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Fluke 87IV please whisper in my IR :P
frenky:
//I'm posting this here because someone might find it useful. And it doesn't fit into repair section because nothing was broken..
So I fixed my new/old Fluke IV and it's working great: https://www.eevblog.com/forum/repair/fluke-87-iv-repair-log/
I wanted to use IR-USB feature of Fluke IV to send data to PC. After some googling I found cables which are crazy expensive... About 60$-80$ + shipping.
So I started to look for alternatives and found this schematics:
http://www.itsonlyaudio.com/measurement/fluke-123-opto-isolated-cable/
Well that looks easy. I had most of components at home and put together this:
And here are serial commands:
http://www.pewa.de/DATENBLATT/DBL_FL_FL187-9-89IV_BEFEHLSSATZ_ENGLISCH.PDF
So I opened RealTerm and sent ID<CR> trough it and .... nothing. I should get back something like: "FLUKE 87,V0.39,123456789" but no...
I then tested if my module works by putting spoon in front of it. It worked. All commands were now echoed back to RealTem.
So why was not my dmm responding...?
frenky:
So my next thought was there must be something wrong with the schematics because it was too easy. ;D
And then I found this one:
http://kimboricha.blogspot.si/2013/12/build-usb-to-fluke-189-irinfrared.html
This time I did not bother soldering it:
I tested it again with FlukeIV and nothing. DMM just would not answer to any of my requests...
Now that I had two modules I tried if they can talk to each other and yes I could send data from one module to another trough IR with no problem...
frenky:
It was time for some investigation...
I looked at IR diodes on pcbs of similar models online. 189 is a successor to 89IV and model 187 is a successor to 87IV.
189: More photos: http://mrmodemhead.com/blog/gallery/fluke-189-clean-up/
187: More photos: https://www.eevblog.com/forum/testgear/fluke-187/msg536864/#msg536864
89IV:
And my 87IV:
Hmm.... ;)
frenky:
So the IR module does look a lot different in old models.
HPL845 did not return anything so I started to look for similar IR modules.
Based on looks and number of pins and power and ground lines I have found HSDL-3201 as a peffect match:
http://media.digikey.com/pdf/Data%20Sheets/Lite-On%20PDFs/HSDL-3201.pdf
frenky:
So I studied the datasheet of HSDL-3201 and found out this interesting parts:
"Output is a low pulse for 2.4 µs when a light pulse is seen."
and
" Logic high turns the LED on. If held high longer than ~ 20 µs, the LED is turned off. "
So this module can't work with just regular SIR (Serial to Infrared) because at 9600 baud rate bits are 105us long and if transmitter is only outputting 20us long pulses serial2usb ic won't understand "serial" data that is getting on RX.
So I learned that this HSDL-3201 is used for IrDA protocol which is quite different from serial:
Veri nice article about IrDA: http://www.eix.co.uk/Articles/IrDA/Welcome.htm
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