I am connecting an Agilent VXI plugNplay (using VISA on W2000 and programming in VC++) to a VME Chassis (with two PRO-1900 boards) using a MXI-2 bus. I'd like to use TCP to send data from the VXI/VISA system and the boards in the VME chassis. The documentation I've read seems to indicate that the TCP can only be done through the ethernet connection. Is there a way to identity a VME resource to allow me to use it as TCP::INSTR or even TCP::SOCKET ?
It seems that you want to access your VXI/VME intruments remotely via ethernet. If this is the case, I would recommend you to control your VXI/VME system using "Remote VISA". Remote VISA is first implemented in NI-VISA version 2.6, and is supported under all Win32 Operating Systems and Linux x86, both for Client and Server. There are two ways of implementing this system (see image in PPT file attached below): 1) Use a PC with an ethernet port and with a PCI-MXI-2 board connected to a VXI/VME-MXI-2 board. Connect to the PC through the network. 2) Use a VXIpc Embedded Controller in your VXI chassis and daysichain to other chassis using a MXI-2 extender. In both cases you will use a VISA Instrument Descriptor of the form "visa://machinex/GPIB0::2::INSTR", without the quotes. For more information on how to use Remote VISA see the tutorial linked below: Tutorial: Remote Instrument Control with NI-VISA
Remeber that the MXI-2 interface allows you to control your VXI/VME chassis from a PC, and when used between two chassis, it extends the VXI bus. So the MXI-2 extender allows you to control your VXI/VME chassis as if you had an embedded controller in the chassis. You will communicate with your boards the same way that you would if you had an embedded controller in the chassis, in other words, the MXI-2 extender allows you to expand your VXI/VME chassis and makes the extensions totally transparent to you.
The VXI/VME-MXI-2 extenders are not based on ethernet technology. They do not have an ethernet port and, therefore, they do not need to store an IP address or support the TCP/IP protocol.
Now, if you want to communicate with a specific VXI/VME instrument using ethernet, you need for that instrument to have an IP address and a connection to the network. This is, the VXI/VME instrument has to have the capability of storing an IP address and use the TCP/IP prtotocol to read and write to the ethernet port.
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Hope this helps,
Claudia Lorente Applications Engineer National Instruments http://www.ni.com/ask