34970 Resistance and Voltage configuration

[hasse]

Hi, I am using LabView 2011 with Agilent 34972A. I use the driver 34970 and I measure temperature (resistance) on ch 101-103 and voltages on ch 104-107.

When I run this and channel 104-107 is open I got a false voltage reading around 2.7V at ch104 and 0V at ch105-107. The temperature reading at 101 is 26C.

If I run just the voltage vi by itself it will give me 0V on all channels (104-107) which is right.

Why am I getting 2.7V, it seems like the voltage vi vill start with some scrap values from the resistance vi?

[JoshY]

Hi Hasse,

Why are you using the drivers for the 34970? There are drivers for the 34972A found here. Also, do you still get this 2.7V reading when different inputs are connected or if you do the voltage reading first?

[ben64]

Try adding the *WAI command between the RTD and Voltage measurements (using the VISA Write function). What module are you using?

Ben64

[hasse]

Hi Ben,

tried to add *WAI as you said. Didn't work - still the same problem. I am using the 34902A 16 ch mux card.

[hasse]

Hi Josh

Your link gets me to the same driver I am already using (Agilent 34970). It say it will support both 34970 and 34972. I can't find any other driver.

If I switch to the voltage reading first and then the RTD reading doesn't matter, it has the same result. Also when using other inputs for example 7and 8 the

2.7 will be read at inp 7. It is always the first voltage input that reads a high voltage no matter which input I am using. It looks like some buffer is not cleared.

[hasse]

Additional testing - when I change the voltage range from 10V to 1V at the EZ Voltage vi, the reading from any input (first value only if I select several) will read 9899999999 !

[hasse · Accepted solution]

It works now after I connected a voltage to ch 104. It seems like the instrument doesn't like an open connection.