I picked up a really nice HP-3421A Data Acquisition Control Unit from eBay. It passes self tests and seems to be working fine. My 41C HP-IL module is having problems, so I am using my 75C as a control unit, but I having trouble figuring out how to read back a result.
For example, I can:
ASSIGNIO (and I assign names :PR and :D to printer and DACU)
PRINTER IS ":PR,:D"
PRINT #2;"DCV7"
(this way I can trace messages on the printer)
This causes the 3421 to click and the LCD display shows 7 as it should. A measurement should be available for reading.
How do I get the measured value into the HP-75C?
It doesn't like my variations on the line:
READ #2,1,A
I haven't programmed file IO on the 75, and don't know how it handles devices vs. files as yet. If it would help, I have the extended IO ROM (whatever it is called).
Any clues would be welcome.
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