Problems with asynchronous visa read with USB to serial port adapter

I have an application that sends and recieves data from a power supply and on most computers (desktop PCs), the application runs fine. I found that on at least one computer, using a Keyspan Tripp Lite USB to RS232 adapter, in one out of 25 queries, I wasn't getting the whole reply back from the instrument. After some debugging I found out if I switch the VISA write and read calls from synchronous to asynchronous I don't see the error any more. Is there a way to disable asynchronous mode for that computer? I'd rather not have to find all the VISA write calls in my application and update each one just to support that computer.
CLD (2014)

Try playing with the Tx ACK Advance setting on that port first. (From the Keystone config utility) You might also look into the Rx FIFO buffer settings (16 is a short default buffer)
There is no (Easy) way to universally disable Async . VISA Async tranfers MAY complete synchronously anyhow (It throws a warning when that happens) So if Keystone settings do not help you might want to swap out to a FTDI chip enabled USB - serial device.
Jeff

Similar Messages

Usb to Serial port adapter

I have a gilsson usb to serial port bi directional adapter cable which uses the Prolific pl-2303 chipset. I am attempting to use this cable to interface a Mac Mini with a Harsper PDP plasma television.
I am attempting to control the functions of the television via the serial port on the television. i.e. Turn on, input, volume, etc.
What I need is software, or source code that would allow me to send hexidecimal commands to the television and receive the task completed codes.

ZTerm will allow serial communications. Get it to ensure that throughput is happening as expected.
RealBasic will allow you to roll your own with a fair amount of ease.
A long time ago I used the above to communicate with my cellphone to send and receive text messages via the serial port, so I know it can work. Understanding the protocols is the difficult part...

USB to Serial port adapter - Mac thinks it's a modem

I’m trying to connect my Mac’s USB port to a Sony Beta SP recorder's Serial Port using a generic USB to Serial adapter which uses the Prolific PL-2303 chip.
I’m using the latest Prolific Universal driver, but when I plug in the USB cable I get a message that a ‘new network device has been detected’ and suggesting that I use System Preferences to set it up. But in System Preferences it seems to think the USB to Serial adapter is a modem and is looking for a phone number and other configuration data.
Does anyone know how to get it to work as just a serial communication device to my Sony’s serial port? If I get it working I'll be connecting it to an RS232 to RS422 adapter to talk to the Sony port.
Thanks.

Thanks Andy.
I'll have a go again. It was late last night when I was trying to set it up, so maybe a fresh brain will have more success. I did try to 'Cancel' the network preference window that opened, but got the impression that it would not work unless I did 'something'. Someone else told me I could cancel that message permanently within System Preferences, so I'll try that too. Yet another bit of advice I got was that I would have to install 'MacPorts' and run something called 'Minicom' to set up the serial parameters. Windows was so simple by comparison
As a non-techie (at least in all these software and protocol issues) I'm more than a little confused.
Regards
Message was edited by: esmonde

Audio CD not recognized with Mini but reads with Macbook?

Error message saying Audio CD not recognized with Mini but reads with Macbook pro. Both machines are using the same Samsung external usb dvd/cd player.
I've tried rebooting the mini, cleaning the disk, unplugging the drive and the Mini still won't recognize the CD's (it's a 3 cd set and all 3 disks aren't working on the Mini.
When I use the same disks and drive with my Macbook Pro everything works fine.
Any suggestions?

Hi Jay,
Certainly a strange one!?
Are these commercial or self made Discs?
Have you tried CD/DVD sharing on the MBP & see if the Mini can read them in the MBP?

Info about read or write a serial port with forms 6.0.5

Anybody can give some info. on read or write a serial port using form (Developer 6.0.5).
Thanks
MM
null

One option you can try is to develop a DLL
function to read/write serial port,
and then write a ORA_FFI procedure to call the DLL function.
Peter Ng
Calgary, Canada
null

Usb to serial port converter in lenova g560

hi this is madhan. i m using lenova g560 ideapad. there is no serial port in my laptop. For my project i need a serial port. i heard tat in market USB to serial port converters are available. Does Lenova g560 support this change?? If so is there any driver to make support to serial port?????????

If you buy a Serial-USB interface/cable you won't have any problem. Usually this accesory comes with drivers. If you have Windows 7, mayte it will detect all automaticaly.
Regards.
IPnaSh
First Spanish Community Guru - Colaborador ad honorem

Why does a standalone program created in Labview 8.5 try connecting to the internet when the program only reads data through the serial port? Firewalls object to progams that contact the internet without permission.

why does a standalone program created in Labview 8.5 try connecting to the internet when the program only reads data through the serial port? Firewalls object to progams that contact the internet without permission.
The created program is not performing a command I have written when it tries to connect to the internet, it must be Labview that is doing it. How do I stop this from happening?
Any help would be very appreciated.

It looks that way..
"When LabVIEW starts it contacts the service
locator to removes all services for itself. This request is triggering
the firewall.This is done in case there were services that were not
unregistered the last time LabVIEW executed- for example from VIs that
didn't clean up after themselves"
This is not yet fixed in LV2009.
Message Edited by Ray.R on 11-04-2009 12:25 PM

VISA Read over USB Problem: After a while the xBFFF0015 Timeout Error occurred

Hi,
I have trouble using labview with my non-NI USB device:
The device is an analog input DAQ board. I was able to setup communication with the board using a VISA driver specifically created for this board and direct FW calls using the product's firmware specification provided by the manufacturer.
This method has been working pretty good so far, but when I try to get large amount of data (64k samples @100ksps), the VISA Read returns the 'VISA: (Hex 0xBFFF0015) Timeout expired before operation completed.' error.
Please see the attached screenshot of the block diagram for details.
First, an 'analog input scan start' command is sent to the DAQ device, and then the vi tries to read all collected data from the device, once the right amount of data retrieved, or no more data is available the data collecting process (the while loop) ends and an 'analog input scan stop' command is sent to the DAQ device.
The data collection starts with no problem, but after a while, in loop# 400, the VISA Read hangs and then returns the error mentioned above.
I tried to increase the time out value, but it didn't help, the error occurred after the same number of loops, the VISA Read got hosed and the error occurred after the longer timeout expired.
I also tried to add some delays in the loop, but it didn't help either.
I am not sure what do I miss here and I would highly appreciate if anyone could give me some guidance how to solve this issue.
Thanks,
John
Attachments:
usb-read.png ‏18 KB

I just wanted to specify that this is not an NI board avoiding to make people think this is a hardware issue. And I think that the rest of the code is irrelevant in this case.
I believe that I don't use the VISA functions correctly. I assumed that someone who used these functions before would be able to point out the obvious steps missing in the data collecting process using the VISA functions.

Windows XP connecting Peer-to-Peer to Windows 7 with HP LJ 4000 through USB-2-Parallel port

I am running a Peer-to-Peer network and cannot connect my Windows XP computer over the network the 'quasi-server' running Windows 7 that has a connected HP LaserJet 4000 printer connected via a USB-2-Parallel port. The HP LJ4000 works just fine from the Windows 7 box (and serves ONLY as a backup printer) but connecting from either Windows XP PRO boxes will not work.
I have tried opening the Windows 7 Printers window and then updating the printer drivers, like it says it will, and that fails as well.
ANY suggestions would be appreciated!
Thank you,
Brett W. Sabio
Regards,
Brett W. Sabio, CPA-PFA

Hi,
You need something like this:
http://www.shopbot.com.au/pp-belkin-usb-parallel-printer-adapter-f5u002-price-106075.html
Regards.
BH
**Click the KUDOS thumb up on the left to say 'Thanks'**
Make it easier for other people to find solutions by marking a Reply 'Accept as Solution' if it solves your problem.

Is it possible to communicate with two different devices using two seperate serial ports in the same labview program?

The two bits of the program will talk to each instrument successfully if the other part of the program is not running. i do not need them to communicte with both serial ports at the exact same time, just within the same program, one after the other. i am using labview 6. any ideas of what i could be doing wrong?

Hello,
If you are using the Legacy serial VIs, you should really switch to the VISA VIs. Also make sure you are opening a session to each of the com ports at the beginning of the program and closing each at the end of the program. Problems can arise if your try to open a session to a port that already has a session open. Also you should update LabVIEW to 6.0.2
If you are still having problems post the error code and error message you are getting.
Ray K
NI Applications Engineer

Reading ascii codes from serial port and plotting them

Hello
I am trying to build a VI that reads data (ascii values) from the serial port.
I am trying to build a wireless phonocardiogram. I have a microphone that acquires heart sounds. these signals are amplified and sent to a A/D converter to digitize them. the digital signal are sent to a base unit. The digitals signals received at the base unit have to be sent to a computer (over a serial port to view them).
I would like build a VI to plot ascii data received over the serial port.
I would like to plot those values so that the plot just looks like a analog signal (the one I had before A/D conversion).
Can anyone provide me some help?
Thanks in advance.....
Solved!
Go to Solution.

Hi chaitu209
What is your transmission speed, samplerate, and bandwidth needed in your project? The bandwidth of the serial port is somewhat limited. Let me give you an example
Say you are using 115200 Kbit per second as transmission speed, one start bit/stop bit and parity bit, and 8 bit data. This will give you 115200/11 bytes pr second as the maximum theoretical transfer rate/sample rate. But if you are using up to 16 bit AD your maximum samplerate will be 115200/(2x11). So my advise to you is to use a binary transfer protocol not ASCII based protocol. This is not a problem in Labview with serial transmission.
Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)

How to configure visa to adquire dat from serial port and then converted to numeric value from a home embedded device

I already stablish communication with my serial port using VISA, selecting COM1 as the resoure name.
After that, I tried to read the data from the port (as we know the data was in string format )but I need to convert the data to numeric value to hadle it (no arrays).
Another main thing is that I'm develoing a new based Embedded design and tthe info that will trhow out from the device to the PC is binary.
How can I solved the problem, and if I want to make bidirectional communication with my system how can I do it? The VISA intructions as *IDN? and so forthetc can be recognize by the external system if the COM1 port is recognized by NI Max as ADSRL1::I
NSTR1?

Hello,
For an example of bidirectional serial communication in LabVIEW, please see the shipping example LabVIEW <-> Serial.vi. This can be found from LabVIEW by going to Help >> Find Examples. From the example finder, select Hardware Input and Output >> Serial >> LabVIEW <-> Serial.vi.
Once you are able to read the string data in, you can use the VIs in the String/Number Conversion palette to convert the data to numeric format. To access these, right-click on the block diagram >> All Functions >> String >> String/Number Conversion.
Let me know if this does not help.
Regards,
Sean C.
Applications Engineer
National Instruments

USB to Serial port delay

I have some LabVIEW code that communicates with a TI MSP430 development board via a USB serial port simulator. The hardware that does the serial to USB conversion is part of the development board. how the application works is the LabVIEW code sends a request using the VISA write VI, and the board responds. The requests and responses are both about 5-6 bytes each, and are being sent at 115200 baud 8-N-1.
Everything works, but there is a roughly 600ms delay between sending the request and receiving the first byte of the response. After the first byte is received, the other bytes are received within 1 ms. I assumed the firmware in the develoment board was slow, but I put a scope on the RX and TX lines coming out of the microcontroller, and the firmware responds in less than 1 ms, so the microcontroller isn't the issue. So somewhere between the UART to USB hardware, and LabVIEW, there is a 600ms delay. I have a feeling that it is the TI development board, or drivers that are holding things up. The USB to serial stuff seems to be kind of flaky generally on these boards. However, I wanted to come on here, and see if anyone had any ideas about how I might figure this out, or what might be wrong. I'm going to post on the TI forums also, and see if I get a resonse there.
Has anyone seen an issue like this before using USB to serial converters?
Is there something else I could try to narrow down where the issue is, or rule out some part of the system (like making sure that it isn't an issue with the VISA drivers)?

Jeff·Þ·Bohrer wrote:
What is the USB-Serial chipset?
The FTDI drivers offer some latentcy optimizations. Others do not.
Most TI MSP430 boards have their own build in USB interface based on the TUSB3410 from TI and the according driver for it is the TUSBWINVCP package. Nothing to do with FTDI.
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

USB to serial port

Hi all,
I am working on a VI to acquire data external to computer. The data is
being acquired via the serial port of the computer. When i first built
the software in labview , i tried it in my desktop( which had serial port) and it
worked fine, i was also able to generate messages in labview and send
it serially out.
However now i tried it in my laptop which didnt have serial port. So i
bought a USB to serial adapter. I can see the data from the in hyperterminal. But i cant get labview
to work with the simulated serial port. Labview doesnt display the
readings and gives an error: "unknown system error". I cant figure out
why, there must be no mistake in the labview program as it works fine
in my desktop, and also no mistake in the data being sent cause i can
see it in the hyperterminal window in the proper format.
Please help.
Thank you.

No, I am using Windows Xp only, however it has started to work today when i again tried, I do not know why!, but thank you all for your replies, i should have posted my query after testing it thoroughly. My apologies.
vinay
Message Edited by raybuzz on 07-27-2009 05:58 AM

Problem resetting count on read with fp ctr-500 counter

Using the ctr-500 module with a FP-1000. I want to reset the count of a channel on each read. The CTR-500 manual says to selecting "Reset on Read" from the Value menu. I've done that but the counter never resets when I read it. I then tried clicking on "Creat item" under channel attributes in MAX. It creates an item called "Read Reset Mode @Count Input 0" under Data Neighborhood. Added that item to the program and wrote to it with both a 1 and 0, but when I read channel 0 it still will not reset. Obviously, I'm missing something. I would appreciate any help or a simple example so I can get this resolved. Thanks, Mike
Message Edited by mike72903 on 01-31-2008 10:51 AM
Attachments:
reset count1.vi ‏15 KB

Found an example. Thanks anyway

Problems with asynchronous visa read with USB to serial port adapter

Similar Messages

Maybe you are looking for