Feedback for PXI 7344 motion

Hi,
I use the PXI 7344 to control a wave paddle in our wave flume.
We make regular and irregular waves.
At this moment I use a timed loop to update the position of the paddle 40 times per second (loop time 25 ms).
I use a linear interpolation between the current and the next position.
The reason for not using the contoured move is as follows:
We have also a active wave absorption system programmed into our controller. It uses 2 analog input of the PXI 7344 and calculates a correction/feedback for the wave paddle.
Therefor the movement of the paddle is not predetermined and cannot be predicted.
I would like to use the contoured move to generate a smoother motion of the paddle.
Is there a way to correct the motion during the exection of a contoured move (like the analog feedback) but then programmatically (by a calculated value ) ?
Thanks,
Tom
Tom Versluys - Dept. of Civil Engineering, Gent University
Technologiepark 904, B-9052 Zwijnaarde (GENT), BELGIUM
TEL.: +32(0)9/264.54.87, FAX: +32(0)9/264.58.37, MAIL:[email protected]

It may be that you have already chosen to map the 7344 to the local machine. That was the case for me - I have a PXI 7344 and PXI 7350, where the 7344 was already mapped to my local machine, and the option to map to local machine was grayed out. Try pressing F5 to refresh MAX and then check under the main Devices & Interfaces tab for the PXI-7344 on IP address.
Hope this helps.
-Julie

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PXI 7344 motion controller as a DAQ device for ELVIS

Hi,
Is there a way to reconfigure a PXI-7344 motion controller with its two 68-pin connectors so as to use it as a DAQ device that would receive the signals from a NI ELVIS workstation. The 7344 has a "motion I/O connector" and a "digital I/O connector". Analog outputs are even possible if I remember well, as well as digital.
Thanks

Hello,
The card does has some analog input and outputs. I would check the manual here: http://www.ni.com/pdf/manuals/370838b.pdf. The DAQmx API with a DAQ card is going to be much better than interfacing with a motion card, but you should be able to read off it at the least.
Rahul B.
Applications Engineer
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Is it possible to condition a load cell signal with a 1520 SCXI and then use it as the primary analog feedback for a 735X motion control board?

My system
PXI 1052 chassis
PXI 8196 RT controller
Flexmotion 7356 motion controller
Flexmotion 7354 motion controller
6259 M series DAQ
1520 SCXI
1520 SCXI
1314 SCXI frount mounting terminal block
DSM strain gage load cells
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My objective:
I want to measure the force on the load cells with the 1520 SCXI (i.e. excite the load cell then amplify and condition its output) then I want to use this analog (force) signal as the primary feedback for my motion control system (7356 and 7354 motion controller connected to my drives and motors).
The problem:
The motion controller boards (7356 and 7354) can be configured for force feedback control via analog feedback from a load cell. However the boards implicitly expect the load cell signal to be amplified and conditioned with and external signal conditioner rather then using an NI SCXI module. Currently I’m am reading the SCXI signals via the 6259 M seriers DAQ and consequentially have no way to route the signal into the 735X boards for force feedback control. I can use softmotion to control the motors but then I loose the fast PID update rates possible with the 735X boards.
The question:
Is it possible to condition a load cell signal with a 1520 SCXI and then use it as the primary analog feedback for a 735X motion control board?
Thanks
Patrick Aubin
Ph.D Candidate
University of Washington &
VA MedicalCenter of Excellence for
Limb Loss Prevention and Prosthetic Engineering

Hi GG,
Thank you for your feedback.
>create your own external circuitry to amplify the signal.>
True a few op-amps could amplify and filter the signal externally but the performance of such an amateur built system will never match the accuracy and functionality of the 1520 SCXI. That’s why we spent the $2500 for the professional version.
>One thing that you could do is to use a UMI with your motion controller and then wire your signal from your SCXI to the UMI.>
As I understand it the UMI is basically a break out connectivity interface for third party drives. After conditioning and amplifying the analog force signal with the SCXI module the analog signal isn’t available to wire into a UMI. To my knowledge the conditioned signal of the SCXI resides only in the PXI backplane (i.e. there is no physical access to the conditioned analog signal). Can you explain how the UMI could be help here.
Again thanks for your input GG.
Patrick

NI Motion + PXI 7344 + s-curves

I use Labview 7.0 and a PXI 7344 motion board.
I try to calculate the time and the distance needed for a motorized stage to
reach a constant speed.
The Speed, Acceleration / Deceleration and S-curves parameters are known.
Is there any way (vi or dll) to obtain the theoritical position, speed and
acceleration Vs time of a movmement ?
Or is there a way to access the data of the trajectory generator?
The "motion assistant" plot the position, speed and acceleration Vs time of
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parameters. Is it possible to have the formulas ?
Thanks for your help.
Stéphane.

Stephane,
You can use the motion assistant to visually determine the response of the parameters that are entered. At this time the exact formula is not available.
Austin Talley
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What I can do to minimise my offset in velocity in PXI 7344?

Hi,
I am using Motion control Card (PXI 7344) to control both position and linear velocity of the cylinder shaft. I am reading analog voltage from potentiometer(input range = -5V to +5V corresponding to positions 100mm and 0mm respectively). I have used DAC output (+10 v to -10V) of the motion control card as in input to Servo valve (Note: i have not used any amplifiers inbetween) which controls the hydraulic flow which inturns controls the linear movement of the cylinder shaft. In the MAX i have used Axis 1 and configured it to velocity mode selecting only the primary feedback and primary output (I haven't used secondary one) and set PID update period to 62.5 microseconds.
The problems I am facting righ
t now are
1. In the 1D interactive control of the MAX I found the current trajectory data (position and velocity) keeps on changing before starting the test (when the station if OFF) after intialising the card. I have check the Analog feedback signal from the potentiometer. It remained constant without fluctuating.
2. I can't able to achieve the set point velocity (i.e., there is always an offset and it varies with increasing setpoint). So I have used Auto-tuning option in the MAX. It automatically sets some PID parameters but it remains changing when i do it again and again.Eventhough i make changes in the PID parameters, my offset remains the same.
Whether I have to use Encoders as secondary feedback device or else what I can do to minimise my offset in velocity?

Project Support,
After reading over your description, I am still not sure that I entirely understand what is happening. Some of the questions that I have are:
-What type of motor is hooked to Axis 1?
-What type of feedback is Axis 1 using?
-Does the linear movement have feedback?
If you post back the answers to some of those questions, this forum may be a little bit better equipped to help answer your questions.
As for the questions that you posed, if you are using analog feedback, and the system issuing that feedback is turned off, then you may be seeing fluctuations from noise in the environment. This is my best guess about what is happening with problem #1. As for problem #2, I don't fully understand what you are asking. If you could post some a
dditional details about this problem, it may help to resolve the problem.
I wish you the best of luck with your application.
Regards,
Jed R.
Applications Engineer
National Instruments

Using PXI 7352 Motion card and 6025E DAQ

Dear Sir,
I am using SCXI 1520 along with PXI 1011 & E Series DAQ (6025E) to measure the Load Value of a load cell. I am also using PXI 7352 Motion card to control the velocity of a Plunger. Now my requirement is to stop the movement of the Plunger depending on the value I read from the load cell. I am not able to achieve the stoping accuracy for high speeds (around 150mm/sec) in the software. Can it be possible with the use of Motion Control card and RTSI signals? If so, how can I do that? (I am not used any limit switches as the load value at which the Plunger should stop is user programmable and I am using DAQ card in Multiplexed mode because i am reading more number of analog inputs with only one DAQ card)
Ramkumar. D
Soliton Automation,
India.

Hello.
Based on your post I am guessing that you are performing the control in software, i.e. starting a velocity move, and then reading the load cell until it reaches a threshold, then stopping the motion. As such you are essentially limited by the software control loop rates.
You are using PXI so it is possible that you are using real-time. If not, one solution could be to implement a real-time application that would be more deterministic, but again this would still depend on the software.
Depending on your system (stepper or servo), you could implement a direct analog feedback into the motion card itself, but this would require a signal which has a range much greater than your load cells. This is only a good option for servo axes. If this was somehow possible, you can tell the motion controller to move to a specified LOAD instead of a specified position/velocity. Provided you could appropriately condition the signal, this is the best choice.
Unfortunately, you cannot implement limit switches/etc over RTSI, so I believe that this will not be a good option.
A third, and probably most un-desireable option, is to output a voltage on the PXI-6025E proportional to the load received from the load cell. This voltage could then be used as the analog feedback for your motion device. This, however, still adds the software layer of delays.
I hope these ideas help you out.
Regards,
Colin C.
Applications Engineering
Colin Christofferson
Community Web Marketing
Blog

HSC limitations of the PXI-7344

I have an application where I would like to measure position data (encoder and analog value) from a relatively fast moving mechanism - so want to use the highest sampling rate possible while keeping both measurements synced. I am using the PXI-7344 for motion control and the PXI-6221/PXIe-6361 for analog DAQ.
My approach is to use one RTSI line to provide the DAQ sampling clock (possibly divided with a counter for even higher sampling rates with the DAQ card) to the HSC trigger of the PXI-7344. According to the PXI-7344 datasheet, the maximum trigger repetition rate is 1kHz, but the HSC has to be re-enabled in software after every capture. I have a program doing exactly that and it seems to be working fine - but I can't achieve rates on the HSC higher than approx. 150Hz. I assume the bottleneck here is either the host communication (most likely) or the PXI CPU is too slow with re-enabling the HSC (very unlikely - it is a 2.7GHz Quadcore and I am polling the HSC status as fast as possible in a while loop w/o any waits).
My next approach would be to write an onboard program to do the same thing and write the positions into an onboard buffer which I would read after the program is done, but according to the NI-Motion help these programs run inside the RTOS on the onboard µC with a repetition rate of 2ms, which would mean a maximum HSC rate of 500Hz (theoretical).
This is of course better than 150Hz, but now I am wondering how I could use the full capabilities of the trigger input of the card (e.g. achieve a HSC rate of 1kHz). Is this even possible/foreseen with the 7344?

HSC rearming rate is system dependent and affected by many factors. 100 Hz is a rate, that can be achieved on most systems. You might higher rates than that, but that's not guaranteed.
Onboard programming typically doesn't result in much better results, as the onboard CPU runs the user programs in a low priority task, which gets interrupted frequently by high priority tasks like limit switch monitoring and so on.
In general that's the bottleneck, that explains the limitation. On a 7344 HSC needs to get rearmed after every trigger occurrence in the user program and in both cases (host and onboard programming) the rearming needs to be executed by a low priority process on the onboard CPU.
By the way: You are referring to a 2 ms interval. In fact, that's the default value of a time slice assigned to an onboard program. This is not equal with the onboard program's cycle time, which is typically higher - depending on the amount of code and the interrupts caused by higher priority processes.
I hope that explains the behavior. For higher HSC rates up to 2 kHz please use a 7350 board.
Kind regards,
Jochen Klier
National Instruments

PXI-7344

Hello,
I am using a PXI-7344 board with a UMI-7764 accessory. So I connect it to the motion control plug and it works properly (the 4 axes are all used).
Next, I get a SCB-68 block connector because I need to get 2 more analog outputs.
So, I use a cable SH68-C68-S to connect the SCB-68 block to the PXI-7344 digital I/O plug.
But I don't know in fact how to steer the Digital Output ports from PXI-7344 to use the 2 analog outputs from SCB-68.
Moreover, I would like to know if I can steer both devices from motion port and Digital port at the same time.
Anyone an idea?
Thanks

Hello,
I would like to measure some tests on charts with a PXI-4204 board and to save them in a binary file.
I am using a VI that contains the "Analog 1DI32 Wfm NChan NSamp.vi" (from "Continuous Acq & Graph Voltage to File.vi") to acquire an analog signal.
The problem is that I had to do a "mix" with other vis:
- to be able to save the data into a binary file,
- to be able to see the waveform moving from right to left and to use the X scrollbar.
Now the problem I have concerns the reading.
When I want to use the "Graph Acquired Binary Data.vi" to read the data, there is a message of error that says the input data is not incorrect....
Anyone has an idea?
Please see the 2 files enclosed: "Continuous Binary Acquired Data.vi" and "Read Graph Data Acquired Binary File.vi" (front panel +diagram)
Thanks very much for quick reply
Attachments:
Continuous data acquired (diagram).jpg ‏162 KB

PCI-7344 motion controller encoder reset problem

I'm using a PCI-7344 motion controller for my application. I'm currently working on simple display of position and velocity using an encoder. I am able to read the encoder pulser, but I am unable to reset it. I want the encoder pulses to be display continously till I press a reset button on the screen. After pressing the reset button on the front panel, the encoder count should become zero and start counting again till I press stop button. Kindly give me a simple example of encoder reset using push button. Thanks.
Regards,
Giridhar Rajan
Cruiser Controls
Mumbai, India

This should do what you are looking for. I am not at the computer that has a motion controller card in it, so I have not tested it.
It resets the encoders for Axis 1 and Axis 2. Unless you have a different configuration for encoders and axes, it should work.
Hope that this helps,
Bob
Bob Young - Test Engineer - Lapsed Certified LabVIEW Developer
DISTek Integration, Inc. - NI Alliance Member
mailto:[email protected]
Attachments:
Reset encoders.vi ‏66 KB

PWM PID loop on 7344 motion controller

I need to control motion by PWM, with the help of 7344 motion controller.Please verify if it possible or not, and how can I do it.Please provide me(if it possible)any example of solution of this problem.

Hello,
The onboard PID circuitry can only be utilized with servos and closed loop steppers. You can write your own PID loop in software using the PWM functions and the Read Encoder Position.flx. This should work pretty well for low loop rates (since it's implemented in sw). I don't think there are any examples of it available but it should be pretty straight forward.
Regards,
Yusuf C.
Applications Engineering
National Instruments

Connect two 7344 motion controllers in one PC

Can I use two NI - PCI 7344 motion controllers in one PC. My application requires 6 axis and hence I want to use two PCI 7344 motion controllers. I am already using one. Can I configure another one in the same PC to add more axes to my current system. If yes, then how to configure the other one, so that it acts as the 5th and 6th axes in my system. I'm using LabVIEW 7.1 in my application.
Regards,
Giridhar Rajan
Automation Engineer
Cruiser Controls
Mumbai, India

You can add as many PCI-7344 boards to your PC as you want. The only
limitation is the number of PCI-slots available. In your software you
need to control the axes from the second PCI-7344 seperately from the
axes of the first one. That means that there are no built in methods to
start the axes on two or more boards synchronously. If this is not a
feature that you need then everything is quite straight forward. If you
need tight synchronization you might write an onboard program that's
running on the second board and that waits e. g. for a breakpoint
signal to be generated by the first board immediately after the axes
are started.
Assumed that you need tight motion synchronization with the additional
axes a better choice would be to use one PCI-7356 (6 axes) or a
PCI-7358 (8 axes) instead of two PCI-7344. The 735x boards are pin- and
software-compatible to the 734x boards. You could return your 7344 to
NI and buy a 735x board with a fair discount ("hardware upgrade"). If
this is an option for you please contact your local NI branch.
Best regards,
Jochen Klier
National Instruments Germany

Problems with a PCI-7344 motion controller

Hi all,
I've run into a weird problem with a NI PCI-7344 motion controller, where I
have a program that provides the motion control for my program that works
reasonably well, but when I make minor changes gets motion errors. The changes
are not specifically to the motion parts, just changing a couple of globals
that provide communication with another part of the program (and another piece
of hardware). The errors I get indicate that I am trying to enable limits
switches at the wrong time in my program. I will add that I do not get any
errors when I go through the program in debug mode
Tnx,
P.W.Monroe

The portion of my program that gets the errors uses the "Flexmotion" Find Home
and Find Index routines, which are built into the 7344 controller. In the
exampes for using these VIs, they are followed by a loop that has a VI that
monitors the status of these VIs for completion, both move complete and Home or
Index Found. The globals that I mentioned are being used to terminate the loops
if an error condition occurs elsewhere, and do not cause the program to do
anything other than terminate looking at the status and then go into a wait
loop. It crashes when it goes into the loop when I substitute a different
global, which is baffling to me, as they aren't triggering something that would
result in a race condition.

[Ask & Note] Feedback for BlackBerry 10

Hi,
I have some feedback for blackberry team but I don't know where to post it..
So I'll just post it here and please let me know if this room is not the place for my post.. Thanks..
I'm now using BB10 (Q10) and have some feedback for blackberry, so I hope this feedback can be used to improve BB10 features and also increase the easy to use and popularity of BB10
Here is the list:
1. Auto suggestion for email address (To/CC/BCC). Here I'd experienced that this features is useful and also very much annoying, why? because the list is come from the recent email address that we use to send and also from email address that have send email to us including the SPAM email (if coming to our BB Inbox), my suggestion is to make some feature/menu for user to have option for clean-up the list of email suggestion or user can delete some email in the list if they feel that email is not necessary to be there (like we will never send email to DoNotReply email from some company/domain).
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so far that's the feedbacks from me, please let me know if there is some mistake in my post..
Thanks a lot..
I hope Blackberry will grown up again and more bigger than before..
Best Regards and Thanks,
Hartawan

There is no link to suggest anything to BlackBerry but if any of the BlackBerry employees who browse these forums are going to look anywhere then it will be here...
http://supportforums.blackberry.com/t5/BlackBerry-10-Smartphone/Feature-Requests-for-BlackBerry10-OS...
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Solved!
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Hi Yann,
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Most of FCP's speed in performing functions is directly related to processor speed. The only way to increase performance would be to use a Mac with faster processors. Performance is also related to data throughput, so if you're working with high data rate video formats, a fast RAID and/or SATA (or eSATA) media storage solution would help.
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Feedback for PXI 7344 motion

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