Measurement Computing DataShuttle - Manual (Page 51)

DataShuttle and DynaRes 11-13-01 DynaRes - Technical Notes 5-5
Troubleshooting: Operation
Hints
During operation, it’s good practice to short all analog input channels you’re not using; to do this,
connect + to – to Com.
It’s essential to have exactly one ground reference per channel. This single connection to ground makes sure
you don’t exceed the common mode range of input.
(More than one connection per channel can lead to ground loops, causing errors or erratic readings.
Connecting the – to the Com terminal provides a single ground. Your sensor might also provide another
ground. If you’re not sure that your sensor is grounded, try connecting the – to Com, and not, and see which
works best.)
Remember that if speed is not critical, selecting the “low noise mode” in software always provides the best
accuracy and resolution with your data acquisition board.
Operating Qs And As
1. Problem: My board reads analog inputs wrong.
Action: Make sure the calibration numbers in the EEPROM are correct (see the discussion beginning
on page 5 – 6 in this chapter). If the figures are correct, try shorting + to – to Com: the board should
return a reading around 0V.
2. Problem: My board reads the thermocouple as a very negative temperature.
Action: Verify the connections are secure. Opens read as negative temperature.
3. Problem: My board reads thermocouple input wrong.
Action: Confirm that the CCAL number in the EEPROM matches the number on the terminal panel’s
calibration label.
(If you need to use a general-purpose terminal panel – one that doesn’t have a factory CCAL number
– with a thermocouple, you can achieve approximate results by entering a CCAL of 22000. Then
change the figure by about 75 points for each degree C. that you want to raise the temperature.)
4. Problem: My readings are noisy.
Action: Try using the low noise mode (see your software manual for more information).
5. Problem: My board used to work, but now the software cannot find it, or reports an error.
Action: Check to make sure the Board Number switch is not set to “0.”
If You Need Customer Support
What to do before calling technical support, to help us serve you better:
1. Have the part numbers of your boards and terminal panels ready.
2. Have the type and version number of the software you’re using.
3. Have your computer’s type, model, and the version of the operating system.