SBUS AND XBUS
Futaba’s SBus and JR Propo’s XBus systems are unique, as the servos can be programmed to listen only to the commands of one channel. This allows a single main wire cable to carry the protocols for all the channels, while the programmed servo (and hubs), when plugged into this cable, will listen only to the channel it is programmed to. These systems also allow two-way communication, so it is easy to set up telemetry from sensors installed in the aircraft. Also, with “bus” systems, individual servos can be programmed with different settings in much the same way as programmable servos.
You can match up and program your servos on the bench, but we find that it is easier to have the servos installed in the airplane and attached to their control surface. Working this way, you can quickly see how your programming affects the control surfaces.
Programming is about the same for SBus and XBus servos, but a bonus is that you can also use your computer with a suitable manufacturer’s programmer. Using SBus for example, you can use the PC Link program with the CIU-2 program to adjust the channel so that the servo only listens to that program selected channel, no matter where the servo is connected into the system. The PC Link program and the CIU-2 also enable you to set the direction, speed, endpoint, and other parameters into each SBus servo. This is great for setting up dual elevator servos controlled with a single channel. You can program each servo to have the proper center and endpoints, and the proper servo direction, so they can work as one for a dual elevator setup.