@EasyIoT said: uint8_t length = min(strlen(value), MAX_PAYLOAD); Thanks, update pushed.

@EasyIoT Can you share your implementation for MySensorsDriver?

Also in RelayActuator.ino void setRelayStatus(message_s message) { if (message.header.messageType=M_SET_VARIABLE && message.header.type==V_LIGHT) { is better: void setRelayStatus(message_s message) { if ((message.header.messageType==M_SET_VARIABLE || message.header.messageType==M_ACK_VARIABLE ) && message.header.type==V_LIGHT) { Be careful message.header.messageType=M_SET_VARIABLE and message.header.messageType==M_SET_VARIABLE is not the same.