Limit switches with MID-7604

I am trying to integrate a forward and reverse limit switch with a linear actuator. I need the actuator to find the forward limit, offset from the switch enough the disengage the switch, stop there while another task is occuring, then retract to the reverse limit, and finally offset from the reverse switch enough to disengage the switch.
I'm able to get this procedure to work one time through when the driver is just turned on, but after it's gone through the procedure more than once, the actuators no longer offset. I'm defining the offset amount in Measurement and Automation Explorer. It appears that the "find reference" VI longer finds the forward and reverse limits after the first time because if I probe the output of the "check reference" VI, the value is false even when the actuator has stopped on the limit switch.
Is there something I need to clear after each cycle? Any suggestions would be great.

Hello,
Do you have any data acquisition board? You will need one to capture the signal and process in labview.
If you don´t have one, you can search in NI website. The NI has several models.
Best regards.

Similar Messages

Mid-7604 not detecting limit switch

Hi there,
I have a stepper motor PI M-110-2S plugged in a NI MID-7604. I have been using this setup for about 3 years without any problems. Now it seem t hat one of the limit switch (signal negative) is not reading anymore. I’m not sure if the problem come from the stepper motor or the motor drive, but I need help to diagnose it. I have tried to check the signal between pin #7 and pin #8 and I get a constant 5V.
Any help would be greatly appreciated as my product line is down because of this problem.
Thank you,

AnalogKid2DigitalMan wrote:
Have you tried to activate/deactivate the switch manually to see if there is a change of state?
Could be a defective limit switch, what type is it (mechanical, optical, magnetic...)?
-AK2DM
I think that I've finally nailed it. I have been able to try another stepper that was on another production station and it's working fine. So the problem come from the stepper itself. The reverse limit switch doesn't seem to be working. I think the limit switch is a hall effect detector.
I'll keep you updated.

Limit Switches interfacing with PCI-7344

I am trying to figure out the best way to calibrate encoders with the PCI-7344 interface card. Should I setup my limit switches to stop the axis at the limit and then reset encoders there or what? Or should I have a home switch somewhere in the center of travel and let Labview reset the encoders at that point? The 7344 card has digital I/O but they are not configured as anything at the moment. I assume there is a vi to do this? What is the accepted way to do this?
Perry

Hi Perry,
What sort of behavior is your motion system going to have? Typically, you would want for one end (if linear) to be the home. So, I would probably approach it that way. But, what is your system going to be like? As for the digital I/O, there is a palette of VIs to handle this within the NI 73XX functions palette. See the pic.
Matt J.

How to find center using software limit switches

Hi,
I'm using 3 stepper motors w/ incremental encoders (by Agilent technologies), NI 7344 board and NI MID-7604 power controller.
I don't have hardware limit switches and I don't have a need for them. I found the software limit switch option under MAX and tried configuring them. I've been testing with LabView's One Axis Find Reference with Status Monitor.vi and I'm having problems.
Under max my motors are configured as closed loop/absolute position/2000 steps per cycle. I set my software limits to 2000 forward and -2000 reverse. In the vi i'm specified Find Center under search type and the motor just seems to keep turning in clockwise direction and then abruptly stops with a modal error: -70166 saying that the axis tripped on the following error.
I would greatly appreciate detailed information on what I may be wrongly configuring in MAX and how to do it properly. Thanks in advance.
-Roman

Hello Jochen,
I have a correct setting for my encoder counts and my steps per revolution. I have manually checked the rotation and the encoder outputs 1600. That is the number I have set.
I'm using the load software limits vi and I'm not having any luck with this. I'm including my vi for your review. Your help is greatly appreciated.
Roman
Attachments:
One-Axis Find Reference with Status Monitor.vi ‏120 KB

How does MID-7604 measure peak current?

What are the details about how the MID-7604 measures and regulates motor winding current?
We manufacture motion systems incorporating small step motors. One of our customers has ordered a motion system with the MID-7604. This is our first experience with the MID-7604.
When duplicating motor performance comparable to our other Step-motor Controllers, we must set the MID-7604 to 3X the motor's traditional rated peak current. For example, for a super-small MicroMo/Arsape Step motor, we traditionally limit the current to 250mA (RMS). However, with the MID-7604, we must raise the current limit to 700mA (peak) to achieve the same performance.
While we're not sure about the current regulation philosophy of our other Step-motor Controllers, the Step-motor Manufacturer's Specification Sheet limits the current to 250mA per phase with both phases energized to prevent overheating. Pumping in 700mA from the MID-7604 to achieve comparable performance just seems excessive. However, we're just playing with numbers here and not knowing what they mean. In the end, we're ignoring the numbers and instead, measuring motor torque and winding temperature in order to set the peak current switches on the MID-7604.
* How can we think of the current setting for the MID-7604?
* Is it not a PWM device that using width of voltage pulses to produce the current?
* What does "PEAK CURRENT" and "RMS CURRENT" mean?

Hey JThomas,
I'm sorry to hear that you smoked a stepper motor.There are a couple of reasons that your MID-7604 drive could appear to be operating strange.
There is a series of DIP switches on the front of the MID drive that allow you to set various things. One of those DIP switches is the current reduction switch. This switch is default in the ON position from the factory I believe so if it has never been turned off, chances are it's ON. When the Current Reduction switch is active, the stepper drive drops the current energizing the coils by 50% if there hasn't been a step in the last 500 ms. If you were gauging the strength of the drive based off of holding torque, then this could be the reason you were raising the current to a higher rating than you thought was neccesary. This settings is for customers who have an application with stepper motors that focus more on moving torque instead of holding torque.
Another possible reason for the increased current to match performance of your drives is if the bus voltage of your drives is some voltage other than 24 VDC. If your drives that you are used to using are say 36V drives, then at a lower current setting, they would provide greater torque at higher speeds because of the higher voltage being able to energize the coils faster.
Also, the KILL feature releases the axis from being actively driven. The HALT command simply locks the motor while leaving the coils energized to hold the position that it is currently in.
I hope some of this has helped you out. Let me know if I can elaborate on anything.
Thanks,
Evan D.
IMAQ/Vision R&D
National Instruments

How to include limit switches into my control loop and how to access them through Labview

I'm developing a six degrees of freedom machine with servo motors,UMI flex6 and Labview-5.1.I was unable to access the limitswithes.So I would like to know the connections diagram,UMIflex6 board settings and the Vi's to be included in the program.please help me out in solving this problem.

Hi Kolakanuru,
Thanks for using our discussion forums. How you connect your limit switches depends on what type of motion board you are using. For example, if you look at the connection diagram for a PCI-7344, you can see that Forward Limit switches connect to pins 39, 45, 51, and 57. These will then pin out directly to the UMI. For the connection diagram for your particular motion control board, you can go to www.ni.com/manuals and pull up the necessary information. In regards to reading this in LabVIEW, the first thing you will want to check out is Measurement and Automation Explorer. In the interactive windows for your board, you can check the limit switch status there- Press your limit switch on and off and make sure that it changes the LED in MAX. Once that i
s all set, then you can go into LabVIEW and use the "Read Limit Status" VI which you can find in Functions>>All Functions>>NI Measurements>>Motion>>FlexMotion>>Motion I/O palette. Good luck with your application.
Regards
Dan
National Instruments

Can't open a new tab with the + for tabs. Can open with Mid mouse button. Nightly.

When I click The + to open a new tab in Nightly, it does nothing. I can open new tabs with mid ouse button, or right click>open in new tab. Just cant open a new tab via the + button. Started 3 updates ago in nightly (3 days ago pretty much).

Are you using a 32 bit Nightly build or a 64 bit Nightly build?
The 64 bit Nightly build for Windows is only generated to test for compilation errors and doesn't undergo all the tests that other builds get, so the risk that something goes wrong can be quite high.<br />
So if you do use the 64 bit version then try the 32 bit version to see if you still have this problem.
Start Firefox in <u>[[Safe Mode|Safe Mode]]</u> to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).
*Do NOT click the Reset button on the Safe Mode start window.
*https://support.mozilla.org/kb/Safe+Mode
*https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes
Create a new profile as a test to check if your current profile is causing the problems.
See "Creating a profile":
*https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
*http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues
If the new profile works then you can transfer some files from an existing profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over the problem.
*http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

How to program limit switches as on/off switches using LabView

I am attempting to write a program in LabView (using an NI USB-6008 controller) which will turn a pump on or off based on the water level in a container. I am using a floatation device along with limit switches (something like an electronic version of a toilet float switch) which I would like to use to signal the pump to turn on or off. When the bottom limit switch is triggered, I want the pump to turn on and remain on until the top limit switch is triggered. When the top switch is triggered, I want the pump to turn off until the bottom switch is triggered. I can't just use a case structure because the pump would only stay on when the switch was actually being depressed. After searching around, I've seen some indication that you could potentially use a toggle command, a trigger command, or an event structure to do this, but I'm not sure which (if any) would actually work best or the particulars about how to configure those commands to do what I want. I am still learning LabView, so simplicity in answering would be appreciated. Thank you.

Use a state machine architecture.
Read both digital lines for the "limit" switches. Depending on the reading, switch on or off the pump (in case a limit was triggered), otherwise, keep the status of the pump.
As water level shouldnt rise/sink very fast (i hope), a polling time of about 200-500ms sounds reasonable.
Norbert
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it.

Axis getting stuck at limit switch

Hi all,
The problem I'm having is that although I can control the position of the axis fairly well, if it hits a limit switch, I can't get it to move from there. It's a stepper motor controlled by a PCI-7344. I have forward and reverse limit switches as well as a home switch. I actually have two axes doing the same thing. They are facing each other so while one stepper has a positive rotation and the other a negative, they both turn the same way, if you get what I mean. Anyway one of them is working fine and stops at the limits and comes back at the next command, but the other stops and thows up a 70119 error when I try to get it to move back from the limit. I'm pretty sure everything (ie. limit switches) is wired up correctly so assuming it is, can anyone make a suggestion as to what the problem could be???
Thanks,
Damo.
PS. OMG robot smilies!!!!

Error 70119 means:
In general this error occurrs, if you either try to move further into the active limit switch or if you try to move out of an active limit switch while the forward limit switch is connected to the input of the backward limit switch and vice versa.
If you are 100% sure that the wiring is correct, please check the version of your NI-Motion driver and the board's firmware. In NI-Motion 6.0 there was an issue with this error that was fixed in later versions. The current version of NI-Motion is 7.6.
I hope this helps,
Jochen Klier
National Instruments

How to partial stroke a valve using limit switches

Hi there. I am trying to write a small piece of code which will allow me to perform a partial stroke on a valve from the open position. To perform this test, the valve has to be in the open position, and a partial stroke button needs to be pushed once. Once the partial limit switch indicates high, the valve should return to open. This is done by energising/de-energising a solenoid. The solenoid is energised when the valve is open.
This is the first time I have used labview and I am struggling to write any code. By using the manuals, I have managed to acquire and write signals, but I am struggling with the logic for this test. I realise this will probably be pretty simple for experience users, so any examples and or advice would be good.
Thanks.

Thanks Jeff,
I have had a look and tried to implement. It works ok for the partial closure part, but I also have a seperate switch for basic open close functionality, and the partial limit switch will also go high as it moves from close to open. How would I go about adding this switch so that my logic still works?
ie. Switch 1 = Valve open (high) Valve Closed (low). Solenoid is energised to go high, de-energised to go low.
Switch 2 = partial closure switch. the valve must be open for this operation to be allowed. When this switch is pressed, the solenoid is de-energised until it hits the partial closure limit switch. the solenoid then re-energises and the valve returns to open position.
Attached is something an old collegue used to perform partial closures. I think he used timing here. I would like to use the partial limit switch to re-energise during my test rather than timing. Can you advise how to modify this code to do this?
Attachments:
Example FAT.zip ‏95 KB

Is possible to give a 5V input to the umi 7764 connector blick for the limit switch inputs

I am using a umi7764 connector block for my 7344 controller. My motion control hardware provides me a 5V output in case the limit switches are enabled. But the umi 7764 connector block connections for the limit swithces are in such a way that it doesnt get any input, instead it has to be directly connected to the limit switches.Is there any way to come around this problem so that the limit switch inputs read the 5v given out by my motion control appplcation

If your drive has individual outputs for the forward, reverse, and home switches, then you could connect these to the their respective terminals on the UMI. You will need to either disable limit functionality on one component (controller or drive) or make sure the limit behavior for the devices does not conflict with each other. It probably is best if the controller handles the limits, but this will depend on your application.
If the drive only has one output to indicate that one of the switches has been activated, then you have fewer options. In this case, you should probably just use the limit protection on the drive and poll that single output with another input on the UMI.
Regards,
Brent R.
Applications Engineer
National Instruments

Limit Switches and Contour Moves.

I am developing a 4 axis contour motion system and need to know how to handle if one of the axis activate a limit switch. Does the activated axis have to be moved off the switch so the contour move can continue or can you move it off with a co-ordinated contour move?
Configuraton
LabVIEW 2013 SP1
Softmotion 2013
cRIO Crate
NI 9514 C Series Servo Drive Interface with Encoder Feedback (all 4 axis_
Paul

The controller that I am developing is a four-axis inspection delivery tool. It is made up with a vertical pole that can be moved up and down and rotate. At end of the pole there is an "arm" that can be raised and lowered; the arm can also rotate +/-45 degrees. What I want to do is to move 2 to 3 axis simultaneously so the tool end can travel along set paths. For example if the tool end is to move horizontally, the arm has to be raised (rotated) while the overall tool is lowered. To calculate the coordinated time path of each axis, I use an inverse kinematic calculation that creates a table of positions (for each axis) with the set time interval, thus the use of multi-axis contour move.
The problem that I am worried about but have not had a chance to test, is what happens when on the axis activate a limit switch, say for example the tools vertical upper or lower travel limits. With standard single axis point-to-point movement, you can always command to travel off the limit (but not through it) but it is not clear what will happen when using contour moves (single or multiple-axis). Thus the question, how to handle, when one of the axis of a coordinated contour move motion activates a limit switch.
Cheers
Paul

Limit switchs will not turn off

We are using PXI 1031 with NI Motion Assistant and the Measurement and Automation Explorer. Our limit switchs are always reading active, and when we go into Axis Configuration to try and change thigns, something is creating an update loop that prevents us from changing any of the default confiurations. Any suggestions on either the update problem or the limit switch issues? Probing the limit switches shows good performance 0V-4.8V off/on, so it is not the hardware.
Thanks,
Aaron
Solved!
Go to Solution.

What is the motion controller that you are using?
We can try to go into Measurement and Automation Explorer, expand your particular motion device, go to Motion I/O Settings and disable all limit swithces and initialize to see if the limit switch will be turned off.
Andy Chang
National Instruments
LabVIEW Control Design and Simulation

About Limit Switch

Hi,All
I use NI PCI-7344,UMI-7764 and servo motor in my project.Now I meet a problem about limit switch----That's PCI 7344 can't detect the limit
switch's status if I set the motor's velocity a little faster(for example,1500RPM).It's very dangerous,my compents are allways hit.If I set the
motor's velocity at 500RPM or 1000RPM,this situation won't happen.
After I diable the Limit Filter in MAX,this situation still happened.My limit switch is producted by OMRON,their type is EE-SX671,they are photomicrosensor.their parameter as followensing distance(slot width):5mm.Response frequency*2:1KHZ min.(3KHZ average).After I
change the photomicrosensor to mechanical switch,the problem still occur.
I am very vexatious,Where is the problem?The Response frequency is not enough?How can I resolve the problem?Pls help me!
Thanks you in advance!
B&R
EnquanLi
Striving is without limit!

Hm, I don't think that increasing the rate of deceleration will help here as in default mode the 7344 executes a HALT when a limit switch is hit (this ignores the deceleration settings). This means that the controller tries to stop the motor as fast as possible. But there are two things you could try:
Improve the PID tuning. Maybe your system is tuned too conservatively and there is some room for optimizing the stiffness of your axis. Please have a look at this link if you need help for tuning your system.
The limits of the improvements that you can achieve with PID tuning are defined by the system stability and the motor torque which is proportional to the current provided by the drive. If your drive runs into a current limit, this will also limit the torque and the deceleration capabilities of your motor. Please check if there is a way to increase the current limit of your drive (make sure that you don't exceed your motor's specs!).
Please note: Increasing the current limits may require some adjustments of the PID parameters.
I hope this helps,
Jochen

RTSI for Additional Limit Switches?

Hi,
BACKGROUND:
I have to hook up additional limit switches which will alert me to
specific positions on an XYZ linear motor stage. I have currently
hooked up several limit switches to the digital I/O ports on a UMI-7774
board which is connected to the NI-7350 (8 Axis) controller.
My goal is to have the controller recognize when a digital I/O line has
been activated and to halt the motor from proceeding any further which
may damage expensive equipment. I unfortunately require the factory
installed limits as homing indicators, and therefore can't wire the
additional limit switches into the ports provided on the UMI-7774.
From reading the documentation online and some of the forum posts it
seems like the RTSI acts like a hardware interrupt that will signal the
controller that a condition on an external device has occured.
QUESTION:
Would a proper method, to achieve my goal, be to route a digital i/o
pin to a RTSI port which (configure in MAX) which I'm able to setup in
the labview programming environment? I take it that the high-speed
capture (RTSI) ccts are virtual.
I don't necessarily need directions how to do this. I would just like
to know if I'm heading in the right direction. I'm pretty new to the
LabVIEW environment but can usually figure how to do things on the
LabVIEW interface on my own.
Thanks for your help!
Kelly Sakaki, Ph.D., B.Eng., Centre for Brain Health / Koerner Pavilion Hospital
Faculty of Medicine, University of British Columbia, 2211 Wesbrook Mall, Vancouver, B.C., V6T 2B5
[email protected] || www.kellysakaki.ca || ca.linkedin.com/in/kellysakaki

Kelly,
You should be able to continually poll a digital line on the
motion board using Read I/O Port.flx by
putting it inside of a while loop. You
could then a case structure with Enable
Limits.flx to enable the software limits whenever Read I/O Port.flx returned a high value for the line you were
interested in. These will of course not
be as deterministic as the limits in hardware, but it would probably be the
most straightforward way to suddenly activate an additional set of limits on
your axis. This document, Axis Settings for Motion
Controllers, will provide you with additional information about software
limits.
Regards,
Luke H

Limit switches with MID-7604

Similar Messages

Maybe you are looking for