01-11-2013 10:55 AM
sensor : dev1 ai-9 ( pin 66 ) - ai-1 ( pin 33 ) : differential configuration
resistor : dev2 ai-0 ( pin 68 ) - ai-8 ( pin 34 ) : differential configuration
dev1 ao1 ( pin 55 ) - gnd ( pin 21 ) : RSE configuration
sorry for the circuit diagram, I don't have pspice I just made one on Word quickly to give you an idea. I am writing a sine wave signal on one channel and acquiring it through sensor and resistor which is connected in series. I am also attaching a new block diagram/front panel pic. I did a little change to previous one I sent you, this has stablised the signal a lot but I am still getting an initial jump when the acquisition start.
01-11-2013 12:08 PM
OK, good. I see you modified your code to include the RSE and Differential inputs. That was what I was getting at.
Could u provide the model number for your two PXI cards?
- John
01-11-2013 01:06 PM
Also, I think you need to change the "auto start" input on DAQmx Write to FALSE. Otherwise, the top task (master) won't wait for the bottom tasks (slaves) to be ready.
01-14-2013 01:31 PM
I changed the autostart to false, but it did not affect the graph I am still getting an initial jump. Also when I try to read more than 1000 samples @ 100000samples/secs it takes forever to get a reading. Would you please tell me what I am doing wrong?
I am not sure if this is the model number but this is what is written at the back of pxi chassis, NI-PXIe - 1073 and it is connected to two NI-SCB - 68 M-series connector blocks .
01-14-2013 01:50 PM
Can you upload your actual code? Just upload the .vi that is having problems.
And the model number you are quoting (1073) is still for the chassis. Not for the card. See the picture I upload earlier. The model number for the card is on the front of the chassis ... on the card itself.
01-14-2013 01:53 PM
And I am still confused by what you mean by "an initial jump".
Can you attach another screenshot and highlight the exact error you are seeing.
01-14-2013 01:58 PM
sorry I overlooked the image you sent me. I got the model number : it is NI - PXIe - 6361 and 6221 . Also I am attaching the code, I made a little change I removed the DAQMX write vi after the start and left only one and I noticed there is no change in the graph.
01-14-2013 02:04 PM
I am attaching the front panel image showing the jump I was talking about.
01-14-2013 02:25 PM
please take a look at this code and tell me what you think. I don't want continuous acquisition but I want a consistent waveworm written with no jumps. I am also including the front panel pic.
01-15-2013 07:13 AM
OK. I keep going back to your schematic wiring diagram, because I still suspect this is a wiring/electornics issues ... and not software related. But I am still confused how the wiring is done. Any chance you can elaborate on the schematic? What is that "amplifier" you have specified? How is that connected? A proper schematic will help a lot.
I'm curious if this is NOT an error. But just a natural overshoot? I am a software engineer, so I can't respond to that issue.
On a side note: Why are you using two PXI cards? You can easily accomplish this task with only one card. The way you have programmed it, I don't see the need for two separate cards.