Downloading Modbus4J-src from sourceforge, you get a file, called Test.java helping you to set up a Modbus/Tcp master ..
Is something similar available for Modbus RTU?
The device I'm having supports only the following instructions:
03 (0x03) Read Holding Registers
04 (0x04) Read Input Registers
06 (0x06) Write Single Register
16 (0x10) Write Multiple Registers
17 (0x11) Report Slave ID
In the Modbus specification, register numbers are documented as "one based", but transmitted as "zero based" -- How are the frames created in Modbus4J for the RS485 bus? 1000 is 1000 (0x03E8) or 1001?