Applies To:
  • CitectSCADA 3.xx, 4.xx, 5.xx

I have heard there are video cards which can drive two or more VGA monitors. Can you explain how Citect can be configured to display on multiple monitors, and what configurations are possible?

There are 3 common configurations:
  1. Display the same Citect screen on both monitors.
  2. Display completely different screens (e.g. alarm page and a graphic).
  3. Display the same screen developed as double wide, where 1 monitor shows the left side of the screen, and the other shows the right side of the screen.

All three are possible, but the most common is number 2. This has been done successfully with Citect a number of times. There are a couple of cases where this is a valid engineering solution, for example, where you want one page (such as an alarm page) to be displayed almost permanently on one monitor, and on the other monitor change pages as per usual.

However, most people who do this to save the cost of a PC and licence don't make the same mistake twice. It is more difficult and slower for operators to use a system set up in this fashion, and it easier to make mistakes by accidentally entering data into the wrong page.

It works as follows:

You install a Graphics Card and software into the PC which supports multiple monitors. This operates at the Windows level and has nothing to do with Citect - i.e.; all applications can use this. What you get is a desktop that is twice the size and covers both monitors (half on one monitor and half on the other). You can move the mouse between the two monitors almost as if it were one large monitor. This is a bit weird to the eye, so you should put the monitors as close together as possible and choose monitors that have narrow "borders". You can then build your project so that you can have two pages open at the same time, one on one monitor and one on the other. This is one reason why we have the Mode 0 on the WinNewAt() function. When you have a separate page (or Window) on each monitor and you want to enter data via the Keyboard, the user must put the page in focus, so that Windows knows which window to send the keyboard input to. This is a possible area for operator error - if the operator presses keys without putting the correct window in focus (via mouse or keyboard).