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| wkb:
Ah, thank you Alain. Non-obvious indeed. Pictures show it now works. The 6-something degr C indication is before the ambient temp was entered into the meter, the 20-something degr C is after that was done. A quick test with a hot air soldering station gave me a quite reasonable measurement as compared to the hot air temp setting. |
| dreamcat4:
so with SCPI commands... maybe we could make a device to enter the ambient temperature over GPIB / external device? And update it every N seconds? :-// [edit] i suppose what i am really asking is: well would that be worth doing, would temperature measurements on specific thermocouples actually benefit for the 6.5 digits precision of this meter? rather than using other dedicated equipment |
| gray5596:
subscribed |
| wkb:
--- Quote from: dreamcat4 on March 02, 2023, 11:51:11 am ---so with SCPI commands... maybe we could make a device to enter the ambient temperature over GPIB / external device? And update it every N seconds? :-// [edit] i suppose what i am really asking is: well would that be worth doing, would temperature measurements on specific thermocouples actually benefit for the 6.5 digits precision of this meter? rather than using other dedicated equipment --- End quote --- Said thermocouple was, I think, something like €2,50 delivered on my door mat, from China. For some run of the mill, casual, temperature measurements that is hard to beat, assuming of course the DMM itself is already on your bench. Wilko |
| alan.bain:
I'd be interested if anyone could test this, but it seems on my 7-5-2 34401A the thermocouple mode is hard coded to use a 5K thermistor (as in you can change the R25 value via SCPI or front panel but it doesn't seem to have any effect on the output measurement). I'd suspect this might be a bug (but I can hardly call it a bug in an undocumented feature!). The conversion from value to temp is done via linear interpolation off a table which is more or less uniform in log(R). It seems to use a beta of around 3850. The other Rs supported should be 10K and 2K2 (at least that's what the input routine parses). The attached graph shows the transform function and a linear regression fit to show it's not using a pure beta law. For quick reference: SENS:TEMP:TRAN:THER:TYPE {2200,5000,10000} view as SENS:TEMP:TRAN:THER:TYPE? I also noticed a strange debug aid for the temp ranges DIAG:POKE 29,0,1 Tells the meter to skip the conversion from measurement to temperature so displays the raw voltage/resistance (you could of course select a DCV or OHM mode yourself....) DIAG:POKE 29,0,0 turns it off. |
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