite such small irritations the Basic is very powerful, and only your own programming ability limits the complexity of the systems you can devise.
There is no doubt that efficient and sophisticated automation and security systems can be developed with the Red Boxes, but I have some reservations. One is cost. There is really very ittle that you can do with the unexpanded starter system. Mounted 2m above floor level, Red Two can detect human movement up to about 4m away in a direct line, decreasing as the angle sharpens. Most rooms would require at least two, covering the door and window areas, for real security. At £34.95 each, I will leave you to work out the cost of total cover for your home. Each Red Two needs its own power point, which would make it impractical in most houses I have been in. Red One could be used for an alarm, but if you also want to turn lights on and off to give an impression of an occupied house, you will need more of those at the same price. It may be possible to make a less pricey system, using window and door switches and pressure mats the manufacturers are developing, and less Red Twos, but no details or prices are available yet.
The red boxes are smart but, dotted around your home - some of them 6ft up the walls - with their bright red cables trailing to the nearest power point, will hardly blend inconspicuously into your decor. The system will probably appeal most to someone venturing into home automation, who can expand it gradually, or to someone interested in networking computers, because an RS232 device is also planned. No details are given, but it suggests possibilities for networking with no linking cables other than the ring mains.
This is an interesting system, and great fun to use, but the £129 for the starter pack has to be seen as the first of many payments if a practical system is to be put together.