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Intermitten problem obtaining data with PXI combo chassis
Sargon
Member
02-03-2003 07:06 AM
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I am having a problem with my PXI-1011 chassis obtaining data in MAX. The problem is outlined below but only seems to happen occasionally and only when I have turned on and off the system or the Backplane. My setup is
PXI-1011 Chassis
6052E DAQ Card
2 x SCXI-1102
2 x SCXI-1102C
1 x SCXI-1163HV
1 x SCXI-1162R
2 x SCXI-1126
1 Third Party Syncro/Resolver Cpci card.
I am running Ni-Daq 6.9.2
The Problem:
I have the problem that intermittently the data coming from the SCXI chassis to MAX is incorrect. It seems to happen often when I am changing any of the hardware. I have not seem the problem once the system is up and running and stays running. There seems to be 2 different symptoms which occur. Either I get no data showing up on any channel or I get data which seems to be less then half of the original value. The second of the two scares me more then the first b/c if someone is not paying attention they could assume the system has started correctly. Now this problem has been seen on 3 different chassis with 3 different card setups on it. The only difference on the one I am working on right now is it seems to happen more often.
The Solution:
I have worked out a way to get the chassis to start reading the data correctly again but I would like an explanation of what is going on with the hardware and how to avoid it from happening. To get the data to start coming in correctly again, often all I have to do is go to ANY card in the device list. Go to properties and change one of the settings (Eg. Gain), hit apply, change it back to were it was before and hit ok. When I do this I hear a faint clicking sound almost like a relay clicking. Most of the time the data starts to read correctly. Sometime if this does not work I need to turn the backplane off and back on again and follow the above step and that will correct the problem. After playing with the various cards in the SCXI slot and determining that the clicking sound is not coming from any of them, I feel the sound comes from the 6052E DAQ card or the chassis. Unfortunately experiments at NI have been unable to reproduce this sound. I think the action which is taken when I change the device information is that the DAQ card resets it's communication with the Bus. My assumption is that somehow the DAQ card is either losing communication with the BUS or is somehow out of sync and is reading the wrong values.
Has anyone seen this problem and know of how I can resolve this issue?
Thank you in advance
Philip
PXI-1011 Chassis
6052E DAQ Card
2 x SCXI-1102
2 x SCXI-1102C
1 x SCXI-1163HV
1 x SCXI-1162R
2 x SCXI-1126
1 Third Party Syncro/Resolver Cpci card.
I am running Ni-Daq 6.9.2
The Problem:
I have the problem that intermittently the data coming from the SCXI chassis to MAX is incorrect. It seems to happen often when I am changing any of the hardware. I have not seem the problem once the system is up and running and stays running. There seems to be 2 different symptoms which occur. Either I get no data showing up on any channel or I get data which seems to be less then half of the original value. The second of the two scares me more then the first b/c if someone is not paying attention they could assume the system has started correctly. Now this problem has been seen on 3 different chassis with 3 different card setups on it. The only difference on the one I am working on right now is it seems to happen more often.
The Solution:
I have worked out a way to get the chassis to start reading the data correctly again but I would like an explanation of what is going on with the hardware and how to avoid it from happening. To get the data to start coming in correctly again, often all I have to do is go to ANY card in the device list. Go to properties and change one of the settings (Eg. Gain), hit apply, change it back to were it was before and hit ok. When I do this I hear a faint clicking sound almost like a relay clicking. Most of the time the data starts to read correctly. Sometime if this does not work I need to turn the backplane off and back on again and follow the above step and that will correct the problem. After playing with the various cards in the SCXI slot and determining that the clicking sound is not coming from any of them, I feel the sound comes from the 6052E DAQ card or the chassis. Unfortunately experiments at NI have been unable to reproduce this sound. I think the action which is taken when I change the device information is that the DAQ card resets it's communication with the Bus. My assumption is that somehow the DAQ card is either losing communication with the BUS or is somehow out of sync and is reading the wrong values.
Has anyone seen this problem and know of how I can resolve this issue?
Thank you in advance
Philip
markwysong
Active Participant
04-09-2003 12:17 PM
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After reading your post again, I'm still a little confused. I'm going to state what I think is going on, and maybe that will clear things up.
I've seen weird things like this before when I've left MAX running on the PC, and then turned off my PXI/SCXI chassis and changed hardware.
When MAX first starts, it sets all the gains/filters that you have set for any cards. If the chassis is turned off and back on, and MAX hasn't been restarted (or a property of that card hasn't been changed), it will assume that all the settings are the same, even though the default state of the card may be different (like a gain setting).
This may explain why you are seeing what you are seeing.
I usually use MAX only to determine that my card is working. If you are using
LabVIEW (or some other programming language), I make it a practice to set the gain and filter settings when I'm setting up the acquisition. That way, I can be assured that NI-DAQ will reset the boards to the proper settings, no matter their default or current state.
I would bet that if you practice this in your code, you will not have these problems you are seeing in MAX.
Also, make it a habit to exit MAX whenever you are changing hardware.
Mark
I've seen weird things like this before when I've left MAX running on the PC, and then turned off my PXI/SCXI chassis and changed hardware.
When MAX first starts, it sets all the gains/filters that you have set for any cards. If the chassis is turned off and back on, and MAX hasn't been restarted (or a property of that card hasn't been changed), it will assume that all the settings are the same, even though the default state of the card may be different (like a gain setting).
This may explain why you are seeing what you are seeing.
I usually use MAX only to determine that my card is working. If you are using
LabVIEW (or some other programming language), I make it a practice to set the gain and filter settings when I'm setting up the acquisition. That way, I can be assured that NI-DAQ will reset the boards to the proper settings, no matter their default or current state.
I would bet that if you practice this in your code, you will not have these problems you are seeing in MAX.
Also, make it a habit to exit MAX whenever you are changing hardware.
Mark
