Getting eronoeus readings on SCXI 1102

I have a pci-mio-16e-1 daq board and a scxi 1001 chassis a scxi 1102 card and a tbx 1303terminal block. I am reading a temperature of 167 deg f with this system but it should be 202 according to 2 other calibrated instruments. What could be the problem?

Joey,
Since you are posing the question in this group, we have to assume that you are using LV to do this.
Are you using the example VIs such as
found in the Help->Search Examples->Data Acquisition (DAQ)->SCXI->SCXI-1102/1127/1101 Thermocouple.vi. (Or if you have the same essential VIs).
If you haven't, take a look at that example.
I have essentially the same hardware as you describe, except I'm using a PXI-6052e (multi-IO).
Either way, there are a couple of things that you can check on.
As Bruce said, make sure that you select the correct TC type for the conversion.
If you wrote your own VI(s) are you adding the temperature reference??
The example shows how to do this.
(If you are using an external reference such as an ice bath th
ermocouple
[of the same type, of course] in the circuit, then that is taken care of.)
If you are using the CJC in the 1303, you have to set the CJC type to "Thermistor"
Make sure that you are reading the correct channel. eg the first channel is 0...
Make sure that you set the input range (gains) to the correct range.
If you wrote your own VIs from scratch, you may want to run the example VI that I
mentioned above, and see if you get the same results from that.
Dave
"Joey Wood" wrote in message news:[email protected]..
> I have a pci-mio-16e-1 daq board and a scxi 1001 chassis a scxi 1102
> card and a tbx 1303terminal block. I am reading a temperature of 167
> deg f with this system but it should be 202 according to 2 other
> calibrated instruments. What could be the problem?

Similar Messages

Still getting eronoeus readings from scxi 1102

Tried everthing you guys have suggested but nothing so far. My ambient is 49 Degrees F and should be 90degrees F. My bearing Temp is 127 deg F and should be 180 deg F . What else could be wrong??

There are several minor things that could be wrong that would affect your reading. Things from incorrectly specifying CJC, programmatically using an incompatible thermocouple (ex. using a J type but software thinks else). There is an application note (76) entitled "How to use thermocouples with an SCXI-1102 Module" which may be benificial to read through. You can find it at http://www.ni.com/pdf/instrupd/appnotes/an076.pdf
There are several other Application Notes related to temperature measurements available online from http://www.ni.com . I would suggest reading through the developer zone (http://zone.ni.com) and other application notes (http://www.ni.com/appnotes.nsf/) as well.

I Am Getting Inaccurate Readings When Some Channels of the SCXI-1520/SCXI-1314 Are Open Circuits

Am Getting Inaccurate Readings When Some Channels of the SCXI-1520/SCXI-1314 Are Open Circuits
My hardware is :-
PCI MIO 16E-1 - 1 no.
SCXI-1000 chassis - 1 no.
SCXI-1520 - 4 nos.
SCXI-1314 - 4 nos.
MAX is showing all hardware ( DAQ card + Chassis + SCXIs), set in Multiplexer mode.
I am using MAX task to configure channels ( as per requirement ) and then use the same task in Labview 7.1
When I am trying to generate task only for connected channels then reading are coming some times....... but when i generate task for all channels including (not connected channels) then the reading are either on - side or on + side (max or min).
I have tried to ground the +S but not work
tell me some solution
Thanks
Surender Kumar

No, DAQmx is superior and I strongly recommend you used DAQmx
Elijah, I guess I understood the problem that Sunder is facing, coz even I had experienced it 2 years back
What happens is if you scan only the channels to which sensors/strain gauges are connected, all is fine and you get good strain readings.
But if you happen to include an unconnected channel into the scan list, all the subsequent channels after the open channel will show saturated readings.
Right, Surender??
The problem we found, lies in the settling time of the E series DAQ card's ADC. Even we were using PXI 6071 E
Once the ADC saturates on reading an open channel, it cannot settle fast enough to read the next channel.Hence, the next channel also reads saturated value, instead of the correct value.
This is irrespective of the sampling rate because, this happened even when we did continuous sampling at low scan rates of 10 to 100 samples /sec
We found 2 solutions to this problem
Disable Simultaneous sampling and hold for the SCXI 1520 module ( using a DAQmx property node)
Use a M series DAQcard, which did not have this settling time problem
Hope this helps,
Regards,
Dev

Bad reading of thermocouple on SCXI-1102

Hi,
Some of the thermocouple plugged in the SCXI-1102 give bad reading(unusual value). There is maybe an issue with the use of grounded and non-grounded thermocouple? Is the system need to be calibrated?
Thanks.

Hello gperron,
When you say some thermocouples give bad values, does this mean that you have some that give the correct value? If so, try switching the ones that give you a correct reading with the ones that are giving a bad reading. If the bad readings follow the thermocouples, you can conclude that those thermocouples are bad. Are you using the built-in cold junction compensation on the SCXI-1303 to make sure you are getting the most accurate readings?
In general, thermocouples are floating sources and you measure them differentially with a bias resistor connected between the negative terminal and ground. Page 3-4 of the 1102 User Manual describes connecting signals to the 1102. The 1303 Installation Guide describes how to replace bias resistors, if needed.
Thanks,
Laura

SCXI 1001, SCXI-1102 and SCXI-1303 not working correctly with DAQmx

I have recently upgraded from Labview 6.5 to Labview 8.2 and now my SCXI 1001 with a SCXI 1102 and SCXI 1303 terminal block no longer reads the correct voltage. Using the old version of labview thermocouple measurements are correct at 0.5mV; however using the new version of labview and DAQmx the thermocouples are reading 5V. Everything is installed correctly as it still works with the older version of Labview, is there something that needs to be reset or change so that teh SCXI will function properly with DAQmx?

Hello ilabtech,
From my understanding you are using an SCXI 1001 chassis with an SCXI 1102 and 1303 terminal block to perform thermocouple measurements. You are upgrading to LabVIEW 8.2 and DAQmx. I am assuming you were using LabVIEW 6.1 since there isn’t a LabVIEW 6.5. You mentioned that are able to get a correct reading of 0.5 mV with LabVIEW 6.1 but you see a rail of 5V with LabVIEW 8.2 and DAQmx.
My first suggestion is that you ensure that the SCXI is set at the appropriate range and for the correct thermocouple type. You can also configure these settings in MAX as detailed on page 27 of the SCXI 1102 User Manual and Specifications Guide.
My second suggestion is for you to start off using an example program to see if you see the same error. When you are in a LabVIEW 8.2 VI you can go to Help>>Find Examples to open the NI Example Finder. You then choose Hardware Input and Output>>DAQmx>>Analog Measurements>>Temperature>> Cont. Acq Thermocouple Samples-Int CLK.vi.   This example program is supported by your hardware and is a good resource to use to troubleshoot.
If these suggestions aren't helpful please answer the following questions in your reply.
1.       I would like to know what range you have set the SCXI 1102 to read.
2.       What version of DAQmx are you using? You can find the version my opening Measurement and Automation explorer (MAX), expanding the “Software “and clicking on NI-DAQmx.
3.       What operating system are you using?
4. Does your Traditional DAQ program work in LabVIEW 8.2?
Regards,
Ima
Applications Engineer
National Instruments
LabVIEW Introduction Course - Six Hours
Getting Started with NI-DAQmx

Scan order and empty channels for SCXI-1102

Hello-
Sorry for the cross-board re-post, but I really need to get this answered asap.
I have two SCXI-1102 cards in my chassis, all measurements will be routed to ch0 of the PXI-6229 that is also in the chassis. For design reasons, I prefer to use about 2/3 of each 1102, and thus leaving about 1/3 of each 1102 empty.
Should I populate the channels in any particular order? Eg should I start at ch0 or ch31, and which direction is the scan order? e.g. 1102a/ch0 -> 1102a/ch15 and then 1102b/ch0 -> 1102b/ch15 OR say 1102a/ch15 -> 1102/ch0 and then 1102b/ch15 -> 1102b/ch0
Does this matter AT ALL with a PXI/SCXI system? I know with many DAQ devices (E-series for example) you must scan in descending order (eg. 7,6,5...0) so it makes more sense to start populating the last channel first and then leave the lower-numbers empty.
thanks-
brad

Please see this post.
Regards,
Natasa

How can I set the gain on a SCXI-1102 module without having my computer lock-up for 3 seconds?

Forgive my insolence, but did it never occur to anyone that spinning in a hard loop while polling a status register to set a gain for 3 seconds isn�t a great idea?
I have a number of SCXI-1102 modules to set the gains on, and it takes several seconds for each. Reading the documentation on the subject indicates that the SCXI_Set_Gain call polls a status register waiting for the gain to settle before returning � and it doesn�t even yield while doing so.
Are there any other ways I can set the gain? Is there a way that doesn't poll the register that returns in a reasonable amount of time?
AFAICT, there's no good reason to only allow one module to be s
etting its gain at a time. An asynchronous call it really needed - one that makes it the API programmer's responsibility to check the status of the register, or one that spawns a thread and sleeps between polls, and signals an event or invokes a callback or some-such-thing. Or you could even just sleep for three seconds after setting all the gains, this way the delay would be 3 seconds total � not 3 seconds for each gain set.

This NI-DAQ function call directly accesses the nidaq32.dll. While the nidaq32.dll is multithread safe, it is not a multithreaded DLL. This is also described in the KnowledgeBase entry 1V9DSHDM: "Can NI-DAQ Handle Different Operations at the Same Time? Is It a Multi-threaded DLL?"
You are correct that the SCXI_Set_Gain function is not asynchronous. Thus, you do have to wait till that function returns before calling the next one. LabVIEW has found a way around this. So, you can actually use the LabVIEW functions to set the gain on these modules without having to wait as you do with SCXI_Set_Gain.
Regards,
Geneva L.
Applications Engineer
National Instruments
http://www.ni.com/ask

Multiple tc types on one scxi 1102

Does anybody know if you can use two different thermocouple types on one SCXI-1102 module?
I need to measure both Type K and Type T thermocouples. I am using a SCXI 1303 connector block and plan to use the internal CJC.
Thanks in advance
doloop

Hello doloop,
You can indeed configure a task to have to two different types of
thermocouples, and acquire from multiple thermocouple types in one
DAQmx Task. For each channel, the NI-DAQmx driver will apply
different conversion coefficients to convert voltage measurements from
different thermocouple types into temperature measurements. You
can configure this easily in Measurement & Automation Explorer
(MAX), by creating a DAQmx Task of the thermocouple type, and adding
multiple physical channels from the SCXI 1102 module to the channel
list. For each channel in the scan list, under the settings tab,
you will have the option to select what type of thermocouple to
associate with each channel, along with CJC settings. You can
also do this programmatically in LabVIEW using the DAQmx Create Channel
VI. I've attached a shot of a block diagram that shows how to
program this.
I hope this helps!
Travis G.
Applications Engineering
Message Edited by Travis G. on 04-18-2006 05:09 PM
Attachments:
MultipleThermocoupleTask.Jpg ‏68 KB

Where is the SCXI-1102 Register-Level Programming Manual

The SCXI-1102 User Manual refers (in Chapter 5) to a "SCXI-1102 Register-Level Programming Manual". I can't find the register-level programming manual on www.ni.com. Where can I obtain this manual?

Hey Don,
Thank you for contacting National Instruments.
There is not a register-level programming manual for the SCXI-1102. This was a mistake made in the first version January 1996 of the SCXI-1102 manual. This was corrected in the later August of 1997 version.
http://www.ni.com/pdf/manuals/320975b.pdf
Register-level programming is not formally supported by National Instruments. If you would like more information about alternative methods of programming other than NI-DAQ please contact your sales representative.
Best Regards,
Joshua P.
Application Engineering
National Instruments

Cannot configure SCXI 1102 in parrallel mode

Hi all...
I have a little problem, i have a system made of 3 Daqmx cards : 2 PXI-6254 and 1 PXI-6229. these cards are linked to SCXI modules. The acquisition of the data are done in parrell i.e. the first PXI 6254 is linked to 2 SCXI-1125, the 2nde PXI-6254 is linked to one SCXI 1125 and one SCXI 1102B and the third one is linked to one SCXI 1180 and one SCXI 1102...
So i defined 3 different Daqmx Task in MAX (one for each DAQmx card) and i configured the SCXI rack.. but when i try to configure the SCXI 1102 B or the SCXI 1102 i CAN'T choose the parrallel mode i can only choose multiplexed mode... and therefore, when i run my application, i have the following error:
Error -200619 occurred at DAQmx Start Task.vi:6
Possible reason(s):
Measurements: Chassis cannot be used for more than one scanning operation at the same time.
Do only one scanning operation, or combine multiple scanning operations into a single operation.
Can't anybody explain me why ???
Thanks a lot for your futures answers ...

Not necssarily, You can have parallel mode for other SCXI modules while acquiring from SCXI 1102 in multiplexed mode
See this Link

Connection of the pressure transmitter to the scxi-1102 module

Dear sir,
we have a differential pressure transmitter whose specifications are as follows:
Excitation:24 Vdc, output:4-20mA.(make: Cole-parmer instrumentation company)
now, we have a NI scxi-1102 and scxi-1520 module with corresponding terminal blocks.
Our question is how to connect this transmitter to the module and to which module? can we connect it to the scxi-1102? And for the excitation what we should do? please explain the detailed procedure for that.
As the excitation is 24 Vdc, i think we have to use 1102 and has to be excited externally.
Since, i m a mechanical engineer and don't have much knowledge of electronics, please explain all the details as simply as possible.
regards...
Lalit.

I am assuming a couple of things here. They are:
The input you are looking at is a slow responding signal ie less than 2 hz. The 1102 has a built in 2 hz filter.
and or the transducer you are connecting to has a slow update rate.
You are using scxi 1300, 1303, or 1308 terminal block to connect to your chassis.
Channel 0 isn't being used.
That being said, in Max, set the gain to 1
input mode to differential
You can do the scaling in Max if you want to.That's what I typically do.
Linear scAle, 1 volt = 4 ma and 5 volt = 20 ma
On your terminal block, connect a 250 ohm precision resistor across Ch 0 in ( pin 96 & 64)
In series with your current loop ( cut the wire of the existing loop)
Connect one end to pin 96 and the other to pin 64.
Put a voltmeter across the input. red lead to 96, black lead to 64
If the reading is negative flip flop the wires. If positive, good guess.
you should be ready to rock and roll.
GB
Greg Bush CLAD

SCXI-1102/SCXI-1303 not detected in SCXI-1000 chassis

I am using a setup with SCXI-1303 module in a SCXI-1102 within a SCXI-1000 chassis to take voltage and thermocouple measurements.
Until recently, everything was working fine. but it now appears I am unable to communicate with the interface. I have tried two different computers and the hardware is not detected in MAX. The power light and fan on the SCXI-1000 still comes on, there just appears to be no acknowledgment of the connection to the computer.
A few more specific error codes:
* When I double-clicked the DAQ Assistant in the block diagram window and clicked "Test" on one of my inputs, I received the following error:
"Error -88705:The specified device is not present or is not active in the system."
* I have also gotten the error code "Error -89130: Device not available in NI-DAQmx" in the DAQ Assistant test panel
* When closing the DAQ Assistant test panel, I see the error "Error -89130: Device not available for routing"
* In MAX, if I try to "test" the chassis or module, I have seen errors either saying that the device is not detected, or that the device needs to be reset or is in the process of being reset, or that Traditional DAQ drivers need to be reset (I've tried these reset suggestions with no result)
At this point I'm wondering if the board or the cable is shot. I unfortunately don't have another 68-pin cable to test at the moment.
Thanks in advance...
Solved!
Go to Solution.

mtd12 wrote:
Thanks guys, I was able to resolve the problem. For anyone who might come across this,
* I noticed in Windows Device Manager that two PCI devices were listed as not being installed properly.
* After trying to update the drivers, I couldn't start the computer; got BSOD after BIOS load.
* Some research prompted me to pull out the two PCI cards that I was not using, and I also moved my DAQ card to another slot to force a hardware reinstall.
* Booted up, loaded the drivers automatically, and off I went.
Doesn't explain why it didn't work in the other computer, but in the words of Spinal Tap, the authorities said it was better left unsolved at this point.
You should move the DAQ board back and verify whether it still works. Perhaps one of the slots went bad.
You didn't notice that you had two PCI devices that were not installed properly before?

MV/psi input for SCXI-1102 using SCXI-1308?

Is there a way to physically connect a mV/psi signal to an SCXI-1102 that is also using a SCXI-1308 terminal block? From what I have read, the terminal block can only use a 4-20 or 0-20mA signal, right? I don't see any pins that the terminal block doesn't plug in to to use for the pressure sensor's mV output.
Thank you for the help!
tq
Solved!
Go to Solution.

Hi FMC_Pumptest,
The 1308 terminal block is designed for current input. You are right that with that terminal block you will only have inputs for 0-20 mA and 4-20 mA signals.
Regards,
James D.
Applications Engineer
National Instruments

I Have an SCXI-110 & SCXI-1126 in multiplexed mode, how can I scan both and get accurate readings?

In Lbaview if I just scan either the SCXI-1100 or the SCXI-1126 the reading are accurate, but scanning both causes inaccurate reading on the SCXI-1126. Is this hardware not meant to be used toghter?

All of the SCXI modules can be used in the same chassis with no problems. There's not enough information here to give you any specific advice, but check you can:
1) Put your DAQ card (the one controlling the chassis) in differential mode.
2) Check your signal connections for proper referencing of you signal sources.
3) Try connecting the channel before the 'inaccurate' signal to ground and include it in the scan list. If it cleans up, then the output impedance of that source is is probably too high; slow down the channel clock rate.

I'm getting different readings for free space

So I'm a little worried. I have an early 2008 MacBook Pro with a 750GB hard drive that I recently put in. I just did a system wipe and restore, and now I'm getting 2 different readings of vastly different amounts for free space. Disk Utility and About My Mac both label it at 433.29 Gigs, but Finder rates it at 590.3 Gigs! I'm fairly certain the About My Mac has the storage space correct. I have turned off mobile Time Machine backups, and I know there's a hidden partition for Recovery, but shouldn't Finder know about this? Disk Utility shows the hard drive as fine. Any other thoughts?

See if this link offer some explanations:
http://pondini.org/OSX/DiskSpace.html
You might download from the Internet OmniDiskSweeper (free) and open it. It will give you a record of all your files and the respective sizes and you can compare that to your MBP stats.
Ciao.

Getting eronoeus readings on SCXI 1102

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