Dual-channel RS485 Expansion Hat for Raspberry Pi 5/4B to be used with SEN0601
Tooba.Tanveer 2026-04-03 02:32:25 31 Views1 Replies Hello I am using a raspberry pi 4b as a microcontroller and have a Dual-channel RS485 Expansion Hat for Raspberry Pi 5/4B attached to it through one on one pin connection so I can get EC data from a SEN0601 sensor. I have never used any of these products before and I am using the sample code provided for the hat with the SEN0601 address and changing what is told to change in instructions but I a not getting any output at all. It throws an error on reaching cst.Read_Holding_registers whioch says Response length is invalid 0. I need urgent help on this please!!
"Invalid response length 0" means the sensor isn’t responding.
Quick checks for try:
1.Check RS485 wiring (A→A, B→B) and 5V power.
2.Ensure DE/RE pin of your RS485 hat is controlled properly.
3.Use default Modbus: 9600 baud, slave ID 1.
4.Verify Raspberry Pi UART is set correctly (disable serial console).
Yx 
