The goal of this project is to develop a simple, reliable and relatively inexpensive kiln or furnace controller. Rather than employing specialized controller units, the control logic is done with a personal computer. Thermocouple input is via a meter with PC interface. Control outputs are via X10 "home automation" units.
I have built a "proof of concept" controller and used it to run several kilns, mostly rated at 120 volts, 14 amps. The heart of the system is SIMP-CON, a PC program which incorporates digit temperature measurement, ON-OFF control signals, data logging, and over-heat protection.
Some caution needs to be taken in applying this to a furnace, rather
than a kiln or annealer, because the controller has been written for
use with a Type K thermocouple, and generally these shopuld not be used
above 2000°F.
The program can be downloaded from this site using a link below.
If you are interested in the "why," follow the link.
I do not plan to commercialize my controllers. While they will be based primarily on components which are UL, CE, or CUL approved, the overall design will not be, and you are hereby warned that the information is to be used at your own risk - risk of injury, legal action, insurance claim denial, etc. I will be happy to explain what I have done, but I will not make recommendations as to what others should do.
There a number of reasons for using a personal computer as a major component of a control system. These include:
The X10 home automation has been around for years. Controllers available allow the use of desk-top or wall mounted push buttons, hand-held devices similar to garage door openers, a variety of timers, telephone responders, and computer interfaces. Other than controllers, only a few data input devices are available. "Security system" devices include door/window switches, motion detectors, infrared room occupancy sensors. There are "thermometer" devices, but these operate only in the -10 to 120 °F range. Output devices commonly available include wall switches, plug-in lamp and appliance modules, sirens, home heating thermostat setbacks, and lamp socket modules. Somewhat more exotic, but readily available units include vanes for heating and air-conditioning ducts, security light flashers and phone dialers,
Radio Shack sells X-10 as Plug ‘n Power®. IBM "Home Director," and various Magnavox, Stanley, HomeLink, and Safety 1st controllers are all basically X10 devices, and are all rumored to be made by X10.
I'm not going to duplicate information available online here. X10 itself has a web site at http://www.x10.com. Another major source for X10 information and products from a variety of manufacturers is Smarthome.Com®, who can be contacted at 800-762-7846 as well as on the Internet at http://www.smarthome.com. They have a catalog which runs to about 125 pages.
Eventually I plan to write control programs for MS-DOS® in QuickBASIC® and for Windows® using VisualBASIC®. I plan to support both the standard serial computer interface, as supplied as the IBM "Home Director," and the FireCracker interface. At the moment I am working on the DOS-Firecracker version.
A fairly complete description of the construction, programming, and operating of my first system is available on this site. Click the title above to link to it.
I don't plan to sell my code, and will follow the "open source" tradition of posting most source code as well as compiled versions. The user accepts all responsibility or the use and abuse of the programs.
The programs are currently accessible as source code in the files below which can be run and/or compiled with Microsoft QuickBASIC. My attempts to run some of the same source files with QBASIC result in a "subscript out of range" error. You will probably want to rename the files you download with a .BAS extension.
The executable (working program) files are provided in ZIP
format. This is for two reasons; first, ZIP files are compressed
to a smaller size for faster transmission, and second, my web
host handles them more readily. To convert a ZIP file to an EXE
file you need an "unzip" program. If you don't have
one, you can obtain a shareware version by searching the web. I assume
you know how to download and UnZip the files if you have enough
experience to undertake the project.
SIMP-CON.TXT - A fully functional controller for a kiln, using the X10 FireCracker and Appliance Modules for output and a MeTex meter for thermocouple input. The program allows up to twelve segments in a run, and any segment can be either a "ramp" or a "soak."
Click here to access the .EXE file SIMP-CON.EXE in ZIP format The ZIP file is about 46 K in size, the EXE file is about 75 K.
DEMO-CON.TXT - A version of SIMP-CON which has the thermocouple input and control outputs de-activated so that you can see how the program works without constructing the required hardware. SIMP-CON will lock if input is not provided.
Click here to access the .EXE file DEMO-CON.EXE in ZIP format The ZIP file is about 46 K in size, the EXE file is about 74 K.
The following short programs contain routines which may be useful to other programmers. You may freely download them (they are in text files) and use them. If you use them, PLAY FAIR, credit me in your footnotes, etc.
READ-DMM.TXT - A short program which reads a digital multimeter with serial PC interface attached to COM1. Assuming input from a thermocouple and in millivolts, the program then uses a look-up table to return a temperature in F°.
FC-TEST.TXT - A short program which demonstrates how to send signals to an X10 FireCracker interface from MS-DOS using BASIC. Signals my be sent to COM1 or COM2, assuming standard COM port addresses. Unit controlled must be set on House Code A, Unit Code 1. Messages supported are ON, OFF, DIM, and BRIGHT.
You may contact me at wallace.venable@mail.wvu.edu.
Page revised 20 July 2009.