Applies To:
  • CitectSCADA 1.00, 1.01, 1.10, 1.11, 1.20, 2.00, 2.01
Summary:
If there is another peripheral card addressed in the same 128k boundary as a PC/Xi card, it must be a 16-bit card to work properly. Due to a limitation of the original PC design, you cannot mix 8-bit cards in the same 128k memory range of 16-bit cards. The AB-KT, Tiway and Square D cards are either 8 bit cards or not true 16-bit cards. Therefore, these cards would fail to operate correctly if placed in the 128k boundary of a PC/XI card. For example, a Square D card at memory CF00h would not work with a PC/Xi card at D000h.

Segments C000-DFFF are in one 128k block - any card in this range would clash with a PC/Xi card at address D000h. Segments E000-FFFF are in one 128k block - any card in this range would clash with a PC/Xi card at address E000h. 

Solution:
The PC/Xi card can be configured to a memory address above 1Mb. You should configure the PC/Xi board at address F9000h. This will stop it clashing with any boards below the 1Mb limit. Note that to put the PC/Xi board at this address, your computer must have less that 16Mb of RAM otherwise the memory will clash with the PC/Xi card. 
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