You are not going to get very far with some of these suggestions. By specification 232 has to go 60 ft using shielded, twisted pair. CAT5 is technically a different story but it probably is not going to be the issue. Proper termination is typically avoided when UTP is used. Both TX and RX should have their pairs wired to ground. In other words if OR and GR solid are RX and TX OR/WH and GR/WH should be tied to ground. Rarely is this done. In reality, you can often send RS-232 much further, especially at lower baud rates like 9600. But many issues can effect commands as it is a digital signal, that is made up of square waves. If the wire is too close to a high voltage cable, security cable or some other wire causing induction problems could result. If you just want an out, send an OFF command via IR and figure out the timing for the multiple commands.

Very few devices require by protocol multiple serial commands to turn a projector off. As a practical matter this is often done. Proper coding technique would be to write the macro so that off commands are sent till off_FB is received. This introduces a whole other set of issues regarding polling speed and robustness of serial protocols.

To your problem: You can follow the advice to send the commands multiple times. How far should you space them? And if you are including lift up commands as part of the macro rather than on the off_fb argument you will play with fire no matter what you do. If you have a lift in the system the best procedure is to tie the Lift_UP command to projector feedback that it is cooling down. Failing reliability you might as well use IR as you are in essence doing the same thing with serial by not using the feedback in your code.

OK, solving the problem: Only way to do this is to look at the actual commands being sent and received. This might require putting your computer at the projector and seeing if the command arrives without any issues in the square wave. Use a terminal emulation program for this. 2. See what responses to your command the projector gives. If it's an error code, as I suspect, figure out what it means and fix the macro. Since you probably cannot fix the macro ask C4 to do it. Since they probably will not is there an alternative way to issue the code you can send? Can you write your own command for off? Generally speaking, many who write modules like to include a polling command with it and timing of this can sometimes cause problems. Turn off polling if this is an option but often it's not. Hence we return to using a different "OFF" signal

Alan