RS-485 ports as COM ports

The RS485 ports of RS485/4 PCI card from NI appear as standard COM ports.Can anyone share more information about how this can be done.
Thanks,
Siddu

Hello,
The COM ports on your computer should show up as standard COM ports, as do the NI serial ports. Other vendors of serial products, such as pci-serial products, should have drivers which make those ports appear as COM ports as well. There are differences between RS232 and RS485 serial protocols; you can read about this at:
http://zone.ni.com/devzone/devzoneweb.nsf/opendoc?openagent&14A5CB349BD18D20862568210005EB0A&cat=1485C1F3A7F1EF8D862567EC00577686
Hope this helps!
JLS
Best,
JLS
Sixclear

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NokiaComPortProblem.log ‏82 KB

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Some tips,
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c commands you used with HyperTerminal.
"sy" wrote in message news:[email protected]..
> Good question. In fact, I think the problem stems from how COM5 is
> mapped to my PC. As for the second question, I got the same I/O error
> when using MAX. I believe that there is a conflict between NI
> software and the software I use to map the RS485 line to COM5.
>
> I am using Advantech's ADAM 4570 module to convert a RS485 line to
> ethernet. The ethernet cable goes into the PC. A software utility is
> used to map the ethernet connection to COM5. It is conflict between
> this utility and NI. Any idea on how to resolve the conflict? Thank
> you.

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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???

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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.
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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.)
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Anyway, I appreciate your help. Thanks! -Ed

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Newbie : working with INTERRUPTS with SERIAL com port ?

hi guys !
here is the deal :
my app needs to
monitor a com port while doing something else
or to be interrupted when something is available on the com port.

Ive been trying to do something similar
so far I launch a new thread, which sets up a comcallback to trigger on
0x05 comming through the serial port (ENQ)
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Grahh!
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andy
jerry wrote in message
news:7sqnad$45u$[email protected]..
> hi guys !
>
> here is the deal :
>
> my app needs to
> monitor a com port while doing something else
> or to be interrupted when something is available on the com port.
>
>

RS-485 ports as COM ports

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