Input signal between -/+10V, but output is wrong

yes, i am using the PCI-6023, input signals is between the range of +/-10V. But the output signal of DAQ is wrong, and can not display the siganl as it should be.

Hi lvg,
You have posted similar questions (I think) more than once and I still do not have enough info to be able to help you. I believe others would say the same. If you want assistance, please provide enough information to allow us to do exactly that.
Please answer as many of these questions as possible.
When you say "the output signal is wrong" are you refering to an output voltage is wrong or
is a displayed value is wrong?
What kind of software are you using when this "output" is wrong?
If is software you have developed yourself, what environment did you develop it in (i.e. LabVIEW, C++, CVI, VB, or other)?
If is software from NI, what is it called (i.e. MAX, LabVIEW examples....)?
If it is NI software, what version is it?
Does anything
seem to work correctly?
If this is code you developed yourself, please post an example so we can take a look at it.
I can generally answer most of the questions posted to this exchange, but your recent questions have me completely baffled.
Just trying to help you get the help you want.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

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I am trying to log data from 4 voltage input signal using labview, but when i use DAQ assistant i am able to log data from one signal at a time only.

I am trying to log data from 4 voltage input signal using labview, but when i use DAQ assiatant i am able to log data from one signal at a time only.I am trying to get all 4 input data to logged in a single file againt time. I am new to Labview, I need to sample this data within a couple of days can someone help please.

Naveen
Check out the info in the Analog Input section of the document linked below. (Ignore the part about Global Channels.) In Figure 5, notice that you can select multiple channels while holding <Ctrl> or <Shift>.
Developer Zone Tutorial: NI-DAQmx Express VI Tutorial
Kyle B | Product Support Engineer | ni.com/support

Bandpass filter of cFP input signal

Hi,
I have a continuous input signal from analog compact field point. In normal, the input signal is steady, but it may oscillate sometimes. I would like to detect the oscillation frequency (0.5HZ~2HZ), that means I have to build a bandpass filter to keep the signal in 0.5 to 2 hz. Is anyone have better idea to implement this function? Thsnks for help.
Fred

Fred,
Here is a small example on Point by Point filtering. The point by point VIs allow you to perform filtering and other DSP operations one sample at a time. The example uses a butterworth filter that will give you the flattest amplitud response.
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PtbyPt_FIlter.vi ‏35 KB

How to create 2 output signal locked in phase from a one input signal

Hi all,
I have a case in which I want read in a signal analog input (voltage) from a photodiode, I want to create a 2 sinewave signal locked in with same phase as the input signal and output them as analog output to my 2 laser diode. the frequency of the input signal is low aroud 15 Hz , the 2 output signal i want to be around 120 hz and 150 hz .
I am using USB - 6003 daq card.
I have created a vi to see the input signal but I dnt know how to create 2 signal from the waveform generator locked in the phase as the input signal. I have seen a PLL vi , but dont know how to use that with my program.
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Attachments:
pulse_PLL.vi ‏27 KB

Hi AnkitG,
Here are a couple of links that might help you understand a little more how the PLL work and a way to synchronize the task to perform a PLL.
http://digital.ni.com/public.nsf/allkb/07BC8D77D4E9AE258625708B007CE74F?OpenDocument
http://digital.ni.com/public.nsf/allkb/2F675A9F2162EA24862572570059A308?OpenDocument
Also, you should be able to find a lot of examples on how to accomplish the synchronization of tasks on the community, if you consider that the only consideration is that both must start at the same moment.
I hope, these examples might show you some useful concepts:
http://digital.ni.com/public.nsf/allkb/EBD603683446EC13862575B3006A63A2
http://digital.ni.com/public.nsf/allkb/9E71F8D7D3CD1B0886257688004AE353
Regards,
Luis C.
National Instruments

Output to input mapping between actions in Guided Procdure

Hi,
i had requirement to create process i.e. user request for group access to manager this one developed in Web dynpro.
I can able create initial screen in process i.e. display available groups in portal using table in this user can select required groups and click submit then request pass to manager for approval but i'm unable pass whatever groups selected by user to manager view means i didn't no how to map parameters user request view to manager approval view and also tell me once pass parameters to input of manager view how to read the list of input (here selected groups by user).
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reagrds,
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It is better to avoid more customization from maintainability point of view, if possible . Meaning I would try to make standard map as much as possible(less customization, no custom functoids, less customized xslt etc). Since your source xml format and
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anytype with masscopy.
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Please mark it as Answer if this answers your question
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Why is it that when I saved the waveform of my acquired signal into a wav file, the output waveform of my saved file turn out to be different from my input signal?

Hi all,
I am currently doing a heart sound analyzer project. I acquired signal using NI USB 6008 continuosly. My program is able to saved the acquired signal into a wave file. But when I browse open the saved file, the output waveform did not look the same as the acquired input signal and also the sound of the heartbeat captured cannot be heard from the loud speaker though I have saved the file as a wav file. I am not sure if the method i use to save the acquired data as a wav file is correct. I have attach the print screen of the differences of the output I have notice and the program I have created. I would be glad if anyone here is able to troubleshoot my program.
Thanks.
Attachments:
heart sound analyzer.zip ‏257 KB

Hi Brett Burger,
Thanks for your reply. For your information, I have set the sampling rate as 10000 as for the sound format, I have set the bits per sample as 16 bit, the rate as 11025 and the sound quality as mono. I tried using your method by changing the sampling rate as 8K but still my program encounter the same problem.
I wish to also create a button that is able to generate a preformatted report that contains VI documentation, data the VI returns, and report properties, such as the author, company, and number of pages only when I click on the button. I have created this in my program, but I am not sure why is it not working. Can you help troubleshoot my program. Or do you have any samples to provide me. Hope to hear from you soon.
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Is it save to use digital output as a digital input signal for another channel

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I know this is a stupid question, but I do not have other signal generator by hand. So what I want to know is, can I use the digital output signal of my USB-6001 as an input signal for the same device but on other digital port? I did not try out directly because I do not want to burn the device down......
Thanks
Solved!
Go to Solution.

I do loop backs all the time, especially in my test systems as a way of making sure my signal is making it to the UUT pin. I typically throw in a 10k resistor just in case, but I have never had an issue.
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Probably by changing the data type that lvdaq.dll expects to write to is causing the crash. I can't test this since I have only 6.1 installed now. In any case, since the daq card is only 16 bits, the single precision is probably adequate for AI Buffer Read. If you do need the greater precision later on, you should be able to change representation in any one of the upper level VIs.

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How do I reduce the time from the detection of a input threshold to changing the output?

Hi,
I am using LabWindows 8.1 and a PXI-4461 with Vista (home) on a 2.81 GHz Dual Core Processor. I wrote code to do the following:
(1) output a ramp, input a signal concurrently (precise sychronization of these two is not important at this point)
(2) if the input signal rises above 0.5 V, hold the output constant for 2 seconds, while continuing the input
(3) finish the ramp
More info: I do a continuous sampling, with 4 samples per Write, to do the output. The input is read and analyzed with RegisterEveryNSamples (where N = 4). The communication between the tasks is through a global variable "trap," which is set to 1 when threshold is reached. I achieve holding the output constant by stopping the task (maintain existing value = true), and then restarting after the pause. At 40kHz and 4 samples per Write, the limit imposed by the discrete data blocks would be 0.1 msec, but in fact I am getting delays of about 2.5 msec. My write buffer is 120x4 samples, just so that there is space for me to write. I do need to save the input data after the
acquisition, preferably the whole sweep, but most importantly the data
while the output is held constant.
So my questions are:
(a) Does it really take 2 ms to stop a task? When I put in "Timer()" functions as below, I get a difference of 0.002, which is of course limited to the resolution of the Timer() function. Returning from a function (the EveryN callback) should not take that long, right?
(b) Can you suggest any better ways of doing this?
/*****begin excerpt *****/
DAQmxErrChk (DAQmxRegisterEveryNSamplesEvent(inputTaskHandle,DAQmx_Val_Acquired_Into_Buffer,4 ,0,EveryNCallback,NULL));
DAQmxErrChk (DAQmxWriteAnalogF64(outputTaskHandle,480,0,10.0,DAQmx_Val_GroupByChannel,outData,&written, NULL));
DAQmxErrChk (DAQmxStartTask(inputTaskHandle));
DAQmxErrChk (DAQmxStartTask(outputTaskHandle));
    for (count =120;count<10000; count++)
        if (trap==0) {
            DAQmxErrChk (DAQmxWriteAnalogF64(gTaskHandle,4,0,10.0,DAQmx_Val_GroupByChannel,&outData[count*sampsToWrite],&written,NULL));
        } else {
                DAQmxErrChk (DAQmxStopTask(outputTaskHandle));
                time2 = Timer();
                done = 1;
                ProcessDrawEvents();
                ProcessSystemEvents();
                Delay (2.0);
                trap = 0;
                count++;
                DAQmxErrChk (DAQmxWriteAnalogF64(outputTaskHandle,480,0,10.0,DAQmx_Val_GroupByChannel,&outData[count*4],&written,NULL));
                count = count+119;
                DAQmxErrChk (DAQmxStartTask(outputTaskHandle));
/*****end excerpt *****/
int32 CVICALLBACK EveryNCallback(TaskHandle taskHandle, int32 everyNsamplesEventType, uInt32 nSamples,void *callbackData)
    DAQmxErrChk (DAQmxReadAnalogF64(taskHandle,nSamples,10.0,DAQmx_Val_GroupByScanNumber,&readData[inCount*nSamples],nSamples,&numRead,NULL));
    if (trap == 0 && done == 0) {
        for (i=0; i<nSamples; i++) {
            if (readData[inCount*nSamples+i] > 0.5) {
                trap = 1;
                time1 = Timer();
                break;
    } else done = 1;
    inCount++;
Error:
    return 0;
I would appreciate any help or advice! Thanks. (Sorry about oddities in the code.)

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Acquiring two input signals simultaneously

Hi,
I have an LVDT and a force sensor (both attached to a motor) plugged into my SC board and I am trying to read out & save the output data from both sensors simultaneously while the motor is in motion. The SC-2350 board is connected to the laptop via DAQCard 6036E . Two questions:
1) in my block diagram, the DAQ assistant blocks for both sensors are wired to their respective waveform graphs (one for the LVDT signal and one for the force signal), the whole being included in a while loop (which remains true until the motor stops moving). When running the program, only one signal is read out at a time and I have no control on which signal is transmitted (this seems to occur in a random fashion). Do I need to "link"/synchronize the two DAQ assistants in some ways so that both signals will appear simultaneously? If so, how would it be possible?
2) ideally, I'd like to read out both input signals on the same graph (with 2 different y-scales but the same time scale) to observe the phase shift. I tried to "bundle" the two data output coming from the two DAQ assistants but it resulted in an error saying that the two outputs were of different types. Is there a way to plot these two physical quantities on the same graph even though they're different and come from different sensors?
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Hello Dani,
I assume, based on your position sensors and the image you posted, that you are using counters to acquire your data. Is this correct? If so, it is important to note that you cannot add multiple counter operations to a single task because they have different timing requirements and all channels in a single task must share the same timing and triggering. In fact, if you attempt to add a second counter channel to a DAQ Assistant for a counter operation, you will receive the following error when you try to close the configuration window:
So, you will have to use two different tasks to acquire your counter data. You can do this either by using two separate DAQ Assistants or by using two different tasks in the NI-DAQmx sub-VIs in LabVIEW. Since you are trying to compare the phase difference between the two measurements, you will also need to synchronize the operations so that you are reading from both counters simultaneously. There are several resources online which discuss synchronizing counters, and I have linked some that I thought might be useful below:
KnowledgeBase 1JPES6LL: How Do I Synchronize a Buffered Quadrature Encoder Measurement to a Signal
KnowledgeBase 3GGATSCC: Hardware Counter Start Trigger for Counter Synchronization
It would probably be easier to use the NI-DAQmx Sub-VIs to implement this synchronization because they give you more control over specific parameters of your task. You can use the NI Example Finder to browse some examples which use the NI-DAQmx sub-VIs for counters. You can open the NI Example Finder by going to Help>>Find Examples... in LabVIEW. Once in the NI Example Finder, you can find the counter examples by selecting the Browse tab and navigating to Hardware Input and Output>>DAQmx>>Counter Measurements; then you can select the Position category (shown below) to find the Position measurement examples.
Let us know if you have any other questions about taking position measurements.
Message Edited by Matt A on 04-09-2008 03:55 PM
Matt Anderson
Hardware Services Marketing Manager
National Instruments
Attachments:
Error -200147.jpg ‏32 KB
Example Finder Position.jpg ‏124 KB

Crazy problem with FSM in VHDL already synchronized the input signals

background:
To Let FPGA communicate with a DSP board. i am trying to send three datas from DSP board to the FPGA board.
code:
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity dsp_com is port
clock : in std_logic;
FPGA_CLK : out std_logic;
led1: out std_logic_vector(3 downto 0) := (others => '1');
Reset: in std_logic :='Z';
dsp_db : inout std_logic_vector(12 downto 0) := (others =>'Z');
dsp_db_output : out std_logic_vector(12 downto 0);
dsp_db_input : in std_logic_vector(12 downto 0);
wr_en : out std_logic:='0'; -- initial state is input
FPGA_ACK : out std_logic := '0'; --default state is 0
DSP_ACK : in std_logic := 'Z'
end dsp_com;
architecture FSM_Moore of dsp_com is
TYPE State_type IS (S0, S1, S8, S9, S10, S11); -- 12 States
signal PresentState: State_type;
signal s_DSP_ACK : std_logic ;
signal s_Reset : std_logic;
signal s_dsp_db_input : std_logic_vector(12 downto 0);
signal Adc_address : std_logic_vector(3 downto 0);
signal Adc_buffer : std_logic_vector(12 downto 0);
signal data_from_dsp1 : std_logic_vector(3 downto 0);
signal data_from_dsp2 : std_logic_vector(3 downto 0);
signal data_from_dsp3 : std_logic_vector(3 downto 0);
begin
--5k Hz signal work as FPGA_CLK
clkdsp : process(clock)
variable count : integer range 0 to 2000 :=0;
variable n :std_logic := '0';
begin
if rising_edge(clock) then
count := count + 1;
if(count >= 2000) then
n := not n;
FPGA_CLK <= n ;
count := 0;
end if;
end if;
end process clkdsp;
synchronous : process(clock)
begin
if rising_edge(clock)then
s_DSP_ACK <= DSP_ACK;
s_Reset <= Reset;
s_dsp_db_input <= dsp_db_input;
else
null;
end if;
end process synchronous;
--read the address and get the data
--first: process(clock,s_Reset)
-- begin
-- if (s_Reset = '0') then
-- PresentState <= S0;
--elsif rising_edge(clock) then
-- PresentState <= PresentState;
-- end if;
-- end process;
first : process(s_Reset, clock)
begin
if (s_Reset = '0') then
PresentState <= S0;
elsif(rising_edge(clock)) then
case PresentState is
when S0 => if s_DSP_ACK = '1' then PresentState <= S1;
else PresentState <= S0; end if;
-- wr_en <= '0'; -- input
-------------------------------single read ADC------------------------------------
when S1 =>
if ((s_DSP_ACK = '0') and (s_dsp_db_input(3 downto 0) = "0100")) then PresentState <= S8;
else PresentState <= S1;end if;
-- wr_en <= '0'; -- input
--------------------------receive 3 datas in sequence ------------------------------------
when S8 => if s_DSP_ACK = '1' then PresentState <= S9;
else PresentState <= S8 ; end if;
--wr_en <= '0'; -- input
when S9 => if s_DSP_ACK = '0' then PresentState <= S10;
else PresentState <= S9 ; end if;
--wr_en <= '0'; -- input
when S10 => if s_DSP_ACK = '1' then PresentState <= S11;
else PresentState <= S10; end if;
--wr_en <= '0'; -- input
when S11 => if s_DSP_ACK = '0' then PresentState <= S0;
else PresentState <= S11; end if;
-- wr_en <= '0';
end case;
end if;
end process;
-- Output depends solely on the current state
second : process(PresentState, data_from_dsp1, data_from_dsp2, data_from_dsp3, s_dsp_db_input(3 downto 0))
--variable DATA &colon; std_logic_vector(12 downto 0);
begin
case PresentState is
when S0 =>
FPGA_ACK <= '0';
led1 <= "0000";
wr_en <= '0'; -- input
-----------------get the adc-buffer--------------
when S1 =>
adc_address <= s_dsp_db_input(3 downto 0); -- get the address
FPGA_ACK <= '1';
led1 <= "0001";
wr_en <= '0'; -- input
when S8 =>
FPGA_ACK <= '0';
led1 <= "1000";
wr_en <= '0'; -- input
when S9 =>
FPGA_ACK <= '1';
data_from_dsp1(3 downto 0) <= s_dsp_db_input(3 downto 0);
if(data_from_dsp1 = "0101")then
led1 <= "1001";
else
led1 <= "0000";
end if;
wr_en <= '0'; -- input
when S10 =>
FPGA_ACK <= '0';
data_from_dsp2(3 downto 0) <= s_dsp_db_input(3 downto 0);
if(data_from_dsp2 ="0111")then
led1 <= "1010";
else
led1 <= "0000";
end if;
wr_en <= '0'; -- input
when S11 =>
FPGA_ACK <= '1';
data_from_dsp3(3 downto 0) <= s_dsp_db_input(3 downto 0);
if(data_from_dsp3 ="1000")then
led1 <= "1011";
else
led1 <= "0000";
end if;
wr_en <= '0'; -- input
end case;
end process;
end FSM_Moore ;
i have already synchronize the input signals e.g. dsp_ack, and db_input to the FSM. this is the most frequency problem that cause FSM runs misbehavior
Issue:
Issues:
when i debug the c program in DSP board and FPGA, every thing is ok ! FSM can switch to the next state according to the DSP_ACK.
but if i let the program run. i saw the state is alway stuck at S0 in FPGA, but for the DSP side, the code are still running.
anyone has any ideas to this problem?
appreciate for you guys' reply !
regard,
napon

As a bit of a guess with the limited detail you provided on your overall control mechanism I would say you are missing s_DSP_ACK = 1 when you allow the code to execute at full speed.
What is the period of your FPGA clock vs the minimum s_DSP_ACK = 1 length? I would just probe this up using CS.. Pretty simple to figure out where it is going wrong then.

Input signal between -/+10V, but output is wrong

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