Fluke 8840A to 8842A upgrade

[johnd01]

When I upgraded a Fluke 8840A to a Fluke 88942A the values returned from GPIB are 10 the display values. Manuals for both meters refer to IEEE-488 Interface PCA part number 879267 Rev D. I tried to use the same GPIB card in both meters. The only GPIB cards I have came with the 8840A meters. Is there a difference between the GPIB cards? What can I try to make make the upgrade work? If we go to newer meters the old software that has been working so well for so long will have to be changed and we really do not want to go there.

Any in site will be greatly appreciated.

[smercurio_fc]

I'm not sure I understand what you're asking here. What does the GPIB card have to do with the fact that the values you're getting are "10 the display values" (is that 10 times the display value?)? Also, I'm not sure why you're asking about Fluke part numbers on a National Instruments board. Have you tried Fluke tech support?

[johnd01]

Thank you for asking for clarification.

If the meters reads 10.0000 I get 100.000 E +0 on GPIB with a Fluke 8842 and 10.0000 E+0 for the Fluke 8840 using the same GPIB card and  NI GPIB-USB-HS.

I am asking here in the hope of finding an old time Fluke user. Fluke's forum is so locked down I could not even ask there. These meters are way out of support but there are a lot of old old test system that use this meter and the cost of changing to a newer system is not desirable. 

These are very stable 200,000 count meters but they are getting hard to get.

[Albert.Geven]

It surely has nothing to do with the gpib card. 

I also cannot imagine that Fluke would use a 10 times higher value on the bus, so maybe you are measuring not voltage anymore but some derived value.

Do you still have the software sources of the program.
If you still have the source you could add a switch to specify which system you have or read it from the multimeter.

[David3131]

John,

Yes the internal IEEE interface card differs between the 8840 and the 8842. Look at U901. The 8842A ROM has P/N 879270 where as the 8840A should have P/N 723122. Try the 8842A ROM. Hope this helps.

[Sparks!]

I had the same experience, however I have an 8842a with the correct U901 to compare with another 8842a using the GPIB card from a 8840a. The displayed values are correct in both cases, but the x10 factor is on the '8840a' GPIB. A python script fixed the problem when using GPIB. This is Python 2.7 and PyVISA on Win7 PC doing a meter comparison:

print 'HP3245 by FK8842'
for x in range(1, 10001):
intf.group_execute_trigger(DMM8842a, DMM8842b)
a = DMM8842a.read()
b = DMM8842b.read()
a = float (a)/10
b = float (b)

c = (a+b)/2
txt = "{:E}"
print (str(x) + ", " + txt.format(a) + ', ' + txt.format(b) + ', ' + txt.format(c))
time.sleep(1) # 1 sec

This is faster and easier than programming the EEPROM.

[patmxa]

Hi there!

Huge shot in the dark here, but any chance you could provide more GPIB command examples for the Fluke E3631A?  I used your DMM.read() example and I'm able to read back voltage perfectly with it, but I can't find resources for commands.  I'm using the pyvisa python module.  I'd like to be able to change between voltage/2-wire/continuity/etc.  I realize that this forum is 12 years old, and have no expectations.  

Thank you!

[Sparks!]

In response to the question about "Fluke" E3631A; there is an Agilent/Keysight bench power supply with that number. I checked eBay and Google for a Fluke with that model number, but found nothing. 

Check your gear and reply.