Question 1: What can I do, as I cannot connect to the KUS550 Ultrasonic level sensor by RS485.

if the user cannot get any echo from KUS550 Ultrasonic level sensor, there may be something wrong, pls check as below.

1,Check the KUS550 Ultrasonic level sensor is working well, by listen the sound of the probe, if you can find the click sound when you go near the sensor, the means the sensor is working well. Else you can also check the power consumption, the current is around 10mA-20mA, if the current goes too high or too small, maybe there is something wrong with the sensor please contact KACISE for more support.

2,Check the slave ID(slave address) , the KUS550 Ultrasonic level sensor don’t react to the command which with the wrong slave ID(slave address), unless the slave ID is the broadcasting address,0x00. So the user can send the hexadecimal string 00 03 00 28 00 01 05 D3 to the sensor, the sensor will echo the host with the right slave address.

3, Check the UART baud rate. The sensor can only accept the command on condition of the baud rate is match well. the default UART baud rate is 19200bps. The baud rate can be changed by modify the register 0x00 and reboot the sensor. May be the register be changed wrongly, so the sensor have no action the command. This problem can be solved by try to find the right baud rate by modify the host baud rate and to try if can get a right action from the sensor, so there is a better method by send the hexadecimal string 00 03 00 28 00 01 05 D3 to the sensor and during try different baud rate.

The answer will be clear after the three test finished.