PLC Programming Dilemma

I was at a customer today fixing a database problem, and they asked if I would help with some PLC programming. They know I can do so it is not a completely of the wall request. Now I need the work so I will probably end up taking the job, but I really dislike PLC programming.

One reason is that most of the programming techniques I take for granted must be thrown out. Take unit testing, for example. You simple can't unit test a PLC program without buying very expensive simulators. Well, if you run big bucks corporation, maybe it doesn't look expensive, but for my customer who is struggling at the other end of the scale, the pricing is out of the question. The problem is that, of all the PLC programmers they might use from time to time, I'm the only one who would actually use the simulator. Even the best PLC programmer I have ever known, had never even heard of unit testing. Testing? Just do it on the robot.

Another reason is that Ladder Diagram (LD) programming sucks. To me, it is just glorified assembly language and who uses assembler for complex systems any more? There are 4 other languages one could use. The graphical language called Structured Function Chart (SFC) is the most interesting. The Structured Text (ST) language looks a lot like Pascal. I've never had the opportunity to use any of them because LD is so entrenched in the automation industry that using LD will never be questioned. It is the risk free choice because you can guarantee that there be someone in the plant who knows LD well enough to tweak a machine. (OK, they might have some trouble with my non-standard programming style, but that's another story.) Fact is, very few maintenance staff will know the other languages.

Finally there is the plethora of different programming interfaces, one from each PLC manufacturer. Sometimes, I think they intentionally go out of their way to make the user interfaces as different from the competitor's as humanly possible. If you use them everyday, I'm sure you get use to it, but for occasional users like me, it is just a pain.

I will stop ranting now. I could go on about this all night. :)