***Resubmitted for further review*** How can I do position maintenance using a digital input to capture an encoder count and adjust the move profile on the fly.
I have a rotary table (45:1 ratio) being driven by a stepper motor with an encoder attached to the motor. I am using a 7344 motion controller. I want to be able to do position maintenance on the move. The problem is that I am always moving in the same direction and the table has mechanical error. I have a home input on the table, which I have wired to the trigger input for the corrosponding axis. My thoughts were to capture the position when the table goes by the home input and compare it with the previous time and make the adjustment in the next move. I am just not sure what the best way to do this
is.
Hello,
So when you say that the table has mechanical error you mean that the number of steps per table revolution will vary from revolution to revolution? I apologize that I misunderstood this initially. What you could do is use high speed capture to read the position of the stepper every time the home switch (or some other mechanical switch) is hit for each revolution of travel. Then when the high speed capture lined is toggled you can read the current position and modify your next move accordingly. To get details about High Speed Capture please search for High Speed Capture from our Developers Zone at: zone.ni.com
There are examples programs on our website and examples available with the FlexMotion driver.
Please let me know if you have any further questions.
Re
gards,
Andy Bell
Application Engineer
National Instruments
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I have a rotary table (45:1 ratio) being driven by a stepper motor. I am using a 7344 motion controller. I want to be able to do position maintenance on the move. I have a home input on the table. My thoughts were to capture the position when the table goes by the home input and compare it with the previous time and make the adjustment in the next move. I am just not sure what the best way to do this is. I am thinking that I want to tie the home input to one of the trigger inputs as well as the home.
Hello,
Your best option will be to use an encoder for feedback in your system. If you use an encoder then at the end of the move, the controller will compare your trajectory position with the position the encoder reads (the actual position) and make the necessary adjustments. Also, this is all handled transparently so you won't have to worry about any complicated programming issues.
Regards,
Andy Bell
Applications Engineer
National Instruments -
How can I measure time between transitions at digital input
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Is there any good way of mesuring time period with the above setup. I don't have a module which connects to the internal multimeter in the 34970A. The other stuff I have are a HP 34903A(Actuator Module) and a HP 33120A(Function/Waveform Generator).
Any method for m
ore accurate time measurement with the above setup will be appreciated. If not, what else do I need to make accurate time measurements.Frankly I doubt that you're going to be able to measure time interval with much accuracy. You're periidically polling a static digital input and how often you poll is going to vary. You could try polling as fast as possible and eliminate as many background tasks as you can. If your tolerance for the measurement is plus or minus 100 msce, then maybe you'll get a decent measurement most of the time. If it's plus or minus 5/10 msec, then it will never happen. The pc's clock is just not that accurate and a software timed loop on Windows is not deterministic enough. Get a counter/timer board for something really accurate or use a scope to capture the waveform.
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How can an unconnected indicator read an FP digital input?
SYSTEM DESCRIPTION:
A Dell desk top computer with a Field Point system attached. There are a variety of modules including analog input, 2 digital inputs, relay out, Strain gage input, quadrature input. The system is running XP. The Labview program is written in v6.1.
PROBLEM
In an application written by others, I have found 4 front panel indicators that react to Field Point digital inputs. On the block diagram, the indicators are not wired to anything. They have no local variables and no global variables associated with them. How can they be reacting to the FP inputs? The problem is that one of the indicators reacts to the wrong input and I need to fix it. See "In(Rescue)Limit, In(Cargo)Limit, 4067 Out Limit and EStop".
Also, when the vi is launched, it starts up the FP system and the vi has no FP vi's in it and none of the sub-vi's have any FP vi's in them either. Any clues how this could be working?
I have attached the vi. There are other vi's in this project, just too many to include unless more information is needed.
Thanks,
Chris Dreike
Advantage Automation, Inc.
[email protected]
310-214-2175Chris,
It doesn't look like you attached the VIs.
You can use front panel DataSocket binding to link an indicator or control to a FieldPoint ethernet item. Right-click on the indicator and choose Data Operations>>DataSocket Connection.
Regards,
Aaron -
My computer has a white screen at start up and sits for hours. How can I fix my computer?
My computer has a white screen at start up and sits for hours. How can I fix my computer?
Take each of these steps that you haven't already tried. Stop when the problem is resolved.
Step 1
The first step in dealing with a startup failure is to secure the data. If you want to preserve the contents of the startup drive, and you don't already have at least one current backup, you must try to back up now, before you do anything else. It may or may not be possible. If you don't care about the data that has changed since the last backup, you can skip this step.
There are several ways to back up a Mac that is unable to start. You need an external hard drive to hold the backup data.
a. Start up from the Recovery partition, or from a local Time Machine backup volume (option key at startup.) When the OS X Utilities screen appears, launch Disk Utility and follow the instructions in this support article, under “Instructions for backing up to an external hard disk via Disk Utility.” The article refers to starting up from a DVD, but the procedure in Recovery mode is the same. You don't need a DVD if you're running OS X 10.7 or later.
b. If Step 1a fails because of disk errors, and no other Mac is available, then you may be able to salvage some of your files by copying them in the Finder. If you already have an external drive with OS X installed, start up from it. Otherwise, if you have Internet access, follow the instructions on this page to prepare the external drive and install OS X on it. You'll use the Recovery installer, rather than downloading it from the App Store.
c. If you have access to a working Mac, and both it and the non-working Mac have FireWire or Thunderbolt ports, start the non-working Mac in target disk mode. Use the working Mac to copy the data to another drive. This technique won't work with USB, Ethernet, Wi-Fi, or Bluetooth.
d. If the internal drive of the non-working Mac is user-replaceable, remove it and mount it in an external enclosure or drive dock. Use another Mac to copy the data.
Step 2
If the startup process stops at a blank gray screen with no Apple logo or spinning "daisy wheel," then the startup volume may be full. If you had previously seen warnings of low disk space, this is almost certainly the case. You might be able to start up in safe mode even though you can't start up normally. Otherwise, start up from an external drive, or else use the technique in Step 1b, 1c, or 1d to mount the internal drive and delete some files. According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation.
Step 3
Sometimes a startup failure can be resolved by resetting the NVRAM.
Step 4
If you use a wireless keyboard, trackpad, or mouse, replace or recharge the batteries. The battery level shown in the Bluetooth menu item may not be accurate.
Step 5
If there's a built-in optical drive, a disc may be stuck in it. Follow these instructions to eject it.
Step 6
Press and hold the power button until the power shuts off. Disconnect all wired peripherals except those needed to start up, and remove all aftermarket expansion cards. Use a different keyboard and/or mouse, if those devices are wired. If you can start up now, one of the devices you disconnected, or a combination of them, is causing the problem. Finding out which one is a process of elimination.
Step 7
If you've started from an external storage device, make sure that the internal startup volume is selected in the Startup Disk pane of System Preferences.
Start up in safe mode. Note: If FileVault is enabled, or if a firmware password is set, or if the startup volume is a Fusion Drive or a software RAID, you can’t do this. Post for further instructions.
Safe mode is much slower to start and run than normal, and some things won’t work at all, including wireless networking on certain Macs.
The login screen appears even if you usually log in automatically. You must know the login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
When you start up in safe mode, it's normal to see a dark gray progress bar on a light gray background. If the progress bar gets stuck for more than a few minutes, or if the system shuts down automatically while the progress bar is displayed, the startup volume is corrupt and the drive is probably malfunctioning. In that case, go to Step 10. If you ever have another problem with the drive, replace it immediately.
If you can start and log in in safe mode, empty the Trash, and then open the Finder Info window on the startup volume ("Macintosh HD," unless you gave it a different name.) Check that you have at least 9 GB of available space, as shown in the window. If you don't, copy as many files as necessary to another volume (not another folder on the same volume) and delete the originals. Deletion isn't complete until you empty the Trash again. Do this until the available space is more than 9 GB. Then restart as usual (i.e., not in safe mode.)
If the startup process hangs again, the problem is likely caused by a third-party system modification that you installed. Post for further instructions.
Step 8
Launch Disk Utility in Recovery mode (see Step 1.) Select the startup volume, then run Repair Disk. If any problems are found, repeat until clear. If Disk Utility reports that the volume can't be repaired, the drive has malfunctioned and should be replaced. You might choose to tolerate one such malfunction in the life of the drive. In that case, erase the volume and restore from a backup. If the same thing ever happens again, replace the drive immediately.
This is one of the rare situations in which you should also run Repair Permissions, ignoring the false warnings it may produce. Look for the line "Permissions repair complete" at the end of the output. Then restart as usual.
Step 9
If the startup device is an aftermarket SSD, it may need a firmware update and/or a forced "garbage collection." Instructions for doing this with a Crucial-branded SSD were posted here. Some of those instructions may apply to other brands of SSD, but you should check with the vendor's tech support.
Step 10
Reinstall the OS. If the Mac was upgraded from an older version of OS X, you’ll need the Apple ID and password you used to upgrade.
Step 11
Do as in Step 9, but this time erase the startup volume in Disk Utility before installing. The system should automatically restart into the Setup Assistant. Follow the prompts to transfer the data from a Time Machine or other backup.
Step 12
This step applies only to models that have a logic-board ("PRAM") battery: all Mac Pro's and some others (not current models.) Both desktop and portable Macs used to have such a battery. The logic-board battery, if there is one, is separate from the main battery of a portable. A dead logic-board battery can cause a startup failure. Typically the failure will be preceded by loss of the settings for the startup disk and system clock. See the user manual for replacement instructions. You may have to take the machine to a service provider to have the battery replaced.
Step 13
If you get this far, you're probably dealing with a hardware fault. Make a "Genius" appointment at an Apple Store, or go to another authorized service provider. -
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Welcome to the Apple Community.
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Hi,
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scottypet
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ATR Premiere Elements Troubleshooting: PE11: Accuracy of Automatic Project Preset (New Project Dialog) Setting
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Dream Spark Programs downloaded for MBA program - How can I open them?
Hi,
I downloaded Visio and some other programs below for my class through Dream Spark. However, I cannot open the programs. I have a Office 365 Home account on my Windows 8.1 computer under an Outlook email address. When I try to switch the user to my student
account I can't sign in. I have tried for several days. Here is the screen I get and I can't get any further. How can I open these programs?
wo days now. See screen shot below.Hi,
Look at the screen shot you added. Do you see the Account option on the left? You need to add your student account in that place. Once done you can start switching accounts. My guess would be that there is only one account available to choose from right
now and that is your home account.
Maurice
p.s. This forum is intended to ask questions about training and certification so your question might be somewhat misplaced here...
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I share an iTunes account with my daughter, I just got an ipad and need to set up with my own I'd for iCloud sync how can I keep my apps and music?
ColleenMcG wrote:
You can continue to share the same iTunes account ID with your daughter and set up a separate iCloud account with a different ID.
=> is this a different iCloud account for each device? I thought iCloud account ID had to match some iTunes account ID, for which we only have one i Tunes account?
You need to set up a separate iCloud account for each person that does not want to share their iCloud data. If you share an iCloud account with someone, any data you both sync with the shared account is merged, and you end up with each other's data on your device(s). If, for example, you owned two devices and someone else in the family also owned two devices, you would both want your own iCloud accounts, and you would each set up your personal iCloud account on the two devices you own. In other words, you want a separate iCloud account for each person to be used on the devices they own. Each iCloud account has to have a separate Apple ID. The ID does not need to be the same as the ID used for iTunes. Many families perfer to share the same iTunes account/ID, but maintain separate iCloud accounts with different IDs to keep there data separated.
ColleenMcG wrote:
It does not need to be the same as the ID used for iCloud.
=> what ID, iTunes? So I can have a separate iCloud account "only" ID which I also assume must be some [valid] email address? The children currently do not have email accounts anywhere.
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