Physical connections are described below. It is the same for SatPC32 or HRD or any other satellite (or camera, laser, etc.) control program that supports EasyComm I or EasyComm II protocols
(a) Leave the Arduino connected to the PC with the same USB cable that you used to program it.
(b) Use a long 4 wire long cable to go from the Arduino to the Servos as illustrated below.
Sample Wiring Diagram:
Arduino 6 ------------------(YELLOW)--------------------- Control Signal to Servo 1
Arduino 9 -------------------(BLUE)---------------------- Control Signal to Servo 2
Arduino GND ---|
X -----------(BLACK)~~~~~~~~~~~~~~~------- Common GND to Servos
PSU GND -------|
PSU +6V ---------------------(RED)----------------------- Common +V to Servos
(c) PSU is an separate power supply (5 to 6 volts 3 Amps ) that supplies the current to the servos.
(d) The PSU GND and the Arduino GND are connected together like a Y connection at the junction marked X.
(e) At the Servo end the +V and GND from the 4 wire cable is tied commonly to both servos, while the signals are fed to one servo each.
(f) Colors are suggestions only, your cable may use different colors...
(g) For long lengths it will be best to use a shielded cable and ferrite clip-ons at each end, just connect the shield to PSU GND.
I found this arrangement works best.