Products > Test Equipment

please dont purchase PC controlled test equipment

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Berni:
There is a time and place for everything.

All reasonably modern reputable test gear supports SCPI without the need for special software. The PC control only versions of test gear is simply the same instrument with the front panel ripped away. Useful for packing as much gear as possible in an industrial test system rack.

The issue comes with gear that was originally designed to ONLY be PC controllable. Those are often optimized to offload as much of the work to the PC as possible, so that the hardware could be cheaper. This is impossible to do without having proprietary PC side software. For example there are realtime spectrum analyzers that are just a calibrated SDR in a box, then the PC uses there massive amount of processing power to actually FFT that very quickly.

Yeah i don't necessarily like this way of doing things, but it does make things more portable for people that need it. However if the piece of PC controlled gear is cheap it doesn't really matter if you have to throw it away once the software support is gone. Like for example i am a fan of those little USB logic analyzers. They are little dumb boxes that just barf the state of digital pins into the USB port and let the PC actually take care of any processing or storage. This makes the really cheep and tiny. At the same time the software is nicer to use with a mouse compared to a old huge boatanchor logic analyzer. It takes up very little space on your bench...etc. The cheap SDRs can also be very capable modulation analysis equipment.

So there are cases where a PC controlled instrument is a good idea.

DavidKo:
The simple answer is cost.

In past buying a HPIB (GPIB) interface was not cheap. To sold single instrument which needed PC to operate to someone with its own PC was cheaper than pushing him to buy instrument (with PC inside), GPIB interface, cable etc. Now the situation is opposite and SW solutions tends to be cheaper than HW solutions (like software defined radio, which can substitute more devices at once) and powerful computers are cheap. Cheaper solutions wins for the buyer, since he need to pay price now, not after selling the device second hand.

TomKatt:

--- Quote from: JPortici on March 06, 2023, 03:51:27 am ---It's not uncommon at all. Industrial machinery can cost tens to hundreds of thousands and is build to a certain degree of quality. Ten years ago when i dabbled in internships in that area it was no strange to find machinery with windows 3.11 PCs controlling them. The idea of scrapping a perfectly good (and costly) machine because the computer is outdated is ridiculous, but that means that you have to be able to keep the old pc running

--- End quote ---
LOL - We have a CNC running on Windows NT right now  ;D

We have spares for most of the pc controller parts, but some items like ISA controller boards can be difficult to source.

And it is a real shame to basically scrap the machine because it's brain dead.  I still find it hard to believe that it can be cheaper to replace the entire machine rather than simply upgrade the controller, but in virtually every case we've encountered that's how it works out.  I'm sure given some time and resources we could refurb those things in-house, but in a commercial manufacturing environment, time is money and also floor space real estate is limited (these are large machines)...  It simply isn't feasible to revamp them ourselves.

I don't think there is really a good answer - pc control does offer the most flexiblity and bad as it is it's still easier to deal with than proprietary PLC controllers.  I'm sure someone must be refurbing these things on the used market, but we purchase used equipment frequently and I've rarely seen one that has been refurbed with new controllers.

Berni:
Yeah CNC machines are often run by computers from the stone age.

I am guessing the reason they don't get upgraded is logistical difficulties of having the space for it and hauling it around. If it is in a factory it needs to be worked on in place, being in the way. If someone else wants to fix one up and sell it then they need to haul the massive metal behemoth over to there place, fix it up, then haul it to the costumer. Also when they get the machine, they might not have any idea of the condition of the mechanical parts. It is possible the ways,bearings,ballscrews..etc are worn to hell and have heaps of slop, maybe the machine had a bad crash in its history that bent stuff etc.. So it might not just need new electronics but also some special precision mechanical parts that are also near unobtainable by now too. Even then companies will want someone to call up when the machine breaks, so the guy who refurbishes these things would also have to be the one fixing them. Since they are refurbs every machine would be slightly different so maintenance could get more complicated to provide, especially when the company expects to have the machine back up and running ASAP.

Id guess the dicking around is not worth for companies that just want a reliable machine that will pump out parts all day to make money. After a while the parts pay off the cost of the machine anyway. If it breaks down 30 years later they figure it made plenty of profit anyway, it might be worn to hell by now, so time for a new machine.

Still an excellent project to take on for getting a cheap CNC into the home shop. That is if you have the space for one and find a machine small enough (They are often too massive for what you need). That way the large amount of labor of fixing it up and figuring out how to do it is part of the fun rather than the cost.

TomKatt:

--- Quote from: Berni on March 06, 2023, 01:18:18 pm ---Even then companies will want someone to call up when the machine breaks, so the guy who refurbishes these things would also have to be the one fixing them. Since they are refurbs every machine would be slightly different so maintenance could get more complicated to provide, especially when the company expects to have the machine back up and running ASAP.

--- End quote ---
I know that at least for us, support is rated nearly equally to a machine's ability / features.  Down time costs a lot of money.  So unless a refurbished machine comes with support (including a stocked replacement parts supply), we're not likely to purchase it.  I suspect that many businesses operate with similar requirements.

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