@user2684 Yes, i have changed the Adafruit library. NodeManager code is ok: it generates an "ERROR" message when "(_tsl->begin())" fails. But, in the current Adafruit library begin() never fails. Thanks for the fast response.

Hi,
i'm using the sensor TLS2561 and NodeManager 1.7. I installed the libraray "TSL2561-Arduino-Library" as it is described in the README.md.
The function TSL2561::begin returns always true notwithstanding if the address mode (TSL2561_ADDR_HIGH|FLOAT|LOW) not matches the hardware setting of the address line (high|floating|low).

  Wire.requestFrom(_addr, 1);
#if ARDUINO >= 100
  int x = Wire.read();
#else
  int x = Wire.receive();
#endif
  //Serial.print("0x"); Serial.println(x, HEX);
  if (x & 0x0A ) {
    //Serial.println("Found TSL2561");
  } else {
    return false;
  }
  _initialized = true;

So, if the address matches the TLS2561 anwers with 0x0A. If the address does not match the I2C bus will read as 0xFF. In this case the statement "if (x & 0x0a)" will also be true.
I changed the statement to "if (x == 0x0A)" and the function works correctly.
@user2864 Maxbe you could intiate a change in the library. I don't know how to do that in the github environment.
Greatings from germany, mabe with a special german english:relieved: