Commands to FTDI virtual COM port via NI VISA interfere with communication with FTDI chip using D2XX drivers

Hello!
I am trying to communicate with a DLP Design module DLP-USB1232H which uses an FTDI chip. My program uses the D2XX drivers. It works, but...
In another program that runs at the same time, I'm communicating with another instrument via a virtual COM port (VCP) that uses an FTDI UART. In this program, I use the VISA Serial Port functions. It works, too, but...
The first program has the capability of listing all the FTDI devices in the system prior to choosing the right one to communicate with. When the VCP is plugged in, it lists it (FT232R USB UART) along with the DLP-USB1232H and communication with the latter device works. But as soon as the second program sends a command through the VCP, the first program no longer "sees" any FTDI device. It stops working.
I have tried 2 different FTDI VCPs; one a standalone cable and the other built in to the instrument.
I’m using Windows 7 32-bit. My programs are both LabVIEW 8.5 executables.
Is VISA "taking over" the channel to the DLP-USB1232H? Does someone who understands NI's implementation of VISA have any ideas on why VISA is doing this? Or if something else is going on?
I'm also interested in workaround ideas. I've tried a "Prolific" VCP, but most drivers don't work and the one that doesn't give an error in Device Manager doesn't communicate with the instrument.
Cheers
Halden
Solved!
Go to Solution.

Halden,
It really sounds like you have a resource conflict. That occurs when two programs or parts of programs try to use the same device or port at the same time. Your Get Device Function probably tries to open a session with each port (as you increment the index). When it hits a port which is being used by the other driver, it cannot open the session and stops working? Have you examined the errors returned by each program? The VISA drivers will return an error when the port is in use. I do not know about your program or drivers, but I would expect some kind of error. Automatic error handling in LabVIEW will not catch errors from a driver if it does not translate them to LV error clusters. So do not count on automatic error handling, if you use it, to display all possible errors.
Lynn

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I am using an FTDI chip to go from USB to serial communication (FTDI Driver: 2.06.00). It seems to work at first but then after some time the connection gets lost ("connection for the given session has been lost" or "I/O error"). This happens in MAX as well as the built executable of the program I am running. Latest VISA drivers are installed - 4.6. I have tried flushing the buffer before and after communication with both visa clear and visa buffer flush vis. The lost connection seems to happen randomly.
I have seen other threads about this issue but they never reach a resolution. One thing i notice is that there are two FTDI devices in this system and only one fails, however when I unplug the working device the one that fails is able to connect again.
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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.
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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.
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I install BS from Toshiba and it seems ok. Bt ir desn´t work. I see all the drivers installed, system devices, etc. No Toshiba BT ports can be seen. Local com ports only show modem port. Try to create a virtual port but get a message "unable to create a bluetooh virtual port" I have a satellite m100-145. Can anyone help on this ?
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Thx for your suport.
I decide to reinstall windows and all software. Now it works.
The error was due to the fact that if you have BS from Microsoft (called bluetooth monitor) and you install the BS from Toshiba after that, even if you remove the BS from MS, the BS from Tos is unable to create the virtual com ports (except modem).
I try with the latest version of BS and the problem was not solved. So if there is a previous installation of BS fom MS the BS from Tos get the message of "unable to create the bluetooth virtual com port".
Now i fixed reinstalling SO from beginning.

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Hello,
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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.)
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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)?
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VISA "Find" not seeing COM port but Win7 sees it

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Yes, but its not for the faint of heart!
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[VISA-CONFIG]
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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
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Using VISA can not find the com port

I use visa read but can't find any com port in Windows 7.
How can i find the com port in Windows 7??
由 jw2002 在 06-28-2009 09:20 AM
上編輯的訊息
由 jw2002 在 06-28-2009 09:20 AM
上編輯的訊息
Solved!
Go to Solution.

Windows 7 is not officially supported by National Instruments as it hasn't even been released. That means you won't get any official support from NI on this.
That said, does your computer actually recognize a serial port? Do you have an actual serial port, or do you have some sort of virtual COM port, or are you using some sort of adapter, such as a USB to serial port box? If it's any of the latter, the most likely reason is a driver issue which needs to be written to be compatible with Windows 7.

Commands to FTDI virtual COM port via NI VISA interfere with communication with FTDI chip using D2XX drivers

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