Read Encoder Position is too slow, why?

I am controlling a telescope using close-loop servo mode of 7342. What I want is to use get current position of my motor using encoder and since the position value is critical to my telescope motion system I need a fast read back of that value. However, the action is very slow, about 20ms a cycle. Is there any specification on the speed of this function? Is there any solution to speed it up? Are there any new products which is faster than this card?

The NI-735x family of motion controllers allows you to read the position much faster. The position is read from a shared register that the motion board updates. Since it is a register read, the host takes very little time to get the position information.
The NI-733x/4x families of motion controllers do send a command to the motion board that the motion board has to process and then return the data. Typically this should only take a few milliseconds or less for a read. But it is dependent on what else the motion board is doing. Things that can effect the time it takes to respond to a host request are number of axes used in arc moves, and short bursts of multiple commands sent to the board. The board has a FIFO that is 16 commands deep. If you send down multiple commands followed by a read position, each command in front of the read command has to be processed first. Which could explain why you are seeing a 20 ms read.
In NI-Motion 6.1.x we have changed the driver software to help load balance the host request with the rest of the processes running on the board. In most cases this helps performance.
What version of our driver software are you using? How fast do you really need to get the position information?
Thanks,
Rodger S.

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Time of reading encoder position

Hello,
I want to ask you people where can i learn function execution times of NI 7358 board? I'm developing driver for this card on QNX 6.5. When i send read encoder position package to 7358, the first data comes to RDB register after around 10 ms for first time. Is it normal? Is there any documentation file that includes all function execution times (average)?
Best regards.

Hi erhan,
I'm not too surprised that once the motion has started, the "Read Axis Status" function takes more time. The card should devote more resources towards managing the movement. That being said, the timing help document is only in reference to the individual function calls and as you stated the Read Axis Status alone has no latency.
Unfortunately, besides this timing help document, there isn't other documentation that is released that discusses the execution timing. If this is a bigger concern, I would try benchmarking the process on multiple computers.
Paul M
National Instruments | Applications Engineer | www.ni.com/support

Read Encoder Position Error -70012

I am using the "Read Encoder Position" and I keep getting error #-70012. There are no errors up to this point and it does not SEEM to affect the way my program runs. Does anyone know what this error is?
I did try to look up the error # to no avail.
Thanks.

Have you seen this?

Multiline string color property is too slow, why is console so much quicker?

I have a *vi that I am trying to use to format a multi-line string indicator with colors. The idea is that the data represents network traffic and must be formatted as shown in columns. I realize that there is an upper limit on the horizontal size of the string control of around 2000 characters. The standard console can be 9999 character wide. Second issue is that when I use a property node the iterations take forever to process since I am not able to concurrently apply the formatting to the string as I right them to the string window. I realize that I am using white space as filler and that this is causing a delay but in general this is taking way too long to format. Is there anyway to speed this up and go more than 2000 characters wide? If not is there a simple way to invoke the windows console in Labview and use the format parameter show in the attached *.cpp file?
I have attached the vi along with a sample Dev C++ project showing how fast the console is in comparison when apply colors to large amounts of text data.
Solved!
Go to Solution.
Attachments:
main3.cpp ‏1 KB
Trial_071030.vi ‏236 KB

Ouch! This looks like a literal translation of text code whcih is not al all optimized for dataflow. All these local variables cause extra data copies. Your code constantly needs to switch to the UI thread.
Two ideas:
Defer panel updates while doing all the coloring.
Use shift registers instead of local variables.
Why is your 3D picture set to scale with the panel? How big is your monitor?
Message Edited by altenbach on 10-30-2007 08:23 AM
LabVIEW Champion . Do more with less code and in less time .

Encoder movement response too slow

I have a USDigital QSB-D USB/serial encoder which uses a serial uart interface at 230.4 kb/s, 8 bits, no parity, 1stop bit. The USDigital driver (USDQSB.dll) allows me to open/close and read/write to registers and provides get/set functions to set specific modes. The driver provides StreamEncoderCount function which takes threshold and intervalRate parameters. The threshold specifies count changes to trigger transmission and the intervalRate is time interval between transfers. In the attached VI I am attempting to use the StreamEncoderStatus() function to wait for the encoder index pulse which indicates the encoder has passed zero counts. When the index pulse is detected I would like to use the StreamEncoderCount function to retreive encoder counts as rapidly as possible. I am setting the threshold to 0 so it will read the count even if it is not moving and intervalRate to 1 which should be sending count value at 1.9 msec intervals. The for loop count ie 100 which should take 190 msec to read at 1.9 msec. The for loop takes over 3 sec which means that the sample rate is over 30 msec instead of 1.9 msec. I am using a notification to notify another the other while loop which plots the results. Everything works as intended except for the slow response of 30 msec per sample instead of 1.9 msec.
John
Attachments:
QSBEncoder2.vi ‏72 KB

I was not able to find your dll benchmark application to do that test but I am beyond that now. I have found the correct function to read streamed serial input from the encoder which is the USDQSB.dll function: GetCountWithTimeStamp() which apparently just reads the streamed serial input and does not query the count register repeatedly. The attached QSBEncoder3.vi uses that function and performance is as expected.
I have rewritten the encoder application to use the VISA driver. The encoder is automatically recognized as a serial device by VISA and assigned the instrument ID: ASRL3::INSTR. The attached QSBEncoder4.vi attempts to access the encoder using VISA but I don't get any response from the encoder serial port. Any ideas on what I am doing incorrectly? I am able to access the encoder using the VISA interactive control but when using the LabView QSBEncoder4.vi application I don't see any input coming from the ASRL3::INSTR device.
John
Attachments:
QSBEncoder3.vi ‏71 KB
QSBEncoder4.vi ‏80 KB

Download of Mountain Lion too slow - why?

I have just bought Mountain Lion from the App Store and for some reason it is taking a very long time to download to my Macbook Pro 10.6.8. It has been more than an hour an it is still at less than approx 1/4 of the way! How long does it usually take? my internet connection is fast and working just fine.
I need to leave to work in a couple of hours max and take my computer with me and i am afraid it will not be finished by then and I'll have to interrupt the download, is this possible? can I re-start it when i get to work and have an internet connection?
Pls help!!!!

Thanks mackack,
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I've been struggling for a year trying to appreciate my imac more than my PC. and so far, I keep turning to my PC in crunch time. I do a lot of music production and I was expecting more. I have apple logic, but find adobe audition 1.5 more functional on my old PC.... go figure.

The write operation is too slow, why?

Hi,all
I have two DS, the version is 5.2_patch_6, and I have enabled the MMR. I find one of the two DS is response slow when I do write operations, as follows:
[05/Mar/2009:11:38:57 +0800] conn=38445 op=24167 msgId=707927 - MOD dn="uid=shzadmin,ou=People,o=xxxxx" authzid="dn:uid=amAdm
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Edited by: shenhongzhou on Mar 5, 2009 12:09 AM

[26/Feb/2009:18:08:35 +0800] - WARNING<10307> - Replication - conn=-1 op=-1 msgId=-1 - Configuration warning Tombstone purging internal search is unindexed in replica o=xxxxx
This is a known problem (bug 6175472) and the fix is already available in 5.2p6. Look for the script called <serverroot>/bin/slapd/admin/bin/ActivateFix6175472. Run it as:
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JarURLConnection too slow, why?

Hi,
I'm trying to get some data from a zip file on a local web server. So
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Paulo

Cecilia Borg wrote:
Paulo,
Could you describe more about the circumstances around your test? I have set
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Paulo.

AWM 11g too slow, why?

Hello,
I installed the Oracle client on a client machine (Windows). I work on AWM11g with the patch ID # 6368282.
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There is not enough information here to determine what is happening. I am not sure what you mean when you state
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OLAP Blog: http://oracleOLAP.blogspot.com/
OLAP Wiki: http://wiki.oracle.com/page/Oracle+OLAP+Option
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OWB Blog : http://blogs.oracle.com/warehousebuilder/
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Hard drive read write speeds are too slow

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Download file from portal is too slow,why?

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Socket read write on Solaris 8 too slow.

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Adobe reader too slow and "not responding," why?

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Try disabling Protected Mode [Edit | Preferences | Security (Enhanced)].
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Why my Mac Pro 2009 became too slow after updated Yosemite?

Why my Mac Pro 2009 became too slow after updated Yosemite?

When the slowness is especially bad, note the exact time: hour, minute, second.
These instructions must be carried out as an administrator. If you have only one user account, you are the administrator.
Launch the Console application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad and start typing the name.
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Select the messages entered from then until the end of the episode, or until they start to repeat, whichever comes first.
Copy the messages to the Clipboard by pressing the key combination command-C. Paste into a reply to this message by pressing command-V.
The log contains a vast amount of information, almost all of it useless for solving any particular problem. When posting a log extract, be selective. A few dozen lines are almost always more than enough.
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Why my Mac Pro hard drive noise and too slow?

Why my Mac Pro hard drive noise and too slow? Totally 8 gb speed system but now very slow . Please give some suggestions

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Read Encoder Position is too slow, why?

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