Improper Voltages being logged in USB PT-104

Hi Martyn,

I am logging DC voltages using PT-104. However, the voltages logged are incorrect. Please see the snapshots.

When I am using multi meter, the voltage shown is 2.5V at the 4 pin Din terminal adapter.

However, the voltage shown by the picolog software is 1.6Volt only.

What could be the problem?

Please help!

Thanks!

Juned

Also would like to add, that the voltage gradually keeps on reducing till it reaches ZERO value in picolog software.

I am really in a fix.

I have to go on site for a test and need this to be addresses urgently.

Thanks!

Juned

What pins are you connecting to?
How are the PT104 channels set up in Picolog ?
Is there any scaling ?
Post a settings file and we can take a look.

Martyn,

I am connecting to pin no. 2 and 3.

Positive of output to pin 3 and negative of output to pin 2. Output is coming from a signal conditioner which is converting 4-20mA to 0-2.5V.

There is no scaling.

Channel 3 and 4 were set for "differential voltage 2.5V". But they are not showing the correct reading. After a certain period of time, both show zero value.

Can you please help?

Thanks!

Juned

Try single ended 0-2.5V and connect +ve to pin 3 and -ve to pin 4 (GND)

Martyn,

Thanks for the response.

In single ended, it is showing almost correct readings. But still, at maximum voltage of 2.5V as shown by multi meter, the picolog software is showing only 2.36V.

How to resolve this?

Juned

I would suggest using Picolog to scale the input to reflect what you see.

Martyn,

I assumed that Multimeter is faulty and picolog values are correct. This solved the issue.

Thanks!

Juned