Am working on a project at the moment that has raised a couple of interesting questions. The project involves intergrating a control 4 home theatre system with an existing c-bus network. The control 4 system supports 2 way comms with c-bus via rs 232. 1. Connecting to the rs232 port of the PCI we have comms and things work, although we did have to turn off the c-bus clock in the PCI and move it to another device. BUT, if we connect to the rs 232 port of the PAC we cannot get it to work, we have powered the PAC with a seperate 24 volt supply. Can anyone tell me why this might be so? 2. With the application log of the control 4 system running we see the message " [I]invalid 17[/I] " constantly scrolling, approx 2 per second. All other group addresses report normally. The invalid 17 message does not appear in the c-bus application log. Everything still works ok I am just worried that the constant traffic may upset something as we build more operations into the setup. Thanks, Peter.