Railing Voltages on PCI-6036 Analog Input

[Ira_Thorpe]

I have a PCI-6036 which I use to make differential analog voltage measurements using a screw-terminal inerface (SCB-68 with isolated BNC connectors wired to the appropriat terminals).  Although the exact same system has worked flawlessly in the past (card is ~5yrs old or more), it now seems to read +10V on all channels.  My application involves taking data over many hours and ocasionally the card seems to revert to a state where it is reading the correct voltages.  This lasts for maybe ten minutes at which point all channels start reading +10V again.  This is without anyone near the equipment.  I have checked the connections between the BNCs and the card (through screw terminal and cable) and verified that they are correct.  The same behavior occurs with several input sources (shorts, 50-ohm termination, voltage  references).  The +10V readings are also observed in Measurement & Automation explorer test panels.  Any help would be greatly appreciated.

[MickeyD]

Hi,

The first thing to know is which driver you are using, DAQmx or Traditional DAQ.  If you are using DAQmx, have you tried autocalibrating the card in Measurement and Automation Explorer (MAX).  If you do that and see the same beahviour, then we should use the DAQ Diagnostic utility.  This only works if you have DAQmx installed and is located at the following link.  If you are using Traditional DAQ, then use the E series Diagnostic utility linked on this page.  Let me know what kind of report those diagnostics give and we will solve the problem from there.

DAQ Diagnostic Utility

Have a great day,

Michael D
Applications Engineering
National Instruments

Message Edited by MickeyD on 03-28-2007 03:33 PM