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Differential Thermostat

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Delphi Differential Thermostat

This tutorial was put in level 5 for a number of reasons.

-- It relates to a large program.
-- As delivered, it requires that you have an external device, called a Poseidon. (You don't need one- see below.)
-- As delivered, it requires that you add components to your Delphi compiler.
-- There are bits of the coding which I am not 100% certain "work" every time!

So much for the bad news! The good news is that the sourcecode is provided, and you can get lots of good stuff out of it, if you will pick through "the bones". It would also be possible for an intermediate programmer to re-write the program, fixing it to read data from another source. Alternatively, this program might be your way into the world of serial i/o.

The work was done using Delphi version 2.

In a nutshell: The program looks at two temperatures. When one is too much higher than the other, an output is turned on. Typically, this might be used in an atrium with a tendency to get very hot in it's upper reaches. The output would control a fan, to "stir" the cooller air from the lower levels with the hotter air in the upper levels. Note that this is a differential thermostat. If the upper reaches were 25 degrees, and the lower reaches 20, you might want the fan on. On another day, the upper reaches might be 20 and the lower reaches 15... again... you'd want the fan.

The program is written to use a Poseidon to sense the temperatures, and to provide the output. It is a neat device which attaches to the controlling computer over your LAN. You can replace the "offending" bit of code, if you want to use different senors.

I'm not going to say much more here.. the program... which does work, usually!... isn't really finished, and I suspect a limited audience. I'll try to polish the program, and then redo these notes for you. "Need" them sooner? Email me! You should also consult the program's helpfile, limited though it may be (at 6/05, anyway), which is also included with the sourcecode.

The program.....

One "feature" you may find interesting: The program can send strings of SNMP information to the Poseidon to the OIDs in its MIB which relate to the Poseidon's outputs.

I hope you found it useful... Remember there is a link for downloading the program and it's the source near the top of the page.

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