Scaling analog inputs

This is generic , so I won’t go into the hardware unless necessary, range is simplified 0-20Ma in, 0-20 scale out.
I am having problems with scaling in Lookout, my input is 0-20Ma, input conversion is done in BCD for a unipolar FS output of 16533.
My scaling in Lookout is; raw 0-16533 / eng units 0-20
The readings are like this;
Input - output
0Ma. - 0
4Ma. – 2.52
12Ma. – 11.27
20Ma. – 20
So I tried converting to BIN unipolar FS output of 4095
My scaling in Lookout is raw 0-4095 / eng units 0-20
The readings are like this;
Input - output
0Ma. - 0
4Ma. – 1.65
12Ma. – 12
20Ma. – 20
What am I missing?

Your numbers look quite linear to me, only a few counts off what is expected. The values given scale just fine with my testing. The puzzle is fun but I think it's time for you to share more about your hardware and what driver object you are using. The only hardware I have handy that uses BCD datatypes are automation direct PLCs. Every thing scales just as it should. i.e 2084 BCD =2.52 scaled, 3306 BCD scales to 3.99, likewise 3306 Dec scales to 3.99 and 2084 Dec scales to 2.52.
When you did your test what where the scaled values at each step?
%maReadScaled
000??
2554135??
751512405??
1002016533??

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SbRio analog input scaling

I have an sbRio 9612 and I'm building an application that takes analog inputs (0 - 10 vdc) and scales them to an engineering unit like psi for example. I know how to do the scaling directly on the properties of the analog input, but I was wondering if it is possible to get to those properties in the realtime? Basically the inputs should be calibrated every 6 months, and if I want to calibrate the entire system from the sensor to the actual input then I need a way to adjust the scaling or calibration of the input in the labview realtime.
Here is the example process.
1) Put a known pressure on the pressure sensor, for this example 10 psi. The pressure sensor generates a voltage that goes into AI0 and that scales it to 10.1 psi, so I want to be able to calibrate it back to 10 psi.
Any built in methods to do this?

It is unfortunate that there is not a direct way to programatically modify the scaling factors on a RIO scan engine IOV. This information is defined in the project and deployed to the target encoded into a file called variables.xml. It is possible to decode this XML file, modify the scaling factor, replace the original file and then reboot. I have mentioned this in a LabVIEW RT idea post but never got any traction. It seems fundamental that if you offer scaling configuration in the project you should be able to programmatically modify it in a built application.

Use analog input as sample clock

Hi,
I have a PCI 6115 DAQ card. I currently perform an
analog acquisition on ai0, with an external clock on PFI7. But
sometimes, my clock signal is not high enough and the acquisition does
not occur. At some NI show, I heard a trick to solve this problem :
plug the clock on analog input (say ai1), the clock signal gets
amplified by the card internal amplifiers, and then route this
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to the sampling clock. Does someone know how to do it ?
Thanks a lot,
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I tested the attached example on a simulated device so hopefully it will work on a real one without any kinks. You didn't specify your programming environment, so I'm assuming you're using LabVIEW. If not, hopefully you can translate to the appropriate ADE based on the picture of the block diagram.
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If the constraints listed above aren't to your liking, you can try to use a second AI channel as a trigger channel. This has some advantages and disadvantages. The disadvantages are that this requires you to use a trigger with your AI task and it also requires you to acquire another channel of data. You mentioned the trigger wasn't a problem so this can probably be taken care of with simple analog start trigger. The data can easily be thrown away, but depending on your sampling rates, it might require a lot of extra bus bandwidth or processing power when scaling the data. On the positive side, it doesn't require you to use up your AO channels needlessly and you can apply gain to the input signal in order to effectively increase the resolution of the trigger circuit. You can also apply a low pass filter and different terminal configuration if desired. The gain, coupling, terminal configuration, filtering, and coupling applied to the signal is controlled by the values used in the Create Channel VI and the Channel Property node. To create an example that does this, simply start with one of the shipping examples for an Analog Start trigger, change the trigger source to one of the AI channels instead of a PFI or APFI pin, and change the clock source to the AnalogComparisonEvent as shown in the attached example.
That should do it. Good luck with your application and post back if you have additional troubles.
Attachments:
AI - External Clock Using Analog Trigger Circuit.vi ‏81 KB
AI - External Clock Using Analog Trigger Circuit.JPG ‏60 KB

Covert analog input signal (NI 9203) to meaningful units

I'm very new to LabVIEW and I wanted to do something that I thought was fairly simple. Using the NI 9203 analog input module I wanted to measure pressure using a sensor that has an output of 4-20 mA. Altough I get some signal at the end on my screen, it's not realy the pressure. How can I convert this to a meaningful signal? I also took a look at the exeple VI's in the module specific file, but I don't have a clue how to use them.
Hopefully someone can help me out.
Jurgen

Hi Jurgen,
You have two possibilities. But you must first know the relation between the current created by your sensor and the pressure mesured by your sensor. Normally you should receive this kind of things with your sensor.
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I Hope this will help you.
Regards,
Julien Roland - District Sales Manager
NI Belgium - Technical Support
Don't forget to rate a good answer

CAPTURE ANALOG INPUT DROP

I have 3 analog inputs which I continuously read and display the scaled results on 3 gauges (voltage converted to pressure 0v=0Bar 10v=300Bar) the final part of my test is to record the pressure drop of one of the analog input channels from 280Bar to 0Bar this should only take 70mS, and display this on a graph against time. Im struggling to find a way to capture this I have had a look ath the Daq examples but just dont seem to get this to work. Any help would be great.

Hi
Check the below image. Might help to acquire data. I think you have to sample higher than 70msec for reading the channels.
Let me know if you have problem.
Thanks
Viral

Analog inputs no longer working on Audigy 2 ZS Platinum Pro's external dr

I have an Audigy 2 ZS Platinum Pro. After two years of use without problems, the analog inputs on the external dri've have stopped working. I get no signal from them, not even noise. All 3 inputs are silent, Line in / Mic and Line 2 in the front, and Line 3 in the back. Otherwise the dri've appears to function normally - I get output from the headphone jack, and the volume control knob works. I have not tested digital inputs or outputs, as I currently have no digital devices to connect to them.
I had made no major changes to my computer - software or hardware - when the problems began. I recently added a new SATA hard dri've, but the Audigy dri've did work after that.
I've taken steps suggested in another thread on this forum and uninstalled all Creative software and drivers, used the latest driver package's uninstall program as well as Driver Cleaner, and finally manually deleted everything related to Creative and Audigy from the system registry (and rebooted quite a few times in between). I then installed the original drivers from the CD that came with the sound card (a setup that has worked before), but still the problem persists.
Any ideas on where to even begin looking for a solution? I find it hard to believe that it's a hardware problem, since three inputs suddenly went silent at the same time, and no other connections were affected. Yet I've done as clean a reinstall as possible, and that hasn't solved the problem.
My current computer configuration:
OS: Windows XP Pro (SP2 and all latest updates)
CPU: Athlon XP 500+
RAM: 2x 52 MB
Motherboard: Abit AN7 (integrated sound chip disabled)
Video card: Sapphire Radeon 9800 Pro
Network card: D-Link DFE-530TX
Hard dri've : Seagate ST320026A, 20 GB IDE
Hard dri've 2: Maxtor 6L080J4, 80 GB IDE
Hard dri've 3: Seagate ST330083, 300 GB SATA-II

I don't have a Platinum Pro or the dri've, but a general hardware troubleshooting step I would take would be to remove the soundcard and either move it to another slot or re-seat it. Also, I'd disconnnect and reconnect all cables to and from the card and the dri've. If I had another machine I could try the card or dri've in, I'd do that. If I could borrow another dri've or even another card, I'd test those too. (Swapping parts is often the simplest diagnostic.) Yeah, maybe it's not a hardware problem, but I'd take these steps just to rule out some possibilities.
Edit: And if you can remove or disconnect the SATA dri've and restore the system to the condition before you installed it, that's another good test.Message Edited by Katman on 2-8-2005 2:56 AM

Usb 6009 multiple analog inputs

I am currently attempting to sample two different analog inputs at different sampling rates using a USB 6009. I keep getting the 'resource reserved' error and am wondering if this is not possible using this DAQ. Questions:
1. Does creating two analog input channels on the device cause this error?
2. Is it possible to sample at different rates on channels created in the same task? (i am trying to 'slow down' the second analog input to display switch points to a customer)
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I surf therefore I am....
Attachments:
demo_nolvl.vi ‏27 KB

The DAQ boards only have 1 timing clock for the analog inputs/outputs. So you can only have 1 sample rate on a given card. I would recommend just sampling at the highest of the desired rates in a single task.
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How do I use the analog input (ADC) to drive a motion profile in MAX

We are trying to use an anolog input signal from a DAQ card to control the motion contol axis. For now, we want the motor speed to follow a sinusoidal voltage waveform, and later on, we will be using a more complex velocity profile.
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How do we 'turn on' the 'slave' mode in MAX? Please talk us through the necessary steps and settings? Thanks.
Staffan

Staffan,
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I hope this helps,
Jochen Klier
National Instruments
Message Edited by Jochen on 10-02-2007 08:37 AM
Attachments:
gearing.jpg ‏162 KB

I am getting a -50101 error when trying to get analog input from a compact rio

I am just doing the initial setup of my compactRIO system and have been able to successfully add the cRio in Max and then into a new project. I created a very simple VI with analog input that I am trying to read into an indicator, following one of teh tutorials. The module I am reading the input from is a cRio-9201. The input is voltage. I have already added the module to teh project under the FPGA, which is under the RIO in the project tree. Any ideas what I may be missing would be greatly appreciated!
Thanks

The 9201 C Series module needs to be created under the FPGA Target
(cRIO-910x) in the LabVIEW Project. You can either discover the module
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As how to create the items, that's done through right-click on the
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If you don't see the FPGA Target and C Series module options, then you
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JMota

How do I acquire multiple signals in the NI cDAQ 9172 using 2 analog input modules?

Hi everyone,
Is anyone familiar with using the NI cDAQ 9172? This is my first time using it and I am not sure what exactly I am doing wrong... Alone with a NI 9233 analog input module, it works great. I can grab my 4 signals from each channel and go. However, when I add another analog input module to the mix, it gets an error. It looks like it is reading only one and not the other. It bombs at one of the DAQ start task and read task.
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Hi Jud,
Both threads are correct. The cDAQ-9172 has a single analog input timing engine, so both of your analog input modules will need to be in a single task. The other VI you referenced shows one analog input task (with channels added from two modules) as well as an analog output task. Analog output has a separate timing engine from analog input, so both of those can run in parallel independent tasks.
The beginning of this thread is a good example; a single DAQmx Create Task followed by a DAQmx Create Virtual Channel for channels from each module. Also, Getting Started with NI-DAQmx will give you the fundamentals for data acquisition, though I don't know how many of their examples use CompactDAQ.
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Synchronizing two counter frequency inputs with multiple analog inputs

Hello all,
I'm fairly new to LabVIEW and I'm trying to collect data from multiple sources with synchronized timing on the acquisition but I'm having trouble figuring it out. My problem is that I've got two counter frequency inputs, one optical tachometer reading one pulse per revolution, and a max machinery flow meter with a k factor of 12000. I can't seem to figure out how to sync the timing with my multiple analog inputs. I've been attempting to get the tachometer to sync with the analog inputs first by following the example linked here. (https://decibel.ni.com/content/docs/DOC-10785) So far each time I run it I either get a timeout error on the DAQmx read or a "Multiple sample clock pulses were detected" error (see attached image). It seems if I slow the sampling rate way down to say 10 hz and ensure that the tachometer signal is over 800-1000 RPM (13-17 Hz) before starting the VI then the program will run without errors until the RPM drops below that threshold then the "Multiple sample clock pulses" error occurs. The code is attached below.
Does anyone know of a more effective way of syncing counter frequency inputs with analog inputs? I'd like to have a VI that can show 0 RPM (and eventually 0 flow as well, but I think I need to figure out the timing of one counter before I add another as it seems I can't have two counters in the same task). Any help on this would be greatly appreciated.
LabVIEW version 13.0
cDAQ-9178 Chassis with NI 9401 for the two counter inputs and NI 9205 for the analog inputs.
Thanks!
Richard
Solved!
Go to Solution.
Attachments:
SimpleDAQ.vi ‏44 KB
LV_Error.JPG ‏31 KB

Maybe third times the charm?
So I've finally got a good handle on why the VI is having problems at low RPM though I'm somewhat embarassed how long it took me to do that
Because I have the counter time synced to my Analog input task if it doesn't see at least two pulses between the two clock pulses set by the analog input task I get the -201314 "Multiple sample clock pulses" error. This seems fine at first as it just sets a minimum RPM that I can measure and it's well below the area I'm interested in so no problems there. I tried a simple error handler that would clear the error when it happend assuming the loop would keep iterating until the RPM went above that minimum at which point I would get a signal again. This is not the case, the read function just continues to spit out the -201314 error even after the RPM is back in the readable range. So then I tried adding two case structures so that when the error occured it would stop the task, clear the error, and then start the task again on the next loop iteration (Code Attached). This also doesn't work as the error shows up again on the stop task and then AGAIN on the start task on the next loop iteration. It seems this error is not actually being cleared and once it happens it stays with the task regardless of what the error cluster is carrying.
Anyone have any ideas? The only solution I can think of is to just clear all tasks and recreate them each loop iteration until the RPM is readable again but that strikes me as a horribly clunky solution.
Richard
Attachments:
SimpleDAQ_1_Start Stop.vi ‏48 KB

Audigy 4 Pro Hub Analog inputs problem

&Analog inputs in Audigy 4 Pro external hub seem to be unsupported in Windows 7. Am I wrong?
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Issue solved... line in /Mic is now working. Audigy 4 pro analog input is supported using latest windows 7 drivers.

Scanning of analog inputs in PXI 7831R FPGA

Hi all,
I am new to Labview FPGA Module. I am using Labview 7.1.1 and Labview FPGA Module 1.1 . I am using PXI 7831R FPGA Card.
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If I scan one analog Input with 10ms scan rate for 1000ms scan duration I am getting correct values. But if I use 2 or more analong signals to scan at the same time then I am getting Multiple of periods. And also If I increase or decrease scan rate I am getting strange values. Could any body please check my code and help me.
Thanks in Advance.
Regards,
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Attachments:
AnlogIn_FPGA.zip ‏247 KB

customise your front panel with advanced picture creation metods
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How to get signal from analog input and send it to analog output (real-time)

Hi everyone,
I am doing simple task in Visual C++ and I am using PCI-6221(37 pin).
Basically, I want to send same signal from 'analog input' to 'analog output'
at the same time (almost), to make it real-time application.
Can someone please provide me sample program.
I would appreciate if you could provide me with the good tutorial which explains
step by step everything about programing NI-DAQmx for C/C++.
Best Regards,
Khassan
Solved!
Go to Solution.

This is my code in C++, you can optimize it if it looks too messy. This code reads signal from analog input and outputs it through analog output.
To make this code work additional include directories and library directories must be added from NI.
I hope it helps someone.
#include <stdio.h>
#include <conio.h>
#include "NIDAQmx.h"
#include <math.h>
#define DAQmxErrChk(functionCall) { if( DAQmxFailed(error=(functionCall)) ) { goto Error; } }
int main(int argc, char *argv[])
int32 error=0;
TaskHandle taskHandleRead=0,taskHandleWrite=0;
int32 read=0;
float64 dataRead[1000];
char errBuffRead[2048]={'\0'};
char errBuffWrite[2048]={'\0'};
bool32 done=0;
int32 written;
DAQmxErrChk (DAQmxCreateTask("",&taskHandleRead));
DAQmxErrChk (DAQmxCreateAIVoltageChan(taskHandleRead,"Dev1/ai0","",DAQmx_Val_Cfg_Default,-10.0,10.0,DAQmx_Val_Volts,NULL));
DAQmxErrChk (DAQmxCfgSampClkTiming(taskHandleRead,"",100.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,0));
DAQmxErrChk (DAQmxCreateTask("",&taskHandleWrite));
DAQmxErrChk (DAQmxCreateAOVoltageChan(taskHandleWrite,"Dev1/ao0","",-10.0,10.0,DAQmx_Val_Volts,NULL));
DAQmxErrChk (DAQmxCfgSampClkTiming(taskHandleWrite,"ai/SampleClock",100.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000));
DAQmxErrChk (DAQmxStartTask(taskHandleRead));
DAQmxErrChk (DAQmxStartTask(taskHandleWrite));
while( !done && !_kbhit() )
DAQmxErrChk (DAQmxReadAnalogF64(taskHandleRead,1,10,DAQmx_Val_GroupByScanNumber,dataRead,1000,&read,NULL));
DAQmxErrChk (DAQmxWriteAnalogF64(taskHandleWrite,read,0,10.0,DAQmx_Val_GroupByChannel,dataRead,&written,NULL));
_getch();
Error:
if( DAQmxFailed(error) )
DAQmxGetExtendedErrorInfo(errBuffRead,2048);
DAQmxGetExtendedErrorInfo(errBuffWrite,2048);
if( taskHandleRead!=0 )
DAQmxStopTask(taskHandleRead);
DAQmxClearTask(taskHandleRead);
if( taskHandleWrite!=0 )
DAQmxStopTask(taskHandleWrite);
DAQmxClearTask(taskHandleWrite);
if( DAQmxFailed(error) ){
printf("DAQmx Error: %s\n",errBuffRead);
printf("DAQmx Error: %s\n",errBuffWrite);
printf("End of program, press Enter key to quit\n");
getchar();
return 0;

Analog Input and Output in One Single VI

I need help in setting both analog input and output in one single VI. How do I assign channels to be either input or output? How do I simultaneously uses both in one single VI with a while loop structure?? Which AO am I suppose to use to obtain signal from the function generator I have built to feed into the DAQCard-1200?? Help!!
Attachments:
Test1.vi ‏48 KB

One thing you'll need to be aware of is that you will need to DMA lines: one for AI and one for AO. If you don't, then you can configure the DAQCard to do without DMA using the Config VI. But you certainly can do this.
As far as your function generator, you will want to do a buffered analog output. You will write your buffer of points to the buffer, and then tell NI-DAQ how fast to update your analog output channel with these values.
So, you can be reading from AI and checking the AO process in the same while loop. Just make sure you handle the while loop execution (the wait it exits) correctly. This can get tricky when you're doing two types of measurements.
J.R. Allen

Scaling analog inputs

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