SCC-AI01 modules with SCC-2345 and DAQCard-6062E

[stevenanderson]

Here is the problem as far as I can see right now.  I have a DAQCard-6062E wired to an SCC-2345 backplane with two AI01 modules (along with a couple of other modules) installed.  After working about three months, I began to experience problems with the primary channels (ai0) in each of the AI01 modules - returning readings comparible to white noise and not matching the signal (low voltage output) that was to be acquired (verified with a digital multimeter).   When testing the channels within MAX (they were traditional NI-DAQ virtual channels), the system would lock up, not return to normal functionality and require a hard reboot of the laptop pc.  The several times that this occurred, the traditional NI-DAQ drivers had to be reinstalled in order for the system to operate again (recognize the DAQCard, channels and power the backplane).  Problems persisted with the channels and the board functionality until connecting the sensor (excited through the +5V exciation from the DAQCard) to the bnc connectors on the front of the SCC 2345 would appear to short out the +5V excitation of the entire backplane.  Removing the sensor restored excitation to the backplane (repeat process).  Does this appear to be a malfunctioning AI01 module(s) or could the issue now involve the signal conditioning backplane or the DAQCard itself?  I have remedied the situation temporarily by using the secondary channel on the modules (ai1) and switching backplane slots and everything works now as it did before problems arose. 

[Jesse_O]

Hello Steven,

I have read through your problem, and I do not completely understand.  I see you are having problems with your two SCC-AI01 modules, and that you are seeing noise on these channels; however I do not understand when you see shorting of the +5 V line.

Because you are mentioning shorting the backplane with the +5 V line, I would like to verify a few things.  First, what power option are you using (PWR01, PWR02, or PWR03)?  If you look at the SC-2345 manual, found here, in appendix c, you will see how to determine which power options are available to you.  From what you described the PWR01 modules probably is not possible with the DAQCard 6062.  If you are using the PWR01 option I can see this causing you problems.

Secondly, you mentioned that you are using the +5 V line to power your external sensors.  The +5 V line on the DAQCard has a limited amount of current it can output, and if you are using the PWR01 option it has even less for powering sensors.  If you look in the E Series manual, you will see the + 5 V line is rated for 250mA at 5V.

Drawing too much current (as described above), could be causing your problems.  If you are not drawing too much current can you provide more information on what you mean by "short out the +5 V"?  Also, what happens if you use the first channel on each of the SCC-AO1 modules in the slot they are currently working in?  Do the A01 modules work in any of the analog slots in the SC-2345?  Can you measure another simple analog signal (not related to your sensors or BNC connectors) such as a 1.5V battery?

Finally, if possible, do you see this same noise/crash if you use DAQmx test panels in MAX?

Regards,

Jesse O.
Applications Engineering
National Instruments

[stevenanderson]

I have used the test panels both with the virtual channel test panels and the daq mx test panels on the card itself to verify the voltage readings with the ai0 and ai1 channels in the original slots and the current slots.

When I try to use the modules in the other analog input slots, the ai0 channel does register the voltage from an external signal, just not in the original two slots that I was using, which would lead me to belive that the module is no longer the issue.

I've checked the operation using external voltage sources and they register within the daqmx test panels and the virtual channel test panels.

The power configuration used is the PWR 01 option with power from the daq card.  The current requirements on the sensors are small with one a switch (normally open) with a high resistance in line, one as a 5K variable resistor, and one a low voltage load cell.

During operation as it currently is right now, the indicator lights on the side of the SCC-2345 box (three green lights) are currently lit.  During the time of the problem, before I switched slots on the scc-2345, attaching the sensor to the bnc connectors on the front of the box would result in the three lights going out and the card not recognizable in MAX (essentially hiding the entire signal conditioning and data collection system).

[Logan_K]

When the power lights go out, that indicates a few different possible failures:

1) There could be either a short in your SC-2345 carrier somewhere, or your SCC-AI01 module is damaged.
2) No power (check your connections, and make sure the power switch on the SC-2345 power module is in the appropriate position).
3) Too much power is being drawn off of the 5V line on the 6062e, which could be causing that DAQ board to function improperly.
4) The 6062E power supply is damaged and can't supply adequate power anymore.


Logan K
National Instruments R&D