Problem:Using same device to measure two AI with two trigger signal

[Dickson]

I am doing a project which using a s-series PXI 6143 to measure 2 AI signal with two trigger signal.

When it receive a trigger signal, the device need to continuate read the voltage for 3.5s.

The problem is that when the device starting reading one of the channel,the other channel can not be triggered and will be received a error signal 50103.

How can i slove this problem except using two PXI 6143?

[Sean_C.]

Hello Dickson,

Thank you for contacting National Instruments.

The error you are receiving (-50103) indicates that the resource is in use. This is because you cannot have 2 analog input (AI) tasks running simultaneously on the same board. You will have to configure both AI channels in the same task. This means that you cannot have individual triggers for each channel.

To use 2 different triggers, you will have to have 2 different DAQ boards. Please see the following Knowledge Base for more information: http://digital.ni.com/public.nsf/websearch/34E4437A050F03F886256F3C00649A42?OpenDocument

Let me know if you have any further questions.

Sincerely,

Sean C
Applications Engineer

[Dickson]

Dear Sean C,
Thank you for your reply.

But because of the limit of the money, we can only buy one DAQ boards for our testing.

Anyway, Thank you for your information.

Regard
Dickson

[Jack_A.]

Dickson -

Sean is correct that there is only one digital trigger available at a time on the 6143. But there might be another way that you can get similar results. Since you are only using 2 of the 8 analog input channels of the 6143, you could tie in the digital triggers for each channel into two of the available analog inputs. Then in software, you can implement a digital trigger on those lines. This adds some software complexity, but allows you to associate a digital trigger with each of you analog signals.

There are several ways that you could implement this. In the simplest case, you could just acquire on all four channels for a set amount of time while saving the data to disk and then through post processing, go back through and find the point where the digital trigger occurred and parse the corresponding analog data appropriately. Another option would be to still acquire data continuously on all channels, but monitor the "digital" lines for a trigger. Whenever the trigger occurs, begin saving that channel's data to disk.

Just some ideas. Hope they help.
-Jack

[rpursley8]

Are you two triggers completely independent of each other or are you just trying to delay one acqusition a fixed amount of time?

[Saloutios]

Hello everyone,

I am facing a similar problem as the one described in this thread thus I decided posting my question here. 

I am acquiring data from 4 analog inputs ai0:3 ( voltage ) in a continuous mode, display the data  (charts and graphs) and stream the data to TDMS files in a consumer loop.

The same time I want to have the ability to save '' time windows'' of my acquisition. For example, I wanna be probing ai1:2 and when the voltage exceeds a certain value , i.e 0.5V, I can trigger with an analog reference and get a certain amount of samples (finite samples) after the trigger and before that ( pre- trigger samples). I am aware of how I can achieve that, a NI example is most helpful : http://sine.ni.com/devzone/cda/epd/p/id/4840 .

The problem is this : I do not want to stop the continuous acquisition which is already undergoing. If I try to start a new task ( somehow '' copy & paste '' the example) I get , as expected,  error -50103, "specified resource is reserved".

So, is there any way of achieving this task without having to bump into this resources reserving problem? And if there is not a way could you suggest a way to perform this pre-trigger and trigger sampling?

Please, find attached a snapshot of the code. I am using a PCI-6254 with two SCB-68.

Thank you very much and looking forward for you advice!!

Best regards,

Panos