Control Matters SPLat Controls' aperiodic newsletter

03 Feb 10 View online

SPLat/PC 32-bit - new release.

A recent release of SPLat/PC, V10.21.2, has been causing a few users some grief. The program creates a number of file folders and files for its own internal use (for example the .ini file and a startup log file). We tested it all inhouse on everything from XP 32-bit to Windows 7 64-bit and had no problems. That hasn't stopped users having problems, of course! Murphey is alive and well.

Anyhow, we've been banging away to fix it up, and have just released V10.21.3. This version attempts to tow the Party (a.k.a Microsoft) line about where applications should and should not create "private" files. If the operating system does resist, the program will generate an error message on the screen and then carry on (rather than just crash out).

So roll on up and get your copy here, and please, please, report any problems along with your operating system details.

David Stonier-Gibson

When not to trust the electronics

Modern electronics are extremely reliable, especially if well designed and used correctly. Nevertheless, silicon chips contain features smaller than the wavelength of light, and control programs contain many thousands of lines of program code. Electronics can (and do!) fail, be it due to electrical failure or imperfect programming.
 
Would you bet your life on the electronics not failing? I wouldn't, and I make the stuff!
 
Any industrial machine that can hurt people should be fitted with safety cutouts and interlocks. The most common safety measure is the emergency stop, sometimes called E-stop or mushroom switch. On conveyors it would be a rope switch. It could also be a fence or physical guard barrier with a safety switch. These are wired so that if activated they immediately remove power from the machine or otherwise inhibit it from making a dangerous move.
 
Do not ever even think of wiring the safety switch to the controller and having the controller stop the machine. Always wire the safety switch directly into the machine in accordance with safety design rules in your location. If the safety switch has an auxiliary contact, by all means wire that into the controller so it can know what has happened and not get upset, but do not expect the controller to make safe.

Do not treat this as expert advice. If you are in the least bit of doubt, consult an expert.  

Out of control - Nothing much to do with controls, (but interesting)

How do transistors really work?

Those of us who have been through some formal education in electronics will have been presented with explanations of how bipolar transistors work. In some case we will have been fed a bunch of equations with no "gut" feel. In other cases we will have received descriptive explanations that didn't quite seem to make things very clear.

I recently discovered a website that contains a very nice, and quite believable, description of the internal workings of a transistor by William Beatty, BSEE. Bill argues that they are not current controlled as popularly believed, but voltage controlled. It makes sense to me. You can see Bill's description here.  

Have you seen our easy to digest Finite State Machine tutorial?

Q: How do you drive an engineer completely insane?
A: Tie him to a chair, stand in front of him, and fold up a road map the wrong way...

With most men, unbelief in one thing springs from blind belief in another.
Georg Christoph Lichtenberg 

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