serial monitor not showing value

Hi, i’m trying to communicate 2 NodeMCUs using serial communication.

The first NodeMCU acts as master that connected with an OLED LCD 128x64 and a RTC ds3231
and the other NodeMCU as the slave with MPU6050 accelerometer sensor.

I am trying to send sensor value from slave to master using SoftwareSerial. It works at first but after i plug it out from the power source and plug it in again it stops showing values on serial monitor.

communication :

vin->vin
gnd->gnd
d2->d2
d3->d3

I2C.ino (2.3 KB)

MPU6050-KalmanFilter.ino (6.77 KB)

SERIAL_UNO.ino (6.1 KB)

Disconnect the RX/TX lines between the two devices.
Power cycle both devices.
Reconnect RX/TX lines.
Does it work?

It is usually a bad idea to disconnect power from one of the devices while data lines are still connected. The device that does not have power can be powered from the other device through the data lines and this can damage the data pins on the device that is still powered.

Not said that that happened but it might be the case; to test, write a minimal sketch for both devices to test communication.