how many serial ports are supported by VISA,W2k,LV7.1?

[Henrik_Volkers]

I'm planning to poll data at low rates from a lot of serial ports with VISA (W2k,LV7.1). If I use Enet2Rs232 moduls, how many sessions can I run simultanius?
What will limit the number of ports? OS?VISA?

In the past I had stability problems with opening and closing VISA (2.6) serial ports.

[Dan_Mondrik]

Henrik:

NI-VISA can handle up to 256 COM ports, and the default limit in NI-VISA is to allow up to 256 sessions opened at once. We've had plenty of customers using 32 ports simultaneously; I'm not sure if anyone has tried more.

The limit should not matter regardless of whether it is a PCI, ENET, or other type of Serial controller, although there may be slightly stricter system limitations on the number of TCPIP connections you can have active at a time. But we haven't pushed it to the limit to find out for sure.

NI-VISA 3.1 has improved both robustness and performance for Serial. You might want to give it a try.

Dan Mondrik
National Instruments