NI 9219 and 22k Ohm Thermistors

Hi all,
Is there any chance to read thermistors more than 10K ?
In particular I have to use 12 22K ohm thermistors.
Thank you in advance,
Pets

Hi Pets,
Unfortunately the maximum resistance the NI 9219 can measure is 10.5 KΩ. Other posts are related to the same issue. If you need to measure temperatures below 0°C you will still need external signal conditioning (such as a shunt resistor in parallel with the thermistor): see: thermistor data acquisition using cDAQ-9172 You can even measure the thermistor with a 9215 but using this module would require external excitation current and signal conditioning too.
Regarda
HUDSON

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Has anyone any experience with a USB-6008 and reading a thermistor value

Labview 8.0 connected to a USB-6008
I am using 'BC Components' NTC Thermistor. I used the express VI to create a Vex input and entered the A,B,& C values from the datasheet. The thermistor is the 10K version and I placed a 10K resistor in series with it. I wired it as is shown in the connection diagram, and applied 2.5 volts to it.
I get completly the wrong temperature readings out of it! I called the NI help line in the UK and the engineer confirmed that I had done everything correctly but couldn't understand why it didn't work.
Any thoughts?
Steve Lawson

I had a similar problem, had it working at one point then screwed it up.
try this:
Attachments:
Temp Pressure EXpress.vi ‏92 KB

How to match impedance between AT-MIO-16 and 50 Ohm output of preamp

I am trying to count TTL signal from a preamplifier/discriminator (ARI Corp's MTS-100) using the AM9513 chip built into the NI AT-MIO-16 A/D board.
With only power to the preamp (i.e. no input signal) I get ~150,000 or so counts per second, while with a different rate meter I get normal 5-10 counts per second. These excess counts would seem to be caused by an impedance mismatch leading to ringing in the line from the preamp to the A/D board.
The TTL output from the preamp has an impedance of 50 Ohms, minimum pulse width of 10 ns. I use a coax cable with impedance of 50 Ohms that is terminated with a 50 Ohm cap just before going to the connector block for the A/D board. Bottom line, I match the imp
edance as well as I can and still get reflection. The detector,preamp,A/D board,computer,etc are all tied to the same ground. The discriminator level has little or no effect.
Could I be connecting to the connector block of the A/D board incorrectly? Is there a threshold adjustment available for the Source (i.e. Vhigh) that might be set too low?
Is this hopeless? Or are there other things to try?
Any help would be appreciated.
Thanks,
sonnymoon

Ben on 7/25/2002 answered:
"Hi its me again.
Can you see the ringing with a scope?
What exactly are you using to get the counts from the board?
Are you sure you are re-setting the counter and have the clock configed to come from your external signal?
Ben
Hi Ben,
Thanks for your help on this. I have tried using both Labview software and NI Measurement and Automation test panels. I remember trying to figure out how to address the counter correctly using Labview "Counter Start", "Counter Read", "Counter Stop" VI's. Perhaps you could confirm for me, I am putting the signal from the preamp into "Source 1" on the A/D connector board, and I use "GPCTR1" to identify the counter.
Does the "Counter Stop" VI reset the counter? I was as
suming it does. If not, how do I do that?
But, using the NI Measurement and Automation test panels, selecting "Simple event counting" and "GPCTR1" I see lots (100,000's) of counts pile up in 1 second when I should only see 5-10.
I haven't checked with a scope (we don't have one in our lab!) but I may try to borrow one to confirm it is ringing.
My basic set up is as follows:
BNC (50 Ohm) from preamp TTL out to BNC T adapter with a 50 Ohm Terminator cap.
Signal lead from BNC plug to PIN 41 (Source1) of AT-MIO-16 I/O connector. Ground lead to PIN 24 (DIG GND) which is also grounded to be the same as that of the preamp and dectector.
Thanks again for your help,
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WLS-9219 and PCI-6251

Hi,
We have PCI-6251 card for voltage acquisition at 200 sample/sec at 14bit. Now I see NI has new product for wi-fi wireless measurement. I see WLS-9219 (4-channel, 100 S/s/ch, 24-bit, ±60 V, ±25 mA universal input) may meet my requirement. But I am now sure and want ask NI expert, Does WLS-9219 can transfer 200S/sec at 14 bit???
Thanks
Liming

Hey Liming,
The 9219 does not have a flexible resolution and the max sampling rate is 100 S/s/ch. You will not be able to achieve 200 S/s/ch with this device.
What is the voltage range of the signal you are measuring? If it is within ±10 V then you may be able to use the WLS-9215, which is 16-bit and has a sampling rate of 100 kS/s/ch.
Regards,
Chris Delvizis
National Instruments

SCXI-1520 AND 700 OHM LOAD CELL?

Will the SCXI-1520 work with a 700 ohm full bridge load cell? I'm a load cell mfg proposing a 700 ohm load cell solution to a customer. He says he doesn't think the 700 ohm cell will work with his 1520. The load cell will can take a maximum 20 VDC excitation and outputs 2 mV/V.

Hi,
Can you verify that the voltage coming out of the thermocouple is correct? You can do this by measuring across the thermocouple using a hand held multimeter. You may also want to input a known voltage into the module (a simple battery would suffice) and see if this produces the correct voltage in Measurement and Automation Explorer.
Abhinav T.
Abhinav T.
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How to Setup SignalExpress to Read Thermistors on 9219 USB

Hi,
Can anyone tell me how to setup my 9219 to
read thermistors. I have used it to read TCs (type K), but can't seem
to set it up to read thermistors. I'm using SignalExpress and keep
getting the message, "No supported devices found. Creating empty
SignalExpress block. Add channels to the block by clicking Add
Channels in the toolbar." whenever I try to Add A Step. Do I need to
set something on my 9219 so that SignalExpress can recognize the
hardware correctly (i.e. as thermistor hardware)?
Thx!

Hi- Since the 9219 doesn't support thermistor tasks, I believe you might be able to work around this by creating a 2 wire resistance measurement and applying a custom scale in your task. You'll need to multiply your resistance by your current excitation to get voltage. You'll then want to map your voltages to the temperatures specified by your thermistor. We don't have much documentation on doing this in Signal Express, however, there's a really good LabVIEW program on the NI Community, here. That example at least shows the program flow of what needs to happen. Additionally, this KB is helpful in understanding what has to be done to measure a thermistor with the 9219. Have a great day!
aNItaB
Applications Engineer
National Instruments
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How to re-paint a listbox, and to display ohms symbol w/text

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The plan is to populate a listbox with such strings and set cell BG color to indicate test pass/fail.  BG color of all cells can be "cleared" (changed to default) by setting the color of cell (-2,-2) (thanks again becktho!)...
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Any help would be appreciated!
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Also, unicode 03A9 is the code for ohms.
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Thermistor reading clamped at -17 deg C

Hi signal conditioning experts.
I am measuring several thermistor temperature channels using an SCXI-1503 connected to a PCI-6221.
The thermistors when open circuit (i.e. not connected) read approximately -17.7 deg C, but when the thermistor is connected the temperature reading is correct.
All was well, I thought, until I tried to measure a temperature below -17.7 deg C, and then the reading stayed clamped at this temperature of -17.7 deg C.
The task is set up in MAX, and the minimum range is set to well below -17 deg C so this is not it. Any ideas what may be the problem?
nrp
CLA

Hi again NRP
Thank you for your patience. I have now two options for you in regards to solving this problem.
1. The SCXI-1503 as we know can only handle a thermistor up to 100 k ohms, this is why your thermistor was saturating at -17.7 deg, as although your thermistor can produce 600 k ohms (temp of -50 deg C), saturation occurs at 100 k ohms; at -17.7 Deg C. So one solution is to change your value of thermistor to one with a low recording working temperature range but no more than 100 k ohms. I have found an external pdf doc for you to see the types of thermistors that are calibrated with low temps involved. One such resistor can record temperatures to -44 Deg C with a resistance of 99.26 k ohms. (Within 100k ohm range of SCXI module) and will allow you to record the low temperatures you require. I have included a link to this thermistor below. (Model Number 44004 - first column)
http://www.omega.com/temperature/Z/pdf/z256-257.pdf
2. Use an external excitation source that will neglect the low working range of the SCXI module and can handle the 600 k ohm thermistor value. However a problem with this is a phenomenan known as 'self-heating' which can introduce large errors into your equation. The level of the voltage output signal depends directly on the thermistor resistance and magnitude of the current excitation. Do not use a higher level of current excitation in order to produce a higher level output signal because the current causes the thermistor to heat internally, leading to temperature-measurement errors. (Self heating) I have included the manual for your viewing below. With reference to page 4-12 ; self-heating errors.
http://www.ni.com/pdf/manuals/374271a.pdf
I hope this offers a solution to your problem, please let me know how you get on. Many thanks.
Many thanks for using the NI forums and I look forward to your reply.
Kind regards
David
Applications Engineer
National Instruments UK

Digital device to use to measure 3.3V logic with 5k pull-up and 10k series resistance

I have a digital instrument with the setup that is shown below. I wish to measure the logic state of the line with a National Instruments device. Which one do you recommend?
Trials and Failures: I tried using the usb-6501 but because of the 5V and 5k ohm pull-up on the insides of this device, I was getting bad readings and was told by my peers that this was the wrong instrument to use. I also tried using the digital pins on the usb-8451 and received the incorrect measurements. I need to figure out why the usb-8451 seemed to have the input pins floating when the logic level I provided as an input was a LOW.
The figure below is a representation of my signal source:

Denn2 wrote:
Thank you for the response. Since my DUT is already assembled, it is a little late to add chips. However, a coworker suggested adding a 0 ohm jumper on top fo the 10k resistor. I will see if this works and provide an update.
I was recommending adding the chip to your test circuitry, not the DUT.
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Thermocouple measurment using NI 9219

I have a NI 9219 and an omega j type thermocouple,
When i connect the thermocouple to NI9219 terminal 4 and 6 ( positive and negative terminals) and open up Signal express I don't see the voltage change! is there something else that i need to do before i can see the measurments?

chrisger wrote:
you have to use terminals 4 and 5 for thermocouples. See page 11 on the user manual: http://www.ni.com/pdf/manuals/372407a.pdf
That is correct. In my experience (the little there is), thermocouples are almost always in adjacent terminals
Message Edited by Cory K on 01-02-2009 10:41 AM
Cory K

Motor control and graphs

Hye all
I have a major problem. im using Lv to control a motor and the motor is moving a thermistor. LV is also reading the input from this thermistor and grpahing it. My problem is when the motor is off LV grpahs away perfectly yet when i press the button to turn on the motor it stops graphing and taking data yet if i turn off the motor it starts plotting again. im controlling the motor using a D.A.Q and taking in thermistor outputs with the same D.A.Q.
Any help would be immensly appreciated
Regards Martin Garvey
Attachments:
everything together half working.vi ‏176 KB

Have you tried running with execution highlighting to see where it stalls?
(I don't understand your VI at all, it makes little sense to me. Which button turns the motor on? Why are there 3 different stop buttons? What is the meaning of the two hidden "iteration (0:initialize)" terminals that never get a value? There is data dependency between the two parallel loops (via device #) so the upper loop cannot start until the lower loop finishes Is this as intended? Do you really need to send the PSU Command string with each iteration of the lower loop? What is the difference between the two case structures except for the wait? ...?)
LabVIEW Champion . Do more with less code and in less time .

Problem with Time Capsule Mod

Since I'm an audio electronics tech with a shop, a friend with a Time Capsule asked me to perform the LaPastenague fan mod using an LED, a thermistor, and a small capacitor. (He doesn't know how to solder.) This is generally nothing like what I usually work on (gear based on technology from the 1930s through the 1980s), but it seemed straightforward enough. I did the modification as carefully as humanly possible, taking static precautions, etc...
I completed the mod and reinstalled the fan. The fan was running constantly, as intended. The LED lit up. Everything seemed to be fine.
Then, after a few minutes running on my bench, the fan simply stopped running. No light from the LED. Checking with my voltmeter, I don't think that there's any voltage at the appropriate pin of the fan power connector on the PCB. I don't really have a good way of testing the fan since I specialize in older electronics; however, with the fan plugged in and the unit on, I get no voltage reading on the + side of the LED. Bypassing the LED with a 33 Ohm resistor produces no response from the fan.
I now have that awful feeling of having worked on something for a friend, having had it stop working right in front of me, and not knowing exactly what's wrong or how to proceed.
The hard drive is still spinning, and I can contact the Time Capsule via my own computer.
Any helpful suggestions would be greatly appreciated.

I am not sure how long Apple will allow this sort of discussion on the forum.. but you can email me directly. My email is on the website under the main section.
There has to be 5v permanently across the fan but your description did not include snipping the on off wire. These are 4 wire fans.. so I presume you also cut the on off wire.. check voltage on the board pins.. 5v on the white arrow.. (tiny magnifying glass stuff.. not valve socket).. and gnd on the other end pin4.. if 5v has disappeared from there you have blown the something. Use your multimeter and see if there is 5v on the other side of L1602 and the tiny via behind that.. If you have 5v there you managed to blow the inductor.. although nothing you put in circuit should do that.. it is very sensitive to short circuits.. A momentary meter probe where you short the wrong thing.. and you will blow the 5v line. Note also the socket is not pinned through the board .. it is a surface mount socket.. horrible things.. you have to be extremely gentle otherwise you will rip the socket off the board.. check for continuity between pin 1 to the back of the L1602.
Edit as easier way of testing.. use continuity on your meter and measure ohms from pin1 on the fan socket to pin 1 on the power socket.. also marked by white arrow.. and you should have 0ohms. If it is open circuit measure from the via behind L1602 on the board.. that will show if L1602 is blown. It might well be there for protection rather than inductor.
If the socket is damaged or the L1602 is blown simply wire 5v directly to the pin 1 of the socket.. and if the socket is damaged run power to fan directly from the supply.. I have done all those things. You will find 5v directly on the other side of the board.. on the larger ceramic capacitors feeding the 1.8v power supply.
A couple of more general comments.. although the fan does a good job to reduce the temperature.. one reason apple doesn't run it permanently is lifespan of the device.. it is not a fan that is going to last long term spinning 24/7.. I decided that the better solution is remove the power supply from the TC and although the whole TC gets hot, it doesn't damage anything. The hard disk and board seem to be pretty immune to the heat.. it was only the electrolytic capacitors in the power supply that were a problem.. once you get it out of the TC and run through a socket.. you simply make the supply immune to the heat generated.. secondly running a fan 24/7 it will clog with dust and so should be filtered and cleaned properly.. rather than do that.. simply remove the power supply from inside the case and open up enough vents to allow it to cool naturally.

Steinhart hart equation

Hi,
I am using a 30 K Ohm @25 C thermistor to get and set temperature at a peltier device being controlled by the controller.
To convert the readings from the device to C reading and to convert the value to be set into thermistor values from C value, I need to write a subvi to implement the same.
I dont have any document provided by the thermistor vendor. To implement the Steinhart-Hart equation, I need to know the "A, B & C" values. I tried to find it out, but never got a clue. The Convert Thermistor Reading.vi given in the labview is confusing, as I dont know how to caliberate it for 30 K Ohm @ 25 C thermistor.
Can anyone help me out.
Thanks,
Vijay

Hi,
I will be getting a value in ohms from a thermistor which is a 30k ohm @ 25 C thermistor.
I have a table that maps a given integer temperature to a ohm value like in the attachment I have attached with this post.
But to set a temperature I can use a select case structure. But when I read the temperature, I should convert the ohm value to the temperature which is difficult.
To calculate the temperature from a given R value, I have to use Steinhart-Hart equation for which I dont know the A, B and C (co efficient) values which holds true for the 30 K Ohm thermistor I have.
The vi given in labview says, its for 5k ohm thermistor. How do I accomplish this?
Thanks,
Vijay
Attachments:
ohm-temp.png ‏155 KB

Error -200452 depends on channel order

LV 2010, NI-DAQ 9.2.2, Win Vista, cDAQ 9172 chassis, NI-9211, NI-9219.
My client has the same issue with LV 8.6.1, NI-DAQ 9.1.5, Win XP, same hardware.
I am getting an error -200452 (Property not applicable) in a case where I don't understand why.
I'm assigning the user's channels to tasks in preparation for DAQ.
Chan A: is Device 1, module 1 (NI-9211), channel 1, in TC mode
Chan B is Device 1, module 6( NI-9219), channel 1, in RTD mode.
Since these are on the same DEVICE, they are being assigned to the same TASK.
I am using the property ADC TIMING MODE to get rid of 60 Hz powerline variations in the signal (even sampling at a multiple of 60 Hz doesn't reject it as well as this property does.
The error occurs at the PROPERTY NODE function.
The thing is, if I assign chan A to the task -->BEFORE<--- channel B, then the error occurs.
If I assign chan B --> BEFORE<-- chan A, the error does NOT occur, and all seems well.
I have never imposed any restrictions on my client about having to configure things in a certain order, I don't want to start now.
Why is the order being imposed on me?
The error:
The TC code on 9211:
The RTD code on 9219:
Steve Bird
Culverson Software - Elegant software that is a pleasure to use.
Culverson.com
Blog for (mostly LabVIEW) programmers: Tips And Tricks

I think the problem stems from the fact that the 9211 does not support the ADC timing property
--- I just found that out when I added the property to the 9211 case, thinking that it was the CHANGE in property value that was triggering the complaint.
and when you are using that property you are assigning it to all of the channels in the task.
--- I'm not sure I understand that. If I use the property when the task contains A, then B, I get the error.
If I use the property when the task contains B (9219), and then add channel A (9211), I get no error.
Perhaps a clearer way to state it would be:
when you are using that property you are assigning it to all of the channels ALREADY CONFIGURED in the task.
If THAT is the rule, then that would explain it. If A(9211) is ALREADY in the task when I use the property, then it's trying to apply the property to all channels already in the task, and failing. If B(9219) is the ONLY one in the task, then the property is legal. Adding the 9211 later does NOT try to apply the property to it.
Does that sound right?
Why don't you trying using the 'ActiveChans' property node to specify what channel you need:
--- I was hoping to be done with each channel as I process it. (I am processing a list of channels that the user has specified, in no particular order, and I have to configure NI-DAQ from that list).
I suppose I can add each non 9211 channel to a list, and then use the ACTIVE CHANS along with ADC TIMING MODE to specify.
Or maybe I can use the ACTIVE CHANS list AS I APPLY IT. That would mean several calls to the TIMING MODE property, one for each non-9211 channel.
What's confusing me is the statement "You must use the same ADC timing mode for all channels on a device" from the HELP for ADC TIMING MODE.
If one of those channels is a 9211 and another is not, then that statement is obviously not true.
Steve Bird
Culverson Software - Elegant software that is a pleasure to use.
Culverson.com
Blog for (mostly LabVIEW) programmers: Tips And Tricks

Odd results from ADG608 multiplexer

Hi dear enthusiasts,
I am trying to use the following circuit (in the attachments) to switch between multiple resistors using a multiplexer. Initially I had different values of resistors attached to every channel, but since I was getting very strange and HUGE!! results, I grounded all the channels except the first channel and just connected a 120 ohm resistor. I am measuring resistor readings of magnitudes of Mega ohms and I have no idea how such huge values of resistance are showing up at all. I am not sure what I am doing wrong and I really really appreciate any help.
Solved!
Go to Solution.
Attachments:
MUX and quarter_bridge combo_test design2.ms12 ‏145 KB
MUX and quarter_bridge combo_te.pdf ‏54 KB

johnsold wrote:
You cannot measure resistance directly in an active (powered) circuit. You must measure the voltage and current at the relevant points and use Ohm's Law to calculate the resistance. SImulators are jsut like real circuits in this regard.
You also need to use voltages and currents which are compatible with the devices in the circuit. With 12 V applied to Y2 you will get ~100 mA flowing through S1 of the ADG608 when it is enabled. I did not look up the specs but suspect that that is too much current.
I only have a few minutes now and cannot draw up a circuit for you. Connect V1 to Y2 through an ammeter. This will let you measure the current through the mux. Also measure the voltage at Y1. Then the switch resistance Rs = (V1 - V(Y1))/I(V1).
Lynn
Thank you very very much Lynn. I applied the setting that you were talking about which makes a very good sense and I found out that the internal S1 resistance was roughly 15 ohms. When I put a 120 ohm resistance before S1 next time I got a total resistance of around 135 ohms which makes sense considering the individual resistances of the S1 channels and the 120 ohm resistor. The 12V for V1 was also too much and I was careless about it because I thoought I had already taken that into account and had reduced it, but obviously I had not.
Once again thank you and congratulation for being nominated the Knight of NI.
I have attached my schematic for the sake of interest.
Attachments:
MUX and quarter_bridge combo_te3.pdf ‏54 KB

NI 9219 and 22k Ohm Thermistors

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