saturated signals from bridge attached to SCXI 1121

[slowflyer]

Whilst trying to read the output from a full bridge using a 1321 front panel on a 1121 card in an SCXI 1001 chassis connected to a PCI 6024E when I read the signal all I see is the input fixed at the maximum input voltage (0.005V constant). I have tried attaching a signal generator to another channel (gain 1) and now a constant 5V . For the bridge the gain was set at 1000 with 3.33 V excitation and 10 kHz filter. I have tried the 4Hz filter, different gains settings. I have tried changing the card type from the factory default to rse and nrse on jumper 33. I have tied the negative signals to ground via a 64kO resistor.

I have tried the  1321 and 1121 with the same jumper settings in an SCXI 1000 chassis attched to the 6024E and record the input signals correctly.

I am coming to the conclusion that there is a fault in the SCXI1001 chassis. Does anyone know anything else I might try or does it sound like a fault with the chassis? ( I have tested the two fuses behind the fan at the back and they are OK) If a fault with the chassis any ideas where it might lie?

thanks

[Ashish_Naik_NIUK]

Hi slowflyer,

I would like to clarify some information off you.
What signal are you trying to read initially? Do you have an approximate value this could be aiming for?
Are you getting this reading within MAX? Have you tried

You said you have tried other filters and other gain settings. How did these each in turn affect the reading you are receiving?

Please doublecheck you are using the right pinlayouts within your application. These can be found by Right-click the device name in MAX to see the device pin assignments (pinouts). Pinouts are also in the
Device Terminals in the Measurement & Automation Explorer Help for NI-DAQmx, accessible from
Help»HelpTopics»NI-DAQmx»MAX Help for NI-DAQmx.

Can you confirm that the Chassis and Modules are all recognised properly within MAX?

Have you tried the equipment within any other slot of the chassis?

Have you checked the fuse also within the Main Power Fuse aswell as the Backplane fuses?
http://digital.ni.com/public.nsf/allkb/E8064C591C5FDA1A86256A4D00817C1C?OpenDocument

Please let me know how you get on.

[slowflyer]

Ashish, thanks for looking into this.

What signal are you trying to read initially? I was trying to read the output from a full bridge of 120 ohm strain gauges as I was only expecting microvolt output I had the gain set at 1000 and excitation voltage at 10V. First thing I noticed was that when I connected the bridge to the excitation output the excitation voltage fell from 10V to zero ( I thought this might be a short but checking continuity did not show this) I changed the excitation to 3.33V and this worked but the only signal I see was a fixed 0.005 V

Do you have an approximate value this could be aiming for? reading the bridge output with a dvm showed about 100 micro volts

Are you getting this reading within MAX? yes and in labview

You said you have tried other filters and other gain settings. How did these each in turn affect the reading you are receiving? tried both filter settings with no change to the fioxed 0.005V

Please doublecheck you are using the right pinlayouts within your application. I have trasnferred the bridge, front 1321 module and 1121 to a SCXI 1000 chassis and it works OK

Can you confirm that the Chassis and Modules are all recognised properly within MAX? the Chassis is recognised by max and tests properly

Have you tried the equipment within any other slot of the chassis? Tried different 1121 modules in the chasis and in different slots but with no change

Have you checked the fuse also within the Main Power Fuse aswell as the Backplane fuses? I assume the main fuse is OK as the chassis power light illuminates and the fans operate

If you require any more info please let me know

thanks

[Mark M]

Hi,

If the same setup works fine with a SCXI 1000, this could be a issue with the chassis.  Please contact your local NI representative and they will help you to arrange an RMA.

Also, I suppose you obtained the chassis from the country where you live? If you have obtained the chassis from abroad, they will come with different fuses.

Hope this helps,