Modbus: NPK-Sensor does not respond at all

Projects Networking, Protocols, and Devices
142

Thank you for the reply @markd833!

Unfortunately, after trying the codes that you have provided, I am still being encountered with the same values.

This one:

If you wish to carry on using canned modbus messages, then this post should provide a slightly better way of communicating with the NPK sensor.

Gives me:

Nitrogen: 01 03 02 00 00 B8 44 
0 mg/kg

Phosphorous: 01 03 02 00 00 B8 44 
0 mg/kg

Potassium: 01 03 02 00 00 B8 44 
0 mg/kg

Whereas this:

For a better way of communicating with the NPK sensor, you should use a Modbus library. Take a look at post #116 here , which uses a Modbus library.

Gives me:

   Nitrogen: 0 mg/kg
Phosphorous: 0 mg/kg
  Potassium: 0 mg/kg

I am still using a 4800 baud rate since 9600 gives me "Response Timed Out".

Also, the 9v battery that I am using is indeed a PP3. However, it's only for the NPK sensor's power source. For now, the Arduino is still connected to the laptop and will only be connected to the batteries after resolving the current issue.