GPIB vs COM-port=program stall...

I've made a program which use the com-port to read data from a test object. This serial reader execute continiously. At the same time I use the GPIB to control a switch/control unit.This causes the program to halt.If I then toggle between the front panel and the diagram
the execution continue. Can anybody tell me what cause this problem, can it be due to an IRQ
conflict or something........?

Hi,
I typically have this kind of application. A temperature-chamber is connected to
COM-port and controlled. In parallel there are GPIB-Instruments under control - like
power supply & multimeters.
But your problem is like finding a black cat in the dark.
Send your program as .llb (zip) to [email protected] - I try to do my best.......
Regards
wha

Similar Messages

How do I get LabVIEW to recognise a Gaussmeter as a device through COM port 1?

Hello everyone.
I am trying to do display the readings from a GM05 Gaussmeter in LabVIEW through COM Port 1 on my computer. I have installed the relevant drivers and MAX recognises that something is plugged in by listing COM 1, COM 2 and LPT 1 under devices, but it does not recognise the Gaussmeter as a device (it does not say 'device #' in brackets next to COM 1).. Therefore when I come to create a new Virtual Channel in the Data Neighbourhood I cannot select my COM port as a device. Can anyone help me to solve this problem, any advice would be greatly appreciated.
Regards,
Rob.

Unlike GPIB the com port or serial communication usually does not have an identify query, so it wont auto recognize the device. You should look in the manual of the device and send an appropriate string (there might be a self-test or identify string) and check for the correct response. Not all devices communicate both ways (some are talkers, some are listeners and many are both).
Paul
Paul Falkenstein
Coleman Technologies Inc.
CLA, CPI, AIA-Vision
Labview 4.0- 2013, RT, Vision, FPGA

Write among COM ports in the same PC without cables

How can I write to the memory address(es) of a serial COM port? I would like to send data from one serial COM port to another in a manner similar to the that of the 'Simple Data Client' and 'Simple Data Server' vi examples. This must sound strange since this is exactly what a null modem cable will do, externally. I would like to eliminate the cable connection between COM ports that exsit in the same PC and communicate between them, internal to the PC, somehow.
Currently, I am using a LabVIEW vi to read a serial message on COM1, translate it, send the trsanslation out on COM2, so that a separate windows program (no .DLLs to interface with LabVIEW) can read the message on COM 3. COM 2 and COM 3 are connected by a null-modem cable. This requires three COM ports, and two serial cables. I realize that I can use a physical loop-back jumper on COM2, for instance, where I send and read the translated message on COM2, but I still wonder if there is a method for doing this in memory, or something. Is there a way to accomplish the same objective with one cable (into COM1), no loop-back jumpers, and only two serial ports? In summary, I want to read on COM 1, translate in LabVIEW, then write directly to another COM port, internally, without using a serial cable. Can the 'IN PORT' or 'OUT PORT' vi's apply here? Are these tools only for parallel ports?
Hope this is not too confusing.... It seems like I am always trying to do something with LabVIEW that was not meant to be done....
Thanks.

Thank you. If I pay the price they ask, this looks like it will create and share virtual COM ports - exactly what I need. However, I would really like to find a way to do this in LabVIEW, such that I do not have to make my application dependent on another piece of third party software. The 'Simple Data Client.vi' and 'Simple Data Server.vi', included in the shipset examples, seem to do this for TCP/ IP ports. I wonder why the COM ports cannot be addressed at the memory level, in a similar manner???

How to use shared variables to address multiple Watlow controllers on the same COM port

Hello,
I am trying to use LabVIEW 2010 to control 4 Watlow temperature controllers on one COM port. 3 are Model 96 and 1 is an EZ zone controller. Each controller has a unique modbus address, and I am trying to read from and write to individual registers (such as closed loop setpoint) using shared variables. I am getting return data when reading (although the data appears to be invalid), but am unable to change the value in the register by writing. How can I be sure that the Modbus server is sending commands to the correct controller?
Chuck
Solved!
Go to Solution.

Peter,
Thanks for the reply. I have actually solved that problem. I realized that the Modbus server address has to be the same as the controller's Modbus address.
I have, however, run into another problem. Perhaps you could help me with that. I have a system with 4 Watlow controllers, 3 are series 96 controllers, one is PID only and 2 are ramping. The 4th controller is an EZ zone. I am using RS485 for communications and the controllers are all wired in parallel for communications and power.
I have set up 2 Modbus servers for 2 of the controllers.
This is the first I have ever worked with Modbus based communications. I have successfully programmed using the Modbus read/write VIs, and am wanting to move to shared variables. My questions right now revolve around addressing, Modbus I/O servers and COM ports. Specifically, at this point, I know the addresses need to match up between the server and the slave device (Watlow controller in my case), how many servers can I create and use on one COM port? If the number is limited, is there a way I can specify an address that I want the server to talk to? Will the broadcast mode work to request data values from the controllers?
I'd appreciate any information you can help me with, or if you could point me to some sort of concise 'How-To' for Modbus communication.
Thanks.
Chuck

HyperTerminal sees a COM port but VISA does not

It should not be possible that HyperTerminal sees a COM port but VISA does not. Does anyone know why or have any ideas?
Here's some more info: I wrote a LabView (LV) program and deployed it (via the Application Builder) to some of our production department's PCs (some Windows XP and some Windows 7). We use it to set up products we design and manufacture through our device's USB serial port. The USB port is actually a virtual COM port (VCP) - a USB to Serial converter or "bridge". We have a custom driver for our device and since each device's USB bridge chip is programmed with a different serial number, every time we connect a new device to the PC the installer runs and assigns a new COM port number. This is so our customers can use multiple devices on a PC. Fine. On one of our production PC's we were close to COM900 ports (HyperTerminal sees only up to COM256) when suddenly Win7 would not allow any more. We were able to uninstall orphaned (non-present) COM ports from DeviceManager ("DM") by starting it from a command console (DOS window) with a special command-line switch, "set devmgr_show_nonpresent_devices=1" then "start devmgmt.msc" (I have this in a batch file). In DM View menu you can "Show hidden devices" and uninstall them as if they were connected. I've also tried uninstalling them the normal way when the device was actually connected. Either way, sometimes, not always, depending on the COM port number, after reusing that port number by installing a new device which picks up that old, freed-up number, LV VISA doesn't see it. In other words, when "Refresh" is clicked in the COM port VISA list box, any new devices installed should be and normally are seen. (Refresh is not needed if the application is started after the device's driver is installed. It is only need if the LV application is open with the new device is added.) However, HyperTerminal does see it and lists it in the Properties screen, the "Connect using..." list box. And the port works with HyperTerminal. (Of course we've tried rebooting after uninstalling and/or reinstalling the device, with the same results.)
When I've spoken to the NI Applications Engineers in the past about serial port issues (not about this problem) they have confirmed that if HyperTerminal can see the port then NI VISA should also see it. This is crazy. I am posting this in hope that someone can shed some light on this problem.
Thank you. -Ed

Good catch. Yes, we're using the Silicon Labs CP2102 and have created a "custom driver" installation package. Our new PCBs have a factory-programmed chip, so the PC reuses that COM port (COM3 on that PC). The problem is when we we re-program the CP2102 (setIDs exe) with our PID, and device strings (including the S/N), the PC runs our installer and assigns the next COM port number. I was hoping that maybe it would go up to 64K or something! Anyway, it surpassed COM256 but we ran into this problem when almost up to COM900.)
There is a registry entry for each SN device, which shows the assigned port. If we delete the key with regedit, the COM port database (don't know the file name) still has the port number. That's where Device Manager comes in. It seems to allow us to manually delete the ports, but it would take quite a while to delete 900. (I was trying to make a batch file for DevCon, but couldn't get it to see the HW ID of the devices in need of deletion.) So we tried manually deleting a few. After doing that Device Manager shows that Windows (and HyperTerminal) can reuse the port number when a new device (new SN) is installed, but, as you know from this post, VISA cannot see unless I manually add it in MAX.
I can't see how it has anything to do with the Silicon Labs driver. I might have to delete ALL of MY devices, then uninstall the driver files, reboot, then reinstall, as you suggested with the SiLabs driver. However, I don't see how VISA will now see these changes. VISA must have it's own database. That's what I thought deleting the ports in MAX would clear out, like a fresh install, but apparently not.
I've been through Silicon Labs' tech support on other issues and they've been able to help on some. I could run this by them.
BTW, have you noticed that Silicon Labs' chip and driver, while faster than NI's own "bridge" or serial-USB converter (I returned it because at $100 it's performance was worse than a $20 converter you can buy in Staples), is substantially slower than a real serial port? For example, our device can transmit 250 readings per second (a 12 byte string). A real serial port used with my LabView program can keep up, i.e.., graph & tabulate at that rate, but with a VCP we only get about 70 RPS. Same code. Can't figure this one out. They say the've tested the driver to 900 KB claimed. We're using 115KB here. Anyway, the VCP driver makes it look like a COM port which LV thinks it is. Why is it slower than a real port when the USB should be able to work almost 10 times faster than I'm using it (up to 1024 bytes per mSec per the full-speed USB spec, which SiLabs claims they verified)?
Anyway, I appreciate your help. Thanks! -Ed

COM port are not shown in my application

Hello,
there is a reason why com ports are not shown on a Xp Embedded Touch Panel?
I have to communicate through a serial port in my application but com ports are not shown in Visa Resource Name control ...
I have included all VISA related things in additional installer ...
Solved!
Go to Solution.

Ok, i checked functionality of COM ports with a non-National Instruments programs and all it's working. Only Labview apps cannot see them.
On another PC where the Labview app works if i look at installed Programs in NATIONAL INSTRUMENTS section i can see:
NI VISA RUN TIME 5.1.0
NI VISA 4.5 for Labview on Windows Mobile/CE
On the machine where there the problem under National Instruments SW i can see only:
NI system components
but i've added in additional installer section of the app installer all VISA related stuff...

Why is my com port missing from my list of VISA devices

Hello all,
I have an Agilent E5810 ethernet to GPIB gateway. I installed Agilent IO library and chose to make Agilent my primary VISA because otherwise the devices on the gateway didn't show up in my VISA device list. Now all of my GPIB devices show up (local and via gateway) but my com port is missing. The com port is actually a USB to serial adapter. It shows up in device manager as CP2101 uart interface COM6. I reloaded NI-VISA but COM6 still oesn't show up. I reloaded Agilent IO and unchecked "make Agelent primary VISA" but that didn't fix it. It is also missing from MAX. I added COM6 ASRL6 but VISA doesn't see it
I think the root of my problem is getting Agilent VISA and NI VISA to work together but why won't my com port show up?
Thanks alot

Hello,
Can you please follow the steps outlined in the following forum post and reinstall NI-VISA and Agilent VISA?
Problem with NI VISA and Agilent VISA
If the problem still exists, please call 1-866-275-6964 and reference your call to your service request number (1194753).
Thank you,
Simran K
National Instruments
Applications Engineer

Output to com port

hi,
pls i'll like to know how i can get my program to sent bytes to the com port of my computer system. I suppose there should be something in the java.io package

Nope !! there is no option in java.io package.
You have a package by name javax.comm which will let you to read/write data to any desired port.
Download it from sun's site along with the required .dll file.
Hope this helps !!

HTML DB and Serial(COM) Port

Hi, everyone,
Is there any way that HTML DB can communicate with Serial Port (COM Port) directly? I searched the forum, and saw someone mentioned "Visual Baisc", "Javascript", "ActiveX", or "DLL". Could anyone give an example for it if you had successful experiences about it?
My problem is I'm working on a HTML DB project which will read data from barcode scanner. And request I have is the HTML DB can monintor the Serial Port and read the data from there if there is one. That means some programs need to be embedded in or called in HTML DB page. I known there are some commerial software developed for this purpose on the market, but I am wondering if it can be done by HTML DB itself?
Thank you. And Regards,
Ran

> Is there any way that HTML DB can communicate with Serial Port (COM Port)
directly?
There seems to be a misunderstanding or lack of understanding about what APEX/HTMLDB is ito client-server architecture.
APEX is a server side application. It resides entirely in Oracle as PL/SQL software. It is executed by Oracle server processes that are servicing requests from a web (i.e. Apache) server.
APEX does not "run" on the client. APEX streams, via the web server, data to the client browser. These MIME streams can be anything from HTML, XML, plain text (like CSV data), to images and so on.
The browser receives this data stream, and depending on the browser configuration, does something with it - e.g. it renders a HTML data stream, it starts Flash Player plugin for a Flash graph, etc.
The browser interacts with the client. With the user, the mouse, the keyboard, the printer and any other peripherals the client may have - like a barcode scanner.
Can HTMDBL use a COM port? The more correct question is, Can PL/SQL in the Oracle Server Process access the COM port of the Oracle Server Platform?. The answer to that is yes - it can be done.
But in the context of client interaction and the COM port being that of the client platform - no. PL/SQL is a server-side language. It does not execute on the client in the client browser.
It is important to understand the web client-server architecture - as it is a lot more complex and inflexible and slower than the "traditional" client-server architecture. It is stateless. It uses a very "primitive" client, the web browser. It is bound to W3C standards which is the lowest common denominator. Forget about smooth and slick client GUIs using and supporting the latest desktop GUIs standards and controls. Forget about easily interfacing with the client platform's file system and peripherals and so on.

Need a gui to send simple ascii commands to com port

I am not a programmer. Several years ago I took a class in Java. Now, I am looking for a gui with buttons that are programmed so that when clicked on with mouse a command (ascii or hex) will be sent to the com port. I am pretty sure that I don't want to read from the port. I have a table of commands that I want to match up to some buttons - a simple way of putting it.

Before you embark on Swing and javax.comm, I'd encourage you to get up to speed with basic Java. A lot has changed in the past couple of years, and getting some practice with the basics will save you a great deal of frustration. Here are some recommended resources:
Installation Notes - JDK 5.0 Microsoft Windows (32-bit)
Your First Cup of Java
The Java� Tutorial - A practical guide for programmers
The Java� Tutorial - Trail: Learning the Java Language
New to Java Center
Java Programming Notes - Fred Swartz
How To Think Like A Computer Scientist
Introduction to Computer Science using Java
The Java Developers Almanac 1.4
Object-Oriented Programming Concepts
Object-oriented language basics
Don't Fear the OOP
Books:
The Java Programming Language - 4th Edition
Head First Java, by Bert Bates and Kathy Sierra
Thinking in Java (Free online), by Bruce Eckel
Core Java, by Cay Horstmann and Gary Cornell
Effective Java, by Joshua Bloch
Let us know if you have specific questions. Good luck!

Streaming Audio over serial com port

I have a task where I am programming a robotic system and control unit. I am using a laptop for the control unit. On the laptop is a microphone. What I would like to do is capture the audio from the microphone and transmit this via the radio to the robot to play on a speaker. The radio plugs into the com port on the laptop. I can transfer a .wav file by using the Flatten to String.vi send and unFlatten on the other side. What I need to do is stream the audio as it is collected from the microphone. Is this possible? If so, any suggestions would be appreciated.

It will depend on the speed you are using and the resolution. Let me give an example. Say you are using 1 start bit one stop bit and 8 bit data. This mean for each byte you have to send 10 bit. Given that you are using 16 bit for audio and a 115200 rs232 link the maximum sample speed will be 115200/20 equal to 7760 samples pr second. But I guess your actual max speed will be lower. If you only need 8 bit sound you may get higher data rates. That is perhaps the reason for the strange voice on robots in motion pictures
Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)

VISA "Find" not seeing COM port but Win7 sees it

Allo. I'm trying to communicate via virtual com ports with a device with an FTDI chip. The device with the FTDI chip has both a USB type B port as well as a 9 pin dsub port, and I need to verify both ports work.
I'm using a laptop with Windows 7 and my program is in LV 2010. I have a Sabrent USB to serial cable to test the dsub port, and a standard USB cable to test the other port. I've installed the latest FTDI drivers and when I plug in both cables and look under Windows Device Manager, I will see both of them under unique COM port settings (usually COM4 and COM 5). So Windows sees and recognizes both virtual COM ports, and no yellow warnings.
However when I run the "VISA Find" function in LabView, it only sees COM5 (the Sabrent serial cable) but not the COM port using the USB type B cable. I send the results of the "VISA find" to a display and it will show other ports, like the parallel port, so I know it's seeing more than one port.
Any ideas why Windows can see the two COM ports but the "VISA Find" function can only see one? My guess is there's something with the FTDI driver set up.
Amateur programmer for over 10 years!

Yes, but its not for the faint of heart!
You can probably do what you want by using the refresh "F5" in MAX or add this token
[VISA-CONFIG]
ShowRegisteredDevOnly = 0
to C:\ProgramData\National Instruments\NIvisa\visaconfig.ini
Another thing to try is to recover the unused COM Port numbers each time you change the device. By default Windows will "Save" those previously connected COM port numbers an if it sees the device again it will re-assign the old number. This means that the COM number keeps getting larger and larger. At some point the PC's BIOS will say that's rediculous and you will experience trouble.
Programatically you could call
C:\Program Files\National Instruments\NI-Serial\NiPortConfig.exe to launch the same utility. there is probably even and unpublished switch to click just that one big button for you but I can't find it.
It looks like you may be running into some part of this known issue
Jeff

Not enough memory error when disconnecting device on a virtual com port

I maintain a large application that collects data from many data source channels (using coustom hardware read thru a conventional COM port) and I am adding a GPS data source on a USB port using a virtual COM port driver. The application runs 24/7/365 and works well including the GPS data, if undisturbed. However, the application needs to tolerate a physical disconnect and reconnect of the GPS device without user intervention. When I disconnect the GPS, the application becomes unresponsive most of the time (the mouse responds and other programs that are open on the desktop work fine). I abstracted the serial code and made a separate vi (below) for testing. When I disconnect the GPS from the COM port, I get a "Not enough memory to complete this operation" message 9 out of 10 times and the vi is unresponsive until I clear the error message (the tenth time it continues working). I built the vi this way to collect data continuously. I suspect that this is the problem with the full app but I don't see the Not enough memory message there and therefore the full app does not respond and must be terminated via Task Manager. The full app runs full screen mode.
The LV app runs on Windows XP and LabView 7.0 (the client doesn't want to upgrade).
I have tried probing the error message lines at all points in the vi but they don't show anything when the 'Not enough memory' message occurs (they show the expected device not found error after clearing the error message).
Any suggestions would be greatly appreciated,
Mel
Still learning LV......
Please post any code suggestions as graphics as I don't have access to any version of LabView newer than 7.0.
Attachments:
SerialPortRead.png ‏22 KB

Jeff·Þ·Bohrer wrote:
First, there likley WAS human intervention that caused the GPS device to be removed. That wont happen when you lock the device inside a cabinet with the rest of the test system. Physical access control first! If someone goes and mucks with your experiment setup while its running, that's a "poor Labratory procedure" not a "new software requirement"
I think he was meaning to say without user intervention on the software side.
I have seen odd behavior if you disconnect from a com port whilst LV still has the port open. There are a couple things I myself woud try, being the experimenting type that I am. Perhaps setting up a com port check to see if it has a valid connection before polling for data. If not then a blank case or some other generic code.
The issue with this would be if it became disconnected while LV was polling data. Hard to get around this condition. Is there a way that the cause of the of the connect/disconnect (whether human or otherwise) could be set up so that a signal can be sent to the controlling system (pre-disconnect and post-connect) to trigger an event to handle the software side? A simple signal switch or something. Just thinking out loud. Withoug knowing all the particulars, it's hard to make detailed recommendations.
Doug
"My only wish is that I am capable of learning each and every day until my last breath."

Program Stalls Briefly causing test rig damage

I am using LabView and a C-DAQ 9178 to control a hydraulic test rig. The C-DAq utilizes a USB connection to the host computer running Windows 7. The program is a closed loop setup utilizing a PID subroutine to control each of the hydraulic valves and pump. The control can be based on either cylinder position or load. I am using a 9219 module to read the load cells, position indicators, and valve spool position. A 9264 module takes care of the voltage outputs to the valves, relays, etc.The program will run great for extended periods of time (the machine is a fatigue tester, so it accumulates load cycles on a test sample over time). But every once in a while, it will miss. And by miss, I mean it stalls. The program is writing certain paramaters to a text file for review later. What we see is a major delay in the time component of the data file.
It will look something like this.
Time:
604.150
604.200
604.250
604.300
604.524
604.554
604.575
The problem with this delay is that if the test subject is fairly stiff, the program stalls, causing the valve to stop and stay in whatever position was it's last signal (normally open). This causes the cylinder to keep moving and normally results in unwanted damage of the test subject. The program has checks built into that will shutdown the pump, center the valves, release the load, and unload the system pressure if the cylinder moves out of a given position or force range. However, because the program stalls, these checks do not work until the program resumes and it is too late, the damage is done.
What can I do to eliminate this stalling problem? Any help is greatly appreciated.
Thanks
Adam Kuiken
Senior Test Engineer
Arctic Cat Inc.

First, you need to determine if this is a Windows problem, or if your LV code is responsible.
If your data files are large, and you are building the text file using inefficient LV methods, you may be making an unexpected call to the memory manager. This is just one possibility -- there may be others. (Restructuring the code, with the file save in an independent loop, may aleviate the issue to some extent.)
If you have eliminated the possibility of a LV-based problem, then Windows could very possibly be the culprit (as suggested by others in this thread). Windows optimization *might* get you there, but there is always some uncertainty if Windows is in the equation. In testing, it might appear to be fine, but then Windows decides to scan the DVD drive, and you experience the failure again.
Side Note: Back in the LV 2007/2008 days, I had a similar intermittent Windows problem. It appeared to be related to the DVD drive. The solution was simply to put a DVD disk into the DVD drive. This prevented Windows from scanning the drive at unexpected times, solving the problem.
If Windows system timing turns out to be the culprit, migrating to LV RT might be the easiest path forward. cRIO is a popular choice, but I personally prefer PXI or a desktop PC configured to run RT.
If your application doesn't require the user to engage other Windows applications (Excel, Word, etc), and additional hardware costs are the primary concern, one option is to configure your existing PC to run RT. This can be a cost-effective solution if there is some reluctance to purchasing additional cRIO or PXI hardware.
Here is a link to the requirements for running LV RT on a desktop PC:
http://www.ni.com/white-paper/8239/en/
We have successfully used LV RT on customized PC hardware when the application requirements exceeded the top-of-the line PXI controller, or when the cost for a capable PXI system has been prohibitive. In both of these situations, a custom LV RT PC makes good sense.
Anyway, good luck with your issue.
-- Dave
www.movimed.com - Custom Imaging Solutions

Exe com port error

Hello,
I am writing a program to pick com ports for the main program. The com ports are actually USB devices and I want them to be able to choose different ports if they happen to change because of the USB. So I wrote the program to populate a menu ring with the names of available com ports. Everything works fine as a vi, but when I built it as an exe the property node throws errors. I am running the exe on the same machine as my vi for testing.
# -1073807246
Property Node (arg 1) in pick comports.vi.
The property node is : Property:Interface Information:Interface Description
Using this as a VI it puts out names similar to what you would see in the windows device manager. The false case just puts the words "Not Used". The input is an array of Visa references for COM1 - COM10.
Any ideas on why it breaks in an EXE?
Solved!
Go to Solution.
Attachments:
error.png ‏6 KB

_Bryan wrote:
It would be nice if the search engine would have pulled up that page you linked to.
It does if you don't search in the forums only, but on the NI Website. The website search includes the forums, so it's usually a better place to start, especially if you have an error code/message then it might find some KB articles or similar in addition to forum posts.

GPIB vs COM-port=program stall...

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