I have a problem with DH-485 communications. The comm keeps dropping out. It usually starts right back up, but after a few minutes I get the pop-up saying the communications were lost. Here is the overview:

PC is a WinBook running Win XP Pro SP2
Programs are RSLogix500, ver 7.00 (CPR 7)
RSLinx Classic Pro, ver 2.50 (CPR 7) running as a service

Communication is DH-485 via PCMK through the 1784-PCM/B card.

Many times I have to re-boot the PC to get back online, but this is no guarantee that it will stay on. AB rep says this is a glitch in the RSLinx but they give no solution. Last year we replaced the PCMK card and it still happens. When it is a critical operation I have to use the DF1-RS232 and connect directly to the PLC. This doesn't help when programming a PanelView.

I would appreciate any feedback. Has anyone else had theis problem ?

Have you been able to go online with this exact setup before with no problems? When the 1784-PCM/B card was introduced it only provided drivers up to the Windows 2000 operating system. If you have the up to date drivers for the card (for XP) as well as the current drivers for RSlinx and it still drops offline on you, it may be something with the comms cable or the computer.

http://www.rockwellautomation.com/support/pccards/ #12 is the Driver for XP if you need it.

Maybe this: