Products > Test Equipment
Fluke 8840A/AF GPIB board
PaulAm:
I just got a pretty nice 8840A/AF the other day but it didn't have the GPIB option. I've seen a couple posts that include the dump of the firmware but I wonder if anyone has cloned that board? So far, the only schematic I've found uses the NEC UPD7210 controller IC, but at least one of the board versions is supposed to just bit-bang the bus and it would seem not too difficult to clone that board. The NEC IC is still available from the grey market, not sure how much I'd trust that.
To make matters worse, I think the A and A/AF GPIB firmware is slightly different. So I need the right schematic + right firmware + right model.
Any pointers?
coromonadalix:
better buy a defective or ''for parts meter'' normally an gpib board should be fine
Just have to check the option marks on the rear panel when a seller show it
You may face many problems to clone or redo a board ???
PaulAm:
Possibly, but what's the fun in that?
oPossum:
There where many ISA GPIB cards that used the uPD7210. Buy one of those and you would have a uPD7210, GPIB drivers and GPIB connector. Getting the Z8 and proper firmware for it may be a bit more difficult.
I did GPIB for the Fluke 45 using schematics in the manual and it turned out great. Got the TMS9914A, GPIB drivers, and GPIB connector from a HP GPIB module for a DSO.
robert.rozee:
the interface between the 8840A's processor and the GPIB board appears to just be two-wire serial (of unknown format), passed through a couple of isolating transformers to give two balanced pairs. pins 4 and 5 of U202 (8842A schematic) seem to be the TTL level RxD and TxD. when i bought my 8842A there was no GPIB board fitted, and instead the cable that would normally run up to that board was brought out to an 7x2 berg connector sitting in place of the GPIB socket. see:https://xdevs.com/doc/Fluke/8842A/img/rear_1.jpg. i obtained a GPIB board on ebay and fitted it a number of years back, but have never actually tested it.
i'm a little surprised no one has got in and snooped on pins 4 and 5 in order to figure out the protocol and what data is exchanged. you could then replace the GPIB board with a small micro to translate to/from RS-232 serial. much simpler to work with these days.
cheers,
rob :-)
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