Rob, first I want to say that your suggestion on my previous thread fixed the problem of no air on the 3400s by itself. However, I plugged everything into the VP-X Pro, and under line 36 VP-X configuration, it says that the VP-X is off line. I have now powered up almost every device through the VP-X Pro, and they work fine. I have the 3 shielded data wire cable plugged into the 9 pin serial port on the 3400s. Since I don’t know which serial port is #1, #2, #3, and #4, I tried under Admin settings to set #1 port to the VP-X and it won’t give me the option to set it to the VP-X Pro. I tried the same with # 2 port and it was the same. With my computer connected to the VP-X and using the Configurator, it says the EFIS data is missing. I checked the continuity end to end of each wire in the data cable. They checked good. I checked to see if the wires were grounding to each other. That checked good. I checked to see if the wires were making ground. That checked good. So I really think the data cable is good. The first wire is connected to pin #6 on the 3400s and the other end to VP-X J 1 pin 20. The second wire is connected to #2 pin and the other end to J1 pin 21. The last wire is connected to pin #1 and other end to J 1 pin 22. (8 0 8 – 12 M16). So what do I have to do to get the VP-X data cable ON LINE? Thanks