Input terminal configuration: error -200077: differential mode is only mode possible ?

[CharlesDel]

Hi.

I'm trying to make analog acquisitions with 6124 DAQ cards through a

rack mounted BNC 2090 interface.

The BNC 2090 front panel has different switches allowing to select RSE/NRSE/Differential mode.

Terminal configuration can also be set via soft.
But when configuring RSE or NRSE  in the soft through input 'terminal configuration' of the

DAQmx create channel VI ( not knowing what is default mode dor 6124, not listed in the

NI default modes definition list), error -200077 ( see below) appears , saying only differential mode is

availalable with this configuration (physical channels 'Slot2  0-1-2, Slot3  0-1-2, Slot4  0-1-2' are selected).

Can sby tell me If I ve misconfigured something or if only differential acquisition is available with those DAQ cards ? Meaning only 4 of the inputs would be available for  RSE acquisition insteadof 8 as opposed to what I understood (possibly misunderstood) from the manual ?

Thank you in advance for yor answer.

Regards.

Charles.

Error -200077:

Property Node DAQmx Channel (arg 1) in Waiting_for_trigger V1.13-Charles.vi->MAIN.vi->EMC inspection.vi <append>
<B>Property: </B>AI.TermCfg
<B>Requested Value: </B>RSE
<B>Possible Values: </B>Differential
<B>Channel Name: </B>Voie Analog0

<B>Task Name: </B>_unnamedTask<8E>

[Alexander_Sobolev]

Yes, PXIe-6124 is simultaneos sampling, it has dedicated ADC for each channel and does not have multiplexor to connect channels one after one. So it is 4 differential channels only.

[CharlesDel]

Thank you.

I believe that.

However RSE to my understanding is meant to be able to use the 8 inputs needed

for those 4 differential pairs, as a single RSE acquisition only needs one individual

+ input and a common input for the negative input ( = ground ).

My issue isn't really about acquiring 8 different inputs instead of 4 , but rather to know where the negative input is headed to ( AI8 or common ground, according to whether soft mode is resp. DIFF or RSE ) on the DAQ when selecting RSE on the BNC 2090 front panel, because that makes a difference in whether I need a short circuiting cap or not on AI8, to measure any signal on AI1.

Regards.

Thank you.

Charles.

[RavensFan]

As you've been told, the 6124 does not have a referenced single ended mode on it.  It is only differential pairs.  There is no AI8 or common grouind.

Read the spec. sheet  http://www.ni.com/pdf/manuals/372526b.pdf

and the manual http://www.ni.com/pdf/manuals/372613a.pdf

to learn how to use it.

[Alexander_Sobolev]

Also check the BNC-2090 manual, it explains connections, switches, jumpers, bias resistors for all modes

BNC-2090 User Manual  http://www.ni.com/pdf/manuals/321183a.pdf

[CharlesDel]

Thank you for reply and manuals. I now take for granted the cards do not have any RSE feature.
Only the BNC 2090 has.

I did already have those manuals and as already had gone through them.

AI8 is the input paired with input AI0 on the BNC front panel.

Those manuals (even the BNC 2090's one) don't tell about the necessity of adding short circuiting caps in order to measure any signal at all in RSE mode. However this seems to be the case after a check measurement and I can't imagine another way to do such measurement if indeed no common groud input  is provided on the NI6124.

-Is that so ?

-Is there any information, except its short description in the Labview help , about how pseudodifferential mode works ? For example where to fin the Z+ and Z- impedance values ?

Thank you !

Regards.

Charles.

[CharlesDel]

Default acquisition mode on DAQ NI 6124 card ?

Hi dear all,

I was taking for granted the answer above ( ‘NI 6124 works uniquely in differential mode’)

but recently was confused while observing important ( > 40dB on some frequencies + different spectral shape) differences observed in

signals acquired in both ‘differential’ and ‘default’ mode.

That mode was changed via input ‘terminal configuration’ on the DAQmx ‘Create channel’ VI,

while configuration on the BNC 2090 rack interface was kept constant (SE + RSE on all analog inputs ).

Can anybody tell where this difference could come from and what type of input configuration is used when ‘default’ mode

is set ?

NI 6124 DAQ card wasn’t listed when considering a NI table describing all default modes vs. DAQ card type, found in Labview help, thus am lost.

Thanks in advance for your nice answers !

Regards.

Charles.