09-24-2008 01:00 PM - edited 09-24-2008 01:00 PM
Hi!
I have a set of scripts I have been using on various machines, with various version of Matlab and the data acquisition toolbox and E-series card and always worked (PCI 6052E, PCI 6040E)
I recently had to use them on a system with an M serie DAQ installed (PCI 6221) and I had weird signal: while the singal coming into the BNC of the breakout box is around -6V, the card sometimes displays jumps to 0 for one point, synchroneously on both channels I'm recording, as if the card was missing a point and replacing it with 0. The 'remplacement point' is always the same value, for both channels, and no missing data error is issued.
This happens for both a PCI 6221 and a 6251 I tried with the same configuration, but not with a E serie (PCI MIO 16E1).
This only happens for the M series when I have both an AO and an AI running at the same time.
I'm not trying to push the card over its limit: my acquisition and output rates are 5kHz (max sampling rate is 250kHz, max output even more according to the specs), and the RAM on this computer is 2GB vs 2 AI channels, native type : double, max 75 000 points per channel.
Is there anything I can do to prevent that problem?
Specs of the system:
Hardware:
PCI 6221, breakout box BNC 2110
Computer: Windows XP SP3, 2 GB RAM, Celeron 2.53GHz
Software
Matlab 2008a, Data acquisition toolbow 2.12
Acquistion system:
AI:
2 channels
15 000 to 75 000 sample/channel (same problem in both cases: missed points are random, and mostly at the beggining of the recording when there, for both conditions)
5kHz sampling rate
Hw Trigger on PFI1 (from a digital output on the card)
AO
2 channels
5kHz sampling rate
Hw Trigger on PF6 (from a digital output on the card)
DIO (for the triggering)
1 line output, which output is connected to PF1 and PF6 on the breakout box
The AI is logging and the AO is sending with the following scheme:
start([ai ao]) %%sets AI and Ao Running 'on'
putvalue(dio,1) %Triggers the AI and AO
This works like a charm for E series and synchronizes the input and the output.
Thank you for any help!
Erwin
10-10-2008 09:31 AM
Hi Erwin,
As you discuss it with my working colleague by calling the phone assistance; using LabVIEW, there is no point missing.
I send here the VI my colleague sended to you, in case it would help anyone which might encounter the same kind of problem.
Best Regards,
Flo