Isolation Required with RS485 But Not Offered with High Performance?

[Gammatized]

I am looking into purchasing a PCI-8431/2, High Performance 2-Port Interface for PCI. I want "high throughput with minimal CPU usage." I am running a program that was created in LabWindows/CVI by a colleague. The program is slow (i.e. user interface update rate is very slow), and it is thought that this board will provide improvements. We are currently communicating through the PC's serial port through a 232/485 converter. Should I expect an improvement wiht this board?

The National Instruments pdf specification document for the PCI-8431/2 card has a long discussion about the benefits of isolation. However, the "high performance" cards don't have isolation as an option. Why is this? Should I expect problems because of this? What is recommended? I notice that the PCI-485l/2 card has both isolation AND LabVIEW Real Time support! Is this a better card?

I am new to this Real-Time, LabView, and LabWindows stuff. We have LabWindows. It appears that it also has "Real-Time." Our instrument/process control program does need to get feedback from instruments quickly, but not at spectrum analyzer speeds. Is "Real-Time" what I need? Is the "high performance" card going to give me what I need in performance?

[LuI]

Hi Speed Challange (or better High Speed challenge?),

in order to avoid some disappointments, you should first consider if the communication is the 'bottle neck' of your app. I do not know if your assumption about this is proven valid. You may want using NI-Spy or any other tool to check the real transfer rate of your app. You may as well estimate the data transfer rate between your device and your application.
There are at least two other possibel reasons for a slow response:
1. A high CPU load due to lots of calculations.
2. Non-optimal programming (one single thread polling UI AND ports AND doing calculations.

To try to answer your other Qs:
> ... "high performance" cards don't have isolation as an option. Why ...
Isolation uses some non-electrical transfer bridges, either optocouplers or transverters. Those have limited bandwidth and start becoming really expensive with higher bandwidth. 2Mbits is quite a high transfer rate for this.

> Is "Real-Time" what I need?
Depends. Real time means, that your app must react within a specified time frame under _any_ circumstances. This can not be proven using simple OS like Windows, because other apps can block or crash the OS. If your real-time needs are some seconds _and_ you have a kind of watchdog, than Win may as well be enough.
So to decide if you need a real-time solution does mean to decide what 'real-time' does mean for your app. You stated:
> ... need to get feedback from instruments quickly, but not at spectrum analyzer speeds ...
That's too vague.

You may want to ask the author of your current app for some more details about his program design and for the sources. You may need them when exchanging HW.

Sorry for this long winded and somehow vague answer, but your Q was too unspecific.

Greetimngs from Germany!
--
Uwe