ESC Problem

Hello dear community, I have the following problem, I bought the Pixhawk 4 and my 6 ESCs don’t get a signal to start the motors. I have a Bec for each ESC with which only the signal cable leads to the I / O PWM Out distributor. Do not need a PMB as each ESC has its own battery. What settings can you make to get the ESC signal?
T-motor 43 kv
Flier Esc 400 a
Receiver FS IA 6 B