Electronics > Projects, Designs, and Technical Stuff
Automated test equipment for production testing
microherb:
We need to setup some automated test equipment for production testing of an offline power supply LED driver (240VAC traffic lantern).
My idea at this stage is to purchase a programmable AC power supply (such as this: https://www.bkprecision.com/products/power-supplies/9801-programmable-ac-power-source.html )
and a programmable multimeter for reading output current, output voltage and possibly a few other voltages around the board. I would use a bed of nails setup to probe the points of the circuit I would like to measure. (See block Diagram attached)
So I guess I would also need some kind of SCPI relay board to switch the multimeter to read different points of the circuit? What could I use for that or do I just make my own for this simple requirement?
Am I on the right track?
If I used RS232 for the communications would I need multiple point to point RS232 link between the controlling device and the instruments as there is no way I know of to have RS232 multidrop.
Test routine would be fairly simple.
Set AC power supply voltage output
|
Delay
|
Read AC Current, power factor etc,
Read Output voltage and key voltage points.
|
Change AC power supply voltage
Delay
|
Read AC Current, power factor etc,
Read Output voltage and key voltage points.
If I used a PC is there software that is good to use? I've heard of Labview but haven't had a chance to familiarise myself with it and I understand it's expensive.
Or would you typically just write that software test routine yourself in C or something.
This Jig will be sent to the board loader for testing product prior to shipment as well.
So It might be good to make up a small go/no go tester for them using a microcontroller or something.
Thanks in advance for any feedback.
MosherIV:
Hi. You already mentioned Labview by National Instrument.
Unless you want to writ your own test infrastructure, most companies just pay for Labview.
If you cannot write your own test, there are lots of contractors.
NI should have relay boards/cards which can be accessed through Labview.
Or you could look at something likt this
https://www.keysight.com/en/pd-1756491-pn-34972A/lxi-data-acquisition-data-logger-switch-unit?nid=-33257.922596&cc=GB&lc=eng
It takes relay cards in the back. They are design to log from lots of sources.
If you do want to roll your own, try Python. Has lots of library support for many instruments. I think it has support for SCPI. It is easier to learn than C.
Smokey:
Whatever you end up using for the test setup, the number one rule is to have as much of it as possible be commercial off shelf. Don't make custom test equipment unless it's absolutely necessary.
Yes, automated test hardware is expensive. You may think you are saving some money my making your own stuff, but the advantages of having hardware with listed specs, actual warranty/replacements, and services contracts is so worth the extra money. When something dies during the night shift on the weekend, you DO NOT want to be the guy that's responsible for modding/debugging a custom board at 2am to get the thing back up and running.
On the software side, use whatever your "test guy" is familiar with. If you don't have a test guy then stay away from labview if at all possible. Hire/contract a python guy (there are way more of them) before you hire/contract a labview guy.
jbb:
I saw 230V RMS there. That could be quite a stretch for standard relay cards.
For example, the Keysight 34972 DAQ is a great unit (we use them at work) but is only rated to 300V. It says in the manual that it’s not rated to measure the mains. So you probably need a 1000V rated relay setup. I don’t know of any standard products with that rating, sorry.
Does the programmable AC source do all the AC measurement stuff? That would save some trouble.
TheUnnamedNewbie:
Software for this tends to be a common debate at different places I know. Some use LABView, others use python, others still use MATLAB or even high level stuff.
I have to agree with the 'stick to pre-built' stuff, provided this is a critical, long-term test setup. Consider this: Imagine you built something yourself, and it fails, and you can't replace the component. How bad is the fact that you might now have to wait for a few weeks before a new design can be set up to replace it? Not to mention, if you need some kind of certificaiton or whatever it could be required you have calibration information for everything used, and getting that for some custom setup can be more expensive than buying the off-the-shelf verison.
If this is for a commercial setup with a decent budget, consider reaching out to your sales rep from NI, Keysight, etc. They usually know what their lineup looks like and can help you find good parts and avoid gotchas.
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