RS-485 ports as COM ports

[Siddu 140]

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

[Chris_Rake]

RS-485 COM ports appear as standard COM ports (COM5, COM6, etc.) after installation. Are you looking for ways to make these ports show up as COM1 & COM2 or some other "standard"?

[Siddu 140]

Chris,
Can we make ports of a non NI RS485 card appear as standard COM ports?

Thanks,
siddu

[JLS]

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

[Siddu 140]

JLS,

I have a non NI card which supports all the serial protocols. The current driver does not make the ports appear as standard COM ports. Can you suggest me someway to make the ports of that card appear as COM ports so that they can be configurable using VISA through MAX.

Regards,
Siddu

[Chris_Rake]

Each serial card vendor should provide a driver that maps the COM ports as COM#. If you are having problems with 3rd party serial interfaces you may need to contact the device's manufacturer for additional technical support.

[Siddu 140]

Chris,

I do not face any problems with the driver provided by the vendor.But it would be of great use if the ports appear as standard COM ports for my applications.So i want to write an application program either in CVI or LabVIEW to make the ports appear as COM ports over that driver. Can you share some information in this regard.

Thanks,
Siddu

[Chris_Rake]

Having the ports show as COM# is entirely controlled by the serial port's driver. When you go in the device manager, do you see the other ports listed? If not, how do you use these ports in other applications?

[Siddu 140]

Chris,
The current driver gives me a memory mapping for the 4 channel card.So all the functions of the card( transmit, recieve) access these memory locations using viIn8/16/32 and viOut8/16/32 to perform the operations.These channels are not configured as ports and are not listed under device manager. So i am not able to use the VISA functions like viOpen,viRead which we normally use for serial COM ports.

Thanks,
Siddu

[Chris_Rake]

Ah - unfortunately it sounds like the serial "driver" really doesn't do much as the viIn/viOut functions are "register level programming" and basically you are writing your own driver at the application level.

In order for these COM ports to show up in Windows Device Manager you will need to contact the serial card's vendor for updated driver software that provides a Win32 API interface.