SCXI calibration

Now I try to using SCXI-1112's built in sensor to measure outside temperature which is measured by thermocouple,through DAQmx I can define the input terminal and sensor terminal in SCXI-1112, I think I have done the sensor calibration, but when the system runs, the temperature drift largely from -20 - 890 degree, it seems it doesn't calibrate. I don't know why it changed so largely? have I completed the cold junction calibration or not? from other documents it seems I need calibrate reference coltage, and so on. please give me suggestion. thanks.
newguy

Hmmm, a temperature drift between -20 - 890 degrees doesn't sound like a calibration issue. Sometimes accidentally scanning the wrong channel which has nothing connected to it will show a reading that drifts like that.
Now I'm a little unclear about how you are trying to measure the outside temperature. Are you trying to read a thermocouple that is connected to the SCXI-1112? Or are you just trying to read the buil-in CJC sensor inside the SCXI-1112?
Since I can't be sure how you have tried to set up the measurement, try following the steps mentioned in the SCXI Quick Start Guide just to be sure it's done correctly. If it's the b
uilt-in CJC sensor you're trying to take readings from, use the channel string mentioned in Knowledge Base 0Z63B4AQ.
I hope this helps!
-Russell
Applications Engineer
National Instruments
http://www.ni.com/support

Similar Messages

SCXI 1125 self calibration

Hi,
Does SCXI 1125 support self calibration? If yes, can I do it using the DAQmx Self Calibrate.vi?
"A VI inside a Class is worth hundreds in the bush"
യവന്‍ പുലിയാണു കേട്ടാ!!!

Thank you Vishal.
SCXI 1125 user manual says that internal calibration is possible (for offset) and that we should use the SCXI calibration VI (not the DAQmx Self calibration VI). I am not able to find this VI in the DAQmx Calibration palette. The only SCXI calibration VI present is for external calibration.
"A VI inside a Class is worth hundreds in the bush"
യവന്‍ പുലിയാണു കേട്ടാ!!!

DAQ 6035-E and SCXI 1122 calibration with VI. Has someone already calibrated such boards through the NI calibration procedures ?

E-Series Calibrate.vi and SCXI Calibrate.vi

There is great documentation in the LabVIEW Help files about how to use the E Series Calibrate.vi for external calibration. For internal calibration: set the task id as the device number, operation as Self Calibrate, and write to the User EEProm area.
There is also a link to the LabVIEW Measurements Manual in the LabVIEW 6 Help documentation for SCXI Calibrate.vi The Measurements Manual covers SCXI calibration in Chapter 9.
Raecine
National Instruments
http://www.ni.com/ask

Calibration of scxi-1112

how do i calibrate Scxi -1112 internally and externally example using fluke instrument.
can i calibrate scxi-1112 using calibration executive.

Suresh,
I assume you will be using LabVIEW to perform the calibration (let me know if I am incorrect). The LabVIEW help for "SCXI Calibrate.vi" (Functions >> Data Acquisition >> Calibration and Configuration) describes its use for both internal and external SCXI calibrations.
Good luck with your application.
Spencer S.

Calibration of scxi-1112 channels simultaneously

can i calibrate all the channels in the module simultaneously using Scxi -calibrate vi if so please send me a example in lab veiw

Suresh,
It is not possible to calibrate all of the channels in the SCXI-1112 module simultaneously. However, it is possible to design a program which will calibrate every channel sequentially without having to manually update the SCXI channel string between each calibration run. Simply place the SCXI Calibrate VI in a for loop. Use the index of the for loop as the channel number and create the channel string dynamically. You can then pass this string, which will change each time around the for loop, into the SCXI calibrate VI.
Regards,
Justin Britten
Applications Engineer
National Instruments

System calibration of TBX-1303 tied to SCXI-1001 Chasis

I'm wanting to calibrate the complete NI system back to the computer by inputing an equivalent temperature millivolt signal thru an ice bath into a TBX-1303 thermocouple card that's tied to a SCXI-1001 chasis. Do the 32 channels on this TBX-1303 card get multiplexed through one D/A or is there one D/A for each channel? I want to know if I can calibrate through one channel or do I need to check each individual channel?
Thanks for your help.
Mike Stair

Mike,
The SCXI chassis and modules do not have an ADC (analog-digital converter) chip. The purpose of SCXI is to condition signals being measured from a sensor (TCs in your case). The module and terminal block do all the necessary conditioning like filtering and amplification, and the SCXI chassis backplane routes the clean signal back to some type of data acquisition card; this card has the ADC chip on it. Typically this card has a multiplexer design. So you would need to calibrate each channel on the SCXI module and terminal block.
Wayne T. | Application Engineer | National Instruments

SCXI-1321 Bad Chips and Function Calls

8-4-04
This message is intended for the PSE of the SCXI-1321 and that person�s manager. Please route it accordingly. I would appreciate a phone response to 8**-2**-2*** so that I might share some specific experiences.
To the managers of the SCXI product line,
I have used the SCXI-1121 with the SCXI 1321 for some time now, approximately 6 years. Our company generally uses them for full bridge pressure transducers and similar applications. I have some suggestions that would make them more saleable. I also believe that you will never know how many customers you have already lost on this product line, for the reasons given below.
1. For many years the shunt resistor on the 1321 has been vastly unusable. What SHOULD be possible is to command the shunt resistor through a Labview command, and then read the virtual channel to see the shunted value. That IS the purpose of the feature. What happens is that once you set the shunt command, then read the virtual channel, the very act of reading the channel UN-shunts the resistor. What you read is some value part way between, because the chip relay from Clare actually ramps open and closed, unlike a mechanical relay. If your timing loop to read the value is consistent, you will consistently read a BAD value. Several VI�s tried to command the shunt, then quickly read the virtual channel, then loop and do it again, and thought they had solved the problem. Further investigation showed that all that was really happening is that the readings appeared to be stable because of the fast loop time, but were actually mid-release of the shunt for all readings.
2. NI eventually starting saying �don�t use virtual channels with the shunt�. In fact, there is a channel string that starts with the word �shunt� that was recommended. The only problem with this is that the data that comes back is not scaled! Keep in mind that NI has been pushing �virtual channels� on users for many years as the way to do business, and so entire test stands are developed around them and MAX. Because we depend on MAX to do the scaling, how are we supposed to be able to read the data scaled? Does NI expect customers to duplicate the efforts of MAX for every virtual channel and scale it separately? Do I have to keep duplicate tracking of scaling information so that my virtual channels will work in the main code, but again elsewhere so that my calibration routine can read the data? This is messy, and for most customers, untenable.
3. I was told, literally, year after year and release after release, that the problem would be fixed in future versions of NI-DAQ. Each release proved that the problem was not resolved. I am sure that many customers were not repeat customers as they found the problems associated with using a simple shunt on the board. I myself needed this hardware due to the 1121/1321 parallel operation capability.
4. After years of trying to fight with the issues above, and what seemed like random problems with the shunting of channels, a second hardware related issue has finally been identified. See SRQ#600753 with Michelle Yagle. The Clare solid state relays installed on the 14 different 1321�s I bought ALL had the same defect. Imagine what this means for troubleshooting! You swap boards to try to troubleshoot, but they are all defective and so you falsely rule out the board, the problem didn�t resolve with a different board. The lot# 0027T12627 of chips covers a wide range of 1321 serial numbers (see my SRQ for details). That means this impacts a lot of potential customers. The part is rated by the manufacturer to 80C, 176F. This particular lot stops functioning as low as 96F! A great deal of testing with heat guns, shop air, and a thermocouple showed that all the chips in this lot fail somewhere between 96 and 110F, well below manufacturers specs or NI�s specs on the board. I also tested lot 98, from a board two years older, as well as new chips from lot 03, which both worked perfectly all the way up to 212F (100C).
Conclusions:
I believe that the people that have tried to use your 1321 have generally had a miserable time of it, unless they already do their own scaling (like some of the Alliance members do.) This is because the shunt feature is not compatible with virtual channels, because NI did not offer a reasonable fix for this problem over a four+ year period, and does NOT advertise this limitation when people are making hardware selections. Further, I believe there are many people that have boards with the same bad lot of chips on them that don�t know it. They may have elected to hardwire their own resistors after fighting with random problems (temperature related). They might have elected to hardwire their own resistors to get around the NI-DAQ limitation. They might not even use the shunt resistor. But one thing is certain: NI needs to clean up this board�s operation, make sure that customers of the serial numbers in my SRQ named above are notified of the bad chips, and fully test that the use of the relays is transparent to LV virtual channels in the future. People will not trust NI products with this type of problems, and will not buy the product again if all the features don�t work!
I have helped NI resolve similar issues with the SCXI-1126 years ago, which had a number of scaling issues in NI-DAQ (the board read great when you used 1k, 2k, 4k, 8k, etc. even ranges, but if you set a virtual channel to 0-2200, the readings were off.) I plotted the problem, documented it with my sales rep, and worked at length with tech support. The boards also had a lot of bad buffer amplifier chips that allowed cross talk between channels, causing a lot of other spurious problems. Those experiences were horribly frustrating, but I now buy the product with confidence. It took a lot of push on my part to convince NI there was a real underlying problem. This 1321 board is similar.
I want NI products to be the best they can be, as I have dedicated my career around them. Please take this feedback to heart, and contact me at 8**-2**-2*** to talk about these issues. Additionally, I am speaking at NI week this year and will be available for discussion. Contact me at the same number.
Sincerely,
Tim Jones
Test Equipment Design Engineer
Space Shuttle Program
Space, Land and Sea Enterprise, Hamilton Sundstrand

Tim
Thank you for your feedback for the SCXI-1321 terminal block.
I wanted to see if it would be possible for you to move your application to NI DAQmx, the new driver for DAQ and SCXI as of NI-DAQ 7.0. I have tested the shunt calibration using a SCXI-1121 and SCXI-1321 and it works as it should. There are two ways to do the shunt calibration with DAQmx.
The first is to use the Calibration feature in the DAQ Assistant. When creating a DAQmx Task in either MAX or LabVIEW, you can select the �Device� tab and click on the Calibration button. It will then ask you if you either want to do a null or shunt calibration, or both. It will then do the calibrations selected and save the values to the task.
The other option to measure the shunted value is to use the AI.B
ridge.ShuntCal.Enable property node in LabVIEW. By setting this property to True, the driver will enable the shunt for the current measurements. If you are taking a strain measurement, the value will be converted to strain.
We are currently looking into the issues you are seeing with the Clare relays to see if other users could be affected.
Brian Lewis
Signal Conditioning PSE
National Instruments

Writing in sensor calibration data to my virtual channels in MAX using Labview.

System consists of a few pxi6713 cards, a 6527 digital input card and some scxi cards (1520, 1104c, 1125).
Every 3months or so we run a calibration on the testing stand which uses these cards, and the sensor ranges and physical ranges listed in MAX has to be manually entered each time.
I am looking for a way to do this automatically. This may be a problem, but we are using NI-DAQ legacy (perhaps if absolutely necessary we could goto daqmx).
I have figured out howto read virtual channel information from max correctly, but I have no understanding of trying to write calibration information to the virtual channels.
Any help is greatly appreciated!
Thank you!
jacob

Hi mak90,
There are no ways to change the sensor range and physical ranges
programmatically in Traditional DAQ. Under DAQmx, you have Scaling VIs,
Calibration VIs, Task VIs that allow you to change various settings in
MAX programmatically.
Please let us know if you have any further questions.
Best regards,
Nathan Yang
Applications Engineer
National Instruments

Calibrating a 6552 using Cal Exec.

I am trying to calibrate a 6552 card.
What does Cal Exec mean when its asking me to "Select the switch device strings" "SCXI slot 0" and "SCXI slot 1"?
I have never seen this before?

Hi,
The "Switch in SCXI Slot 0" and "Switch in SCXI Slot 1" string entries show up in Calibration Executive's DUT Selection configuration window when NI 6551/6552 cards are being calibrated. They expect a string in the DAQmx format (e.g. dev0) and it should be the Device ID of the Switch.
NI SCXI-1193 cards are needed for this calibration setup.
More information can be found on the help file of the Calibration Executive under "Calibration Executive Help - Device Calibration Procedures - Modular Instruments - HighSpeed Digital - NI 6551/6552 Calibration Procedure"
Best Regards,
Mark N
Applications Engineer
National Instruments UK & Ireland

How do I deal with a cascaded system, First Stage SCXI-1520's and Second Stage SCXI-1143's?

I am aware of the following link:
http://digital.ni.com/public.nsf/allkb/653505DF63AD04E686256DD7005D42F6
I'm kind of stuck here. The system is already in place. 1520's in first stage and 1143's in second. I am supposed to configure the 1520's and scan the 1143's.
What problems do you see with this?
How do I go about doing an end to end calibration?
Should I just rip out the 1143's and hope nobody notices?

Hello Frank,
Let's start from the beginning. I understand that you have some SCXI-1520s and 1143s that you are using in your measurement system. What type of sensors are you acquiring data from? It seems that you intend to use the 1143s to filter the data between the 1520s and the software. Is this correct? Another question that I have is what do you mean by "end to end calibration?" The more specific that you are about the application you are developing, the easier it will be for others to help you with any questions that you might have.
Looking at the knowledge base article that you linked in your original post, it seems that the point was to filter the data from the SCXI-1520 in software, using the LabVIEW Filter Express VI. Would this be a viable option for you? If so, then you could just rip out the 1143s.
Regards,
Wallace F.
National Instruments
Applications Engineer

What is the combined effect of the SCXI-1520 Gain and NI-Max Gain?

LabVIEW 6.1
SCXI-1000
SCXI-1520
SCXI-1314
PCI-6031E
Windows 2000
Greetings-
I'm trying to determine how the gain that is settable on a given channel of an SCXI-1520 module is combined with the gain that NI Max assigns to a Virtual Channel.
For example, if you set a gain of 100 on ch0 of an SCXI-1520, and you then create a Virtual Channel to read the mV output of the Ch0 sensor, (in this case a full bridge load cell), should the AI limits (range) that you specify in the Virtual Channel creation reflect the gain of 100 that the 1520 module is already applying to the signal? And after the 1520 module applies it's gain, does NI Max attempt to apply another gain if there is still capacity to amplify the signal within the AI range of the daq device?
Also, when measuring a full bridge sensor as an analog input voltage signal, and after performing a Null on the sensor, there is usually some residual offset. Does one then programmatically (in LabVIEW) tare, or zero this residual offset by subtracting its value from all subsequent measurements?
Thanks for your help.

Hello Steve,
How are you applying gain if not through a virtual channel?
When you set the input signal ranges in MAX for your virtual channel, SCXI and DAQ board gains are applied. For example, if you create a voltage channel to read the mV output of a sensor, and set the range to +/- 10mV, the SCXI Module would apply a gain of 1000 to the signal and send the resulting +/-10V to the MIO DAQ device. The DAQ device will then attenuate this signal to +/-5V (the range of the ADC) by applying a gain of 0.5. Now, if you set the input signal range to +/-1mV, the SCXI Module will apply its maximum gain of 1000 and send the resulting +/-1V to the MIO device. The DAQ device will then amplify this signal to +/-5V by applying a gain of 5.
If you are still seeing a residual offset after null calibration, you should use the Auto Zero property. This property measures ground before an acquisition and then subtracts that value from every subsequent measurement. You can set this in a strain task, or with a Channel Property Node in LabVIEW.
Let me know if you have any further questions.
Sean C.

Problems with the SCXI-1126 Frequency Module

I am finding that, at least my modules, are not responding according to the specifications. I on all channels have not been able to get full range that I set at 0-8kz 1hz filter with a 100mv pp ac signal coming in. The spec shows a 50mv signal for all ranges down to 15hz. Alot of channels have been losing signal at > 200hz sometimes as high as 1khz.
I have tried 3 different modules and 3 difference sxci-1000 chasis on two different daq cards. All channels where configured for 0 to 8kz at 1hz filter. I am using a calibrated HP 33120A Function generator to test the channels. I am running out of things to try to get them to work properly.

I am taking these measurments using the measurment and automation explorer test function. I set my range on all channels to 0-8khz and Have been inputing no more than 8khz. What leads me to believe I have a software or config problem is that I sent in a module to NI for repair and this is the brand new one they sent me back. While testing this module, I also have a 1102 module and 1124 module on the scxi-1000 chasis and both of those are working as specified. I also moved the 1126 module to slot 1 and ran it that way as well when I replaced the chasis.

SCXI 1520 quarter bridge setup will not output excitation voltage, but full bridge will

My SCXI system will not output an excitation voltage to the quarter bridge(verified with voltmeter). It works for a full bridge setup. When connected to a 'quarter bridge I' configuration, I can use MAX to null and shunt calibrate. The quarter bridge circuit appears to be balanced after the calibration, but the calibration results post a software gain factor close to zero, as well as a close to zero excitation voltage (eventhough I have the voltage configured for 5 volts). I have the SCXI 1520 module, the virtual channels, and the wiring properly configured (several years experience with this device). I'm using an old E series DAQ card AI-16XE-50, with the 50 pin cable that plugs in the back of the SCXI chassis. I noticed I had two bent pins with the cable connector module that plugs into the SCXI backplane. I was able to straighten them, so the cable connects properly, but I suspect the bent pin incident caused electrical circuit damage. Any suggestions on trouble shooting? None of the three 1520 modules I have will output an excitation voltage for a quarter bridge.

Sorry that I don't have an answer for you tyea, but I'm interested in your thread because I have a similar issue with a 1520. My excitation votltage, as measured with a DVM, is always 1V. I've tried 0V, 1V, 5V --- it's always 1V, on Full or Quarter bridge. I'm using a similar DAQ to yours - a PCI 16XE-10 (and a PCI-6030E on antother system).
I don't have a lot of experience with these modules. This could be a wiring or programmatic thing I'm doing wrong.
Richard

Calibration Management Software

I work at a research lab that has approximately 7 test cells. Each cell has around 50 measurement channels using field point or PXI/SCXI DAQ read by Labview. Hooked up to those channels are TC's, pressure transducers, flow meters, level sensors. We have some in-house calibration equipment (PRTD's with dry well's, high accuracy pressure sensors with pressure sources). In the past calibration was done by comparing the readouts of the calibration equipment with the readouts of the Labview screen by typing the information into Excel, generating curve fits in Excel, and then typing the data into Labview (or maybe even reading a file in Labview) and then the calibration equations are run in the Labview program. The different calibration points (say 70 oF, then 80 oF) have been set manually by a person watching the operation. I have gone through and used Labview to automate reading the calibration sensor and changing the setpoint on the source (dry well). This is a great accuracy improvement and time saver. The next logical step is to keep the calibration history in a database so that we can evaluate drift over time, etc., instead of decentralized Excel sheets for each channel. We have found many companies that make "Calibration Management Software" (CMS), though none that do not require extra customization so that I can take the data from my automated Labview Calibration routine and enter it pragmatically into the CMS, and then pragmatically recall calibration coefficients from the CMS. At my previous employer I saw a software package have this sort of communication with MetCal/Trak, though in talking with the fluke sales man he started talking of extra licensing fees, paying them to write specialized code, etc. beyond just paying for the MetCAL/Trak. The added cost to get the Labview integration was left an undefined number.
Does anyone have a good solution that they use that they could share some details on?

Hey James,
Sadly, I'm not familiar with any calibration management software that does not require added customization. When you say that you have the calibration history in "decentralized Excel sheets", what exactly do you mean? My thinking is that you can develop your own CMS using the file writing/reading in LabVIEW. If that's not feasible, it seems like you may have to look more into the customized CMS option.
Hope you have a good one!
Tim A.
National Instruments

Settling time on SCXI-1102C modules

Here's my latest problem in my NI-DAQ saga:
I can't acquire accurate measurements from any of my 1102C modules, with a settling time less than 5us. The documentation on the 1102C indicates that a 3us settling time gives you 0.012% error - which would be more than enough for my application.
What other conditions must be met to acheive the 0.012% error?
The problem is worse when reading channels next to open ones - the open channels float to full-scale, and the channel that actually has a tranducer plugged in is very noisy if it registers any change in voltage at all.
At a 3.125us settling time, the transducer doesn't register, at 4us it's noisy, and at 5us the signal is clean.
Other than providing appro.
termination for all the open channels, is there anything that can be done to improve the settling time?
The 1102 modules are even worse, but since they're thermocouple modules, I can scan them at a slow rate and no one will care.

You can find some good resources at the http://www.ni.com/support pages when you search "settling time and scxi scan". You are correct that you want to ground out the open channels, since floating channels don't have any meaningful data anyway. The KnowledgeBase entries give more description on that. Also, the Developer Zone tutorial shows some tests you can apply to your DAQ board to determine its settling time. Also, I don't know if it will make a significant difference in your situation, but for accuracy in general, you want to make sure your board has been calibrated within the past year. You can look at the http://www.ni.com/calibration pages for more information. If you have an extremely high precision voltage source and DMM, you can even manually calibra
te the 1102 module, as it has an EEPROM.
KnowledgeBase 0HH79DRV: "I See the Same Signal on Several Channels when Scanning, Especially when No Signal is Connected to Those Channels"
KnowledgeBase 28MF7JQO: "Data Acquisition: Troubleshooting Unexpected Voltages or Crosstalk in Analog Input Channels"
NI Developer Zone tutorial "Is Your Data Inaccurate Because of Instrumentation Amplifier Settling Time?"
Regards,
Geneva L.
Applications Engineer
National Instruments

SCXI calibration

Similar Messages

Maybe you are looking for