Arduino On without VCC

Using Arduino Microcontrollers
1

Good night friends, i'm using serial communication between two Arduino , I'm power the same with same source , but use a key to turn on the slave ON only when I want, but even with the off key, the slave is energized due to contact of gnd always be active , as Can solve this without the use of a second source ????

2

bieldp3:
i'm using serial communication between two Arduino...

Add a resistor between the Tx to Rx connections (both), around 5k or so.

TX ---- 10k ---- RX
RX ---- 10k ---- TX
3

Thanks!!!