Question-DAQmx: using multiple channels on a single device with a relaxation

Similar Questions

• Dedicated for each channel from multiple channels in a single task task disadvantage

  Hello

  My current acquisition software (C + c++ / GCC) encapsulates the methods rather clumsy niDAQmx C to interface with the data acquisition equipment in a class that represents a task of acquisition. This way I can create several instances, for example counter input, analog input, analog output, their terminals and the class supports all work low level as ensuring input analog fake internal is started if there are only counter entries such as the sample clock starts, or configure reminders N-sample, etc.

  It seems to work very well, and also the time seems to be good, because first of all the tasks on multiple instances of my wrapper. For triggered early, that I use

  DAQmxCfgDigEdgeStartTrig(mTask,mTriggerTerminal.toAscii().constData(),DAQmx_Val_Rising)

  in-house.

  Now my real question: what is the advantage of multiple channels, when everything seems to work fine with multiple tasks and only one channel per task? I don't see the disadvantage, it would first classify necessary acquisitions in types (I, ao,...) because several strings in a single task must be of the same type. With my approach I need not care because each channel still gets its own task.

  I don't know I'm missing something here. Maybe someone can explain it to me, maybe some limitation of multi-tasking, I have not yet read.

  Hey!

  Unless you specified for managing the it (simultaneous sampling) or modular instruments and hardware devices (see link )

  You cannot perform two tasks at the same time that access to the analog inputs, for example, because the

  ADC is a shared resource that is connected to a multiplexer, and that only one task can work in it at a time given. (see here )

  Similar restrictions often apply to other types of operations.

  I'm not aware of any performance issues, perhaps a little more memory could be used.

  So as long as your hardware supports what you are doing, you should be ok, I think,

  and it is only a question of clarity and intelligibility, ease of use and structure.

  As you use classes, I'm sure you've heard about encapsulation - so it is a

  question of how you want to design your application.

  In addition, when you work in LabVIEW, tasks feel more natural to the principle of data flow, because you have a thread for your data acquisition,

  and it works very well with our modes of standard design.

  So, if it is better for you (and works with the hardware), you can give all the channels its own task.

  Hopefully this might clarify some things,

  Kind regards

  Rome

  OR Germany

• Select multiple channels for a single task - control and shift keys do not work

  Hello

  Following the advice of several other positions, I try to choose several physical channels in the drop-down list so that I can then use the function "unflatten channel channel" later. It seems that if I hold this key is pressed or cntrl, I should be able to select multiple channels in the list, however, this does not work for me. I tried to go in the "navigation key" property for the control channel to task, but there not all listed associations. Someone else has encountered this and found a solution?  I previously around that by declaring several channels by a colon (for example, ai1:3), but it does not work for the unflatten function.

  Thank you

  Claire.

  If I understand correctly, I think that you need to do is use a task property DAQmx. Try to use the channels property to get an array of strings.

• LV 1.1, 14.5.1, 2950R USRP, DSP overflow using the example of Streaming Single-Device

  Hello.

  I use the SDR LabVIEW 1.1 and the USRP 14.5.1 with USRP-2950 device driver. Recently, I tried to use the interface of RX-host of the 'USRP RIO 40 MHz BW Single - Device Streaming PC' - example. Although the USRP device is connected to the PC via the MXIe card I get an error of overflow DSP (continuous mode). In my view must avoid an overflow of DSP for the chosen bandwidth and sample rate (examples in screenshot).

  If someone else gets this error or do I have to contact support OR? I already crushed the FPGA Image with the "NOR-SURP Configuration Utility.

  Thanks and greetings

  
  

• Continuous sampling PlotStripChart DAQmx and multiple channels

  I modified the sample code sychAI DAQmx - AO.cws slightly to provide more output wavforms. I can read at the same time on a single channel without problem. Then when I try two channels I read in an array of N (N > have a lot of examples of PlotStripChart 2, N = 2 with 2 tracks so it updates a point at a time...) I don't want that.)  samples. 0 to N - 1/2 is what AO1 (output channel 1) written on, and N/2 to N - 1, that's what written AO2. Now, if I put the number of tracks 2 and try to draw on a stripchart I get the range 0 to N - 1 on both routes.

  How to draw a picture of say 10000 samples on 2 tracks with table grouped by channel?

  Thank you

  I changed my DAQmxReadF64 to the group by number of Scan instead of channel and set skipcount = 0 and staringIndex = 0 and which has worked exactly as I wanted... but according to documentation it should not work.

• How to place outgoing files to multiple channels for a single agreement

  Hi all
  We must send the single at two different (channels) locations of the TP even HIPAA 834 document. We have unique HIPAA 834 agreement with a TP and a channel. is it possible to add both outgoing channels TP for a single TP/agreement?
  
  Thank you
  Kathar

  Hi Kathar,

  is it possible to add both outgoing channels TP for a single TP/agreement?

  A TP can have several channels, but an agreement can have only one associated channel. You can opt for the Oracle B2B here broadcast feature.

  You can read about this feature here-

  https://blogs.Oracle.com/oracleb2bgurus/entry/broadcast_feature_in_oracle_as

  Please note that this blog was written for 10g but concept and implementation is same in 11g.

  You must create two profiles TP TP even (you must use a different name/identifiers for both) and then to be part of the same group by adding identifier 'Group' in the two profiles with the same value. Middleware pass the header ' comprising:"in the name in name or an action event header.» When executing B2B will send the same message for two profiles TP.

  Kind regards
  Anuj

• Can we average channel error using multiple channels to measure the same voltage?

  I don't know how correlated error terms are between measuring channels max, but it occurred to me that, if they were relatively independent, I might be able to sample the signal even with several channels and increase accuracy.

  For example, rather than measure a voltage with an AI only at 100 kHz, I could connect up to 10 different lines to HAVE the signal, sample to 10 kHz on each line.  This should allow to reach me on average some of the error associated with each channel (, or so I think).

  Can someone speak definitively to this?

  Thank you

  Sean

  Well, if you are using a MULTIPLEXED Board (everything is not specced for simultaneous sampling) then each channel is connected to the ADC even one after the other, best that you would be able to do is extremely, extremely small variations into the paths of each channel of the multiplexer.  This would still be massively overshadowed by the inherent noise from the system and the accuracy of the device.

  Your best bets to reduce the measurement error is to oversample in one way to reduce the effects of noise and to calibrate the unit before starting each test to keep variations of temperature.  In addition, make sure you keep your calibrated Board (most of the boards have a calibration 1 year of the cycle).

  For some applications, you should also consult wiring field and considerations of noise for analog signals, How to eliminate ghosting of my measurements? and Troubleshooting unexpected tensions, floating or crosstalk on Analog Input Channels to better account for ghosting and the issues of the hour.

• How to use multiple expression in a single layer

  I need help loop expression: loopOut (type = "cycle", numKeyframes = 0);

  and remove the numbers behind coma:.value.toFixed(0);

  I tried to use ';' but only works for the first expression

  toFixed() is probably not the right tool for what you do. Try this:

  Math.Round (loopOut (type = "cycle", numKeyframes = 0))

  Dan

• Splitting of multiple lines on a single line with different fields

  Hi all
  
  I have a table. A Course_Code have section_codes several other words ('NUM' column is not sectype is just an order!)
  
  Code---num---Sec_code---Sectype---DESC---WEIGHT
  1603 1 - C 7427 - Coursework - 50
  1603--------2-------7428-----------E------------     Exam----------------     50
  
  I query this table I want to be able to see the course work, review divided on the same line. i.e.
  
  
  Code - Coursework - review
  1603 C = 50 - E = 50
  
  any help would be great

  Hello

  'Splitting' means take an element (such s as a string 'C = 50') and diviiding in smal; LER objects (such as the chains under "C" and "50"). Are you really trying to divide something, or are you trying to do exactly the opposite (for example, combine smaller chains in a larger string)?

  I think that what you are looking for is a Pivot . Like so many other things, exactly how do depends on your version of Oracle and your needs.
  Here's one way:

  SELECT       code
  ,       MIN (CASE WHEN descr = 'Coursework' THEN sectype END)
         ||  '='
         MIN (CASE WHEN descr = 'Coursework' THEN weight  END)     AS coursework
  ,       MIN (CASE WHEN descr = 'Exam'       THEN sectype END)
         ||  '='
         MIN (CASE WHEN descr = 'Exam'           THEN weight  END)     AS exam
  FROM       table_x
  GROUP BY  code
  ;
  

  It will work in Oracle 8.1 and higher. From Oracle 11.1, you can also use the SELECT... Function PIVOT.

  I hope that answers your question.
  If not, post a small example of data (CREATE TABLE and only relevant columns, INSERT statements) for all tables and also post the results desired from these data.
  Explain, using specific examples, how you get these results from these data.
  Always tell what version of Oracle you are using.

• SQL - Multiple Fetch in a single column with a comma separator

  Hello Experts,
  Good day to all...
  
  I need your help on the following scenarios. The following query returns all channels titleID. Rather than print them one under the other as a result of the query, I want the output to be in the batch of 25 values.i.e than each line must have 25 values separated by commas. IE if there are 100 titles satisfying the output, then there should be only four lines with and each line with 25 titles in comma separated way.
  

  SELECT DISTINCT title_id
             FROM pack_relation
            WHERE package_id IN (      SELECT DISTINCT fa.package_id
                                                  FROM annotation fa
                                              GROUP BY fa.package_id
                                                HAVING COUNT
                                                          (fa.package_id) <100);

  I tried with the PL/SQL block; Whereas it is printing all the values permanently :(
  I have to stop with 25 values and display.
  
  If its possible with SQL block alone. then it would be a great help
  
  

                                                         
                                                                        
  DECLARE
     v_str   VARCHAR2 (32767)  := NULL;
  
     CURSOR c1
     IS
       SELECT DISTINCT title_id
             FROM pack_relation
            WHERE package_id IN (      SELECT DISTINCT fa.package_id
                                                  FROM annotation fa
                                              GROUP BY fa.package_id
                                                HAVING COUNT
                                                          (fa.package_id) <100);
  BEGIN
     FOR i IN c1
     LOOP
        v_str := v_str || ',' || i.title_id;
     END LOOP;
     v_str := SUBSTR (v_str, 2);
     DBMS_OUTPUT.put_line (v_str);
  EXCEPTION
     WHEN OTHERS
     THEN
        DBMS_OUTPUT.put_line ('Error-->' || SQLERRM);
  END;

  Thank you...

  You can use CEIL

  Code example

  SELECT
      nt,
      LTRIM(MAX(SYS_CONNECT_BY_PATH(val,',')) KEEP (DENSE_RANK LAST ORDER BY curr),',') AS concat_val
  FROM
      (
          SELECT
              val,
              nt,
              ROW_NUMBER() OVER (PARTITION BY nt ORDER BY val)    AS curr,
              ROW_NUMBER() OVER (PARTITION BY nt ORDER BY val) -1 AS prev
          FROM
              (
                  SELECT
                      level                          AS val,
                      ceil(rownum/3)  as nt /* Grouped in batches of 3 */
                  FROM
                      dual
                      CONNECT BY level <= 10
              )
      )
  GROUP BY
      nt
      CONNECT BY prev = PRIOR curr
  AND nt              = PRIOR nt
      START WITH curr = 1;
  
          NT CONCAT_VAL
  ---------- --------------------------------------------------------------------------------
           1 1,2,3
           2 4,5,6
           3 7,8,9
           4 10
  

  Your code

  SELECT
      nt,
      LTRIM(MAX(SYS_CONNECT_BY_PATH(title_id,',')) KEEP (DENSE_RANK LAST ORDER BY curr),',') AS concat_val
  FROM
      (
          SELECT
              title_id,
              nt,
              ROW_NUMBER () OVER (PARTITion BY nt ORDER BY title_id)   AS curr,
              ROW_NUMBER() OVER (PARTITION BY nt ORDER BY title_id) -1 AS prev
          FROM
              (
                  SELECT
                      title_id,
                      ceil(rownum/25) AS nt /* Grouped in batches of 25 */
                  FROM
                      pack_relation tdpr
                  JOIN annotation fa
                  ON
                      tdpr.package_id = fa.package_id
                  GROUP BY
                      title_id,
                      fa.package_id
                  HAVING
                      COUNT (fa.package_id) < 500
              )
      )
  GROUP BY
      nt
      CONNECT BY prev = PRIOR curr
  AND nt              = PRIOR nt
      START WITH curr = 1;
  

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