It should be noted that both RSLinx and Citect cannot operate at the same time as the board drivers will try to access the same hardware at the same time and cause problems.

In some cases Citect can be made to work after RSLinx has been started and shutdown. i.e. 

1. Startup RSLinx.

2. Confirm the PKTX card is operating.

3. Shutdown RSLinx.

4. Startup Citect and follow the dialog boxes to make Citect start up completely (there will be no communications at this stage).

5. Shutdown Citect and then restart Citect (without rebooting the machine). At this stage Citect may now communicate via the PKTX card. Shutting down and restarting Citect will still result in communications working.  However, if the machine is rebooted, it will no longer work unless RSLinx is run initially.

The way to overcome this is to enter the computer's CMOS setup and find the setting for 'PnP operating system' (Plug and Play) and change it to 'no'.

The reason this error occurs is due to a bug in the PCI 9050 chip on the card where certain addresses will not work. If the computer's PnP BIOS assigns one of these addresses to the card then it will not operate correctly. RSLinx can detect if one of these addresses has been assigned to the card and automatically change it. However without the PnP OS disabled in the BIOS, the next time the system is rebooted the address will be reassigned back to the wrong one.

The bug in the 9050 chip is documented in errata 9050-SIL-ER-P0-1.3 at:

http://www.plxtech.com/download/9050/errata/9050errata-13.pdf

Citect has confirmed this to be a problem. We are researching this problem and will post new information here as it becomes available.