Increase speed visa read write

Hi guys,
I am using the visa read and write example, but I am facing some issue when using it in a larger software, and I can only receive date when the vi has been slown down (using the lightbulb).
The programme definitely works on it own with the settings defined.
Therefore, do you have any ideas/suggestions on how to increase the speed of this vi (attached) significantly? Also, it seems to create an issue with the data read
Many thanks,
Kentmey
Kentmey
Solved!
Go to Solution.
Attachments:
Read and write.vi ‏22 KB

How are you using this code inside of another VI? If you are actually calling this VI, there needs to be some changes.
1. The port should only be initialized once at the beginning of your program and clsoed once at the end.
2. There shouldn't be any need for the bytes at port. You are set up to use a termination character. So just set the number of bytes to read to something really large (like 50 or 100) and let the VISA Read stop when it finds the termination character.
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Similar Messages

GPIB reads/writes compared with VISA reads/writes

Hello all,
Being slightly new to LV (3 months of casual use, and 1 month of really getting to know it)...
I was just wonder what the difference between VISA reads/writes and GPIB reads/writes.
Actually this is my main question: Is the GPIB Write "data" parameter and the VISA Write "write buffer" parameter the exact same thing?
Would I write the exact same command with either parameter and get essentially the same effect (if all parameters are correct?).
I have a list of GPIB commands that I want to use to write drivers for a PSA, and I really want to use VISA, and not have to change my paradigm of thinking.
I would hope they are quite similar. In fact, my research is telling me that GPIB is almost like a subset of VISA?
Thanks for your help.

The data you write with the GPIB functions is identical to the data you write with VISA. There are some things that are a bit easier to use the traditional GPIB calls but for 99+% of the time, VISA will do the trick. VISA was originally conceived as a common api for GPIB and VXI instruments. The first VXI instruments were basically the same GPIB instruments without a power supply and the user interface (buttons, screen, etc.) but they required different drivers. VISA permitted a single driver to be used for both types of instruments. Now, VISA has expanded to include serial, Ethernet, USB, and PXI and not having to change your "paradigm of thinking" is one of the big reasons that VISA is so widely used.

Error x3FFF0006 in VISA Read/Write

Hi,
I am getting this error message sometimes in VISA read and sometimes in VISA write. Its not consisten. Its only thrown in certain VIs. What could be the issue? I am attaching my main VI, where I configure serial port, and the VI where this error is thrown.
Thanks.
Attachments:
Main.vi ‏39 KB
Error.vi ‏30 KB

It's a warning and not an error.
The VI that is showing the warning is a little weird. You configure the serial port to terminate the read with a termination character but then when you do a read, specify the byte count and if the bytes read does not equal what you specify, you try to do another read. You usually don't do both.
If you specify a termination character with the VISA Configure Serial Port, the VISA Read will terminate when the termination character is detected. If you specify 100 bytes to read and there are only 50 bytes and a termination character, all you will read is 50 bytes. If you disable the termination character detection, you will always get the warning. In this case, as long as you use the VISA Bytes at Serial Port to verify that there really isn't any more data in the buffer, you can simply ignore the warning.

Visa read & write

How can I use visa (serial port) to write in COM and read from another.

Then look in the Example Finder (Help->Find Examples) and do a search for Simple Serial Write & Read. It is an ok example of how to perform a write to an instrument and then read data coming back from it. You should be able to easily expand it to write on one port and read on another.

G710 hard drive read/write speed

Hello,
I have a brand new Ideapad G710 with 1TB Serial ATA 2, 5400rpm with advertised speed of 3 Gb/s (= 384MB/s).
I am running Windows 7 ultimate x64 with SP1.
When I test hard drive read/write speed (I used CrystalDiskMark) I get results of about 100MB/s, which is 3-4 times slower than it should be.
I am not running any resource heavy applications (Resource monitor reports Disk I/O to be 0 most of the time in idle state). I have 3 partitions, each with 16-32GB paging file size and all are >90% empty. All partitions have been defragmented before testing.
Is this normal? Are there any lenovo drivers or utilities than I might be missing or that can slow/speed this?
Solved!
Go to Solution.

hi Daew,
Welcome to the Lenovo Forums.
The results that you got while running CrystalDiskMark is normal. The SATA 2 (3Gb/s) that you mentioned is actually the SATA interface support, not the actual read/write performance.
If you have a Seagate HDD (eg. ST10000LM024), check these specs
From the above specs, the unit has a cache that has a read/write max speed of 145 MB/s but there are environmental factors and power requirements to get this speed (eg. read/write speed on AC power is differente from battery power).
AFAIK, if this is the specs that is design for this drive, there's no way to speed it up.
If you're planning to upgrade in the future though, you can get an SSD for faster read/write.
Regards
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Configure VISA Read to terminate on unique character sequence

I am communicating with an instrument via a TCP connection using VISA read/write. The terminating character sequence from the instrument is "->" Is it possible to get VISA to terminate on this character sequence and basically not return these characters in a read?

No, it can only be configured to terminate on a single character. If you know that '>' will not appear in your data you can use that as your termination character. Otherwise you need to create your own read VI that will look for a sequence of characters as the termination value.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

VISA Read hangs. Get Resetting VI dialog on abort.

I also updated to the latest VISA and GPIB drivers available from National Instruments, and the same problems still occurs. Happened on the Keithley with an "*idn?" call again.
Tomek

I have the same problem with VISA Read (with a 1/2 second timeout) going to different instruments (I've seen it happen with a Keithley 2400 as the OP, but also SRS 830 Lock-in, and an SRS SIM module setup), and hanging both the VISA read and the UI.
EDIT: Added:
Windows 7 SP1 64-bit
LabVIEW version 9.0f3 (2009)
VISA Versions: 5.0
Ni-488.2 Version: 2.73
One thing that might be tripping things up is the inclusion of an IOTech Extender488/F bus extender/isolator, which uses a fiber optic cable to span a distance and provide some separation between computer ground and instrumentation.
Because of some debugging I was doing, I left NI Spy open, and have the following results from the last calls:
19859184. viParseRsrc (0x0C818D20, "GPIB0::23::INSTR", 1, 0), Process ID: 0x00001414         Thread ID: 0x00001600, Start Time: 10:48:45.027       Call Duration 00:00:00.001,Status: 0 (VI_SUCCESS)
19859185. VISA Open ("GPIB0::23::INSTR", True, 0, 0, "GPIB0::23::INSTR"), Process ID: 0x00001414         Thread ID: 0x00001600, Start Time: 10:48:45.028       Call Duration 00:00:00.038, Status: 0 (VI_SUCCESS)
19859186. VISA Lock ("GPIB0::23::INSTR", 0, 1), Process ID: 0x00001414         Thread ID: 0x00001600, Start Time: 10:48:45.066       Call Duration 00:00:00.000, Status: 0 (VI_SUCCESS)
19859187. VISA Set Attribute ("GPIB0::23::INSTR", 0x3FFF001A, 500), Process ID: 0x00001414         Thread ID: 0x00001600
Start Time: 10:48:45.066       Call Duration 00:00:00.019, Status: 0 (VI_SUCCESS)
19859188. VISA Unlock ("GPIB0::23::INSTR"), Process ID: 0x00001414         Thread ID: 0x00001600, Start Time: 10:48:45.085       Call Duration 00:00:00.010, Status: 0 (VI_SUCCESS)
19859189. VISA Lock ("GPIB0::23::INSTR", 0, 1), Process ID: 0x00001414         Thread ID: 0x00001600, Start Time: 10:48:45.095       Call Duration 00:00:00.010, Status: 0 (VI_SUCCESS)
19859190. VISA Write ("GPIB0::23::INSTR", "*idn?"), Process ID: 0x00001414         Thread ID: 0x00001600, Start Time: 10:48:45.105       Call Duration 00:00:00.018, Status: 0 (VI_SUCCESS)
19859191. VISA Read ("GPIB0::23::INSTR", 100), Process ID: 0x00001414         Thread ID: 0x00001600, Start Time: 10:48:45.123
You'll notice that it crashes on "*idn?". I'm pretty sure that in the past, it has crashed on other commands as well, and is not reproducible (for example, I ran visa read/writes to the SRS lockin every 200ms or so for the past 12 hours with no problems, with at least 60+ calls (including *idn?, which is part of a class constructor) to the Keithley.
I am happy with a solution which kills that read command, and simply issues an error -- I can handle those. But it is frustrating that I cannot trust that the VISA read will either work or throw an error that I can catch.
Any help or guidance in diagnosing this would be appreciated. Please let me know if I have missed reporting on something...
Thanks,
Tomek

Low read/write speed of ExpressCard/34

Hello!
I'm using WD My Book Studio Edition II 4Tb (http://support.wdc.com/product/kb.asp?groupid=114&lang=ru) with JMicron JMB360 ExpressCard/34 controller (http://www.jmicron.com/Product_JMB360.htm) on my MacBook Pro 17" now and seems it works slower than it should.
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Is the speed, i have now, normal?
Thank you and sorry for my... simple english.
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http://macperformanceguide.com/Reviews-SonnetSATAPro.html
I believe the info contained in this review sheds some light on the slow speeds. Clipped from the article is this:
The MacBook Pro EFI Firmware Update 1.6 kills write performance on ExpressCard SATA adapters using the Silicon Image SiI-3132 chipset, but , and it’s unclear what vendors can do about it, except that using SoftRAID seems to help (more than 2X!). Such cards include those from FirmTek, CalDigit, Sonnet (non-pro version), LaCie, etc). The Sonnet SATA Pro is not affected.
Thanks to Michael Bean of AMUG for bringing this explanation to my attention. He has tested several Silicon Image SI-3132-based cards from other vendors and found the slowdown to be uniform among them—in short it’s an Apple-induced headache for every vendor using that chipset. It’s a very good reason to consider the Sonnet Tempo SATA Pro preferentially, even given its higher cost.
I hope this helps.

VISA Read Timeout and VISA Write not working

I'm writing a program that sets a triangle wave pattern voltage (using Triangle Wave VI) to a DC power source (GWInstek PST-3202) through a RS-232 connection. I know my instrument parameters are set up correctly because I've been able to control this power source using a different VI with the same parameters. I also know I am connected to the power source because I can talk to it using MAX. I have a string indicator before my VISA Write statement that shows me the command being sent to VISA Write. It shows the correct syntax for setting a voltage on this instrument. However, when I run the VI, the voltage is not changed on my instrument, even though the correct command is sent to the instrument. After the VISA Write operation I have inserted a VISA Read function in order to read the newly set voltage from both a numeric and a waveform indicator. Using the Error Out cluster I am able to see that there is a timeout error from VISA Read. I thought perhaps I needed to clear or flush the buffer after each Read statement, but that didn't work either. I'm stumped as to why VISA Write isn't writing to the device. I have included my VI below, as well as the initialization subVI for the power supply.
Attachments:
Triangle Volt Mod.vi ‏27 KB
GW Instek initialization.vi ‏18 KB

Yep, you need to append the End of Line character to the end of your command. And for your read to work properly, you need to request the data. That requires a querry command to be sent. Look closely at the differences in command and communication structures between your working VI and your mod.
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Are my read/write speeds up to snuff? MacPro Octo 2.26

What are typical and good read/write speeds I can expect on my MacPro Octo 2.26 10GB Ram.
According to iStat, on a simple copy, I get about 65-70 MB/s read from a WD 640 caviar black internal bay, and 65-70 MB/s write to a WD 640 caviar black internal bay. Are there any apple docs that explain what we can expect, how to enhance? You can skip RAID talk, this is just basic stock computer and best operating procedures I'm speaking of. Thanks!
The OS is on a WD 74 Raptor drive.

Drives keep evolving.
It depends on what you copy, and what matters, or, where if any place is there a bottleneck?
Newer 10K VR drives maybe, boot drive is important.
SSDs definitely boost system.
Isolating I/O between drives (system, scratch, media, etc) really helps so all the work and I/O is spread out.
Newer 1TB and above drives with 500GB platters and higher density, too.
Best differs from video editing, to mild editing of files, to very heavy work in CS4.
Also, keeping your drives to 50% free space, or what I do for some drives is short-stroke so I really only use one outer partition to work with and use the rest for junk and inactive archive/backup and storage.
iStat - never used it and definitely not for benchmarking drives.

Read/write drive speed question

I've been watching the read/write speeds in Activity Monitor while I've been transfering about 250 gigs from an internal drive to an external FW 800 Weibetech Drivedock. I notice that if I plug in any other FW drive at all, even another FW800 to the back of the drivedock, the transfer speeds suddenly drop from about 43mb to about 19 or 20mb. Also happens when I plug in to the front of the Mac Pro.
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If my schematic reading-ability isn't too off, USB is the same bridge, same controller, different bus(es):
http://developer.apple.com/documentation/HardwareDrivers/Conceptual/MacPro_0608/Articles/M43_0906arch.html

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ishjen wrote:
Anybody know how fast the read/write speeds are with a USB hard drive and the Airport Extreme Base Station?
Welcome to Apple's discussion groups.
Apple's AirPort base stations aren't known for fast file serving, but for most purposed they're fast enough.
I can't comment specifically on your Aperture plan, but with some software it's important to avoid simultaneous access by more than one user.

Hard drive read write speeds are too slow

I was having an issue with 17inch macbook pro. was getting 4.0mb/s read write speed tops. and smart status failure.
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I ran this test on a fresh install of snow leopard.
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That does seem slow - on the other hand, what are you using to measure it?
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Xbench Stats: http://grab.by/7zau
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I'm looking for the read/write speeds for my Mac's.

I'm looking for read/write speeds for my Macs, but I can't find consistent data. Does anyone know the speeds or know where I can look? I have three computers:
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I think the feature is called Voice Over, and I think it's now compatible with Reader:
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Sequential read/write speeds

How can i measure sequential read/write speeds?
is there any API, library that can help me?

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Related: http://www.anandtech.com/show/7337/corsair-force-ls-240gb-review
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Increase speed visa read write

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