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

It has been found that not all new PCs are compatible with SQUARE-D SY/LINK cards. This is because of differences in the implementation of the ISA bus between SY/LINK cards and some newer PCs.  An incompatible combination will result in errors being generated when used with the Citect SQUARE-D driver. For example, the SQUARE-D "illegal opcode" error may occur regularly under these conditions. How can the compatibility of the PC be tested? 

Before committing to a specific PC platform, compatibility must be tested using a SY/LINK card, the PC, a SQUARE-D PLC and NIM (Network Interface Module). A free software test utility, developed by Schneider, is available from the Citect FTP site. This software can be used to confirm SY/LINK operation with a given PC. In general, if the PC BIOS allows full control over ROM-shadowing, ISA bus speed and RAM wait-states, it is usually possible to configure it to work successfully - but this is by no means guaranteed!  Please note that some motherboard models may be compatible, while others are not, even if they are from the same PC manufacturer.