Applies To:
  • CitectSCADA 1.x 2.x 3.x 4.x

Problems with network cards can be caused by bad network drivers. We have had quite a few problems with low cost network cards or buggy drivers over the last few years. Bad network cards can cause system crashes or Windows to hang. These problems may take many days or weeks to show up and are very difficult to fault find. I don't recommend you try and save money on your network cards. Today network cards are very inexpensive and they are a vital part of you Citect system. 

I only recommend using Genuine Novell NE2000 Ethernet cards. They are the only cards I will accept here at Ci Technologies. Even if the computer has built in network card on the mother board, I disable it and install a NE2000 card. So I normally avoid buying computers with built in network cards as I will never use them.


If you have a problem with a network card it is usually very difficult to find it. You may find that Windows will just hang (stop responding), crash out to the DOS prompt or cause a EMM386 Exception error. The crash will most likely occur randomly from hours to several weeks after starting the computer. This makes tracing the problem very difficult.

The failure is normally not caused by the hardware of the network card as most network cards use standard chip sets which are quite reliable. It is more likely to be caused by faulty device drivers. This is especially true of network cards on the mother board as they tend to be special designs and require unique drivers.

Network cards are very inexpensive. They are so inexpensive that you should not waste money buying low cost ones. If you have to spend several days or weeks searching for the reason for a crash you have just lost enough money to pay for all the network cards you can ever use in your lifetime. Not to mention the heartache it has caused you and our support centre.

If you use some fancy network cards and you upgrade your operating system there may not be a driver available. As Novell NE2000 and generic NE2000 cards are so common, every operating system has drivers for them. I have never seen and operating system which does not support them.

High performance cards tend not to increase system performance. Brand X may say they have some whiz bang network card which gives super performance etc. With Citect systems the network card is usually not the limit of performance. Most Citect systems run with low network bandwidth (typical 2-15%) as Citect is limited by PLC communication. So increasing the performance of the network card has little to no effect on the over all system. The only performance increase you can get is access to the file server, so the display of background images will be faster. If you Citect system is highly loaded then the limit will be on the 10M Ethernet. To increase performance use a switched hub or upgrade to 100M Ethernet.

You may find that network cards you have been using work OK for your general day to day use. However Citect is a much more demanding application and is required to run 24 hours a day 7 days a week. The network card which is OK for your general use may be restarted every day (so hide any long term problems) or your application may not be as demanding as Citect. There for you will feel your network card is OK while running with Citect it may fail.

See also Q1411 Q1449.

PS: I don't own shares in Novell or Microdyne (the makers of NE2000 cards) although red is my favourite colour.