What is this?

• Proof of concept program written in plain C that:
  • Speaks modbus protocol using libmodbus
  • Reads information like spindle speed and status from a spindle via an inverter (hitachi wj200) over modbus RTU
  • Updates the spindle speed in a loop
  • Relays these information to a Kepware Server via Modbus TCP/IP (or any connection configured)
• Tested on OSX Sierra 10.12.6 and Windows 10
• Blog post that explains it, is being written.

Simplified Demo

There is a simplier version that lives inside the simplified branch if you do not want to have libconfig as a dependency. But the configs and addresses for connections / registers are all hard coded.

Re-defining Connections

• libconfig is used to parse the config file; I use this file to define
  • the modbus connections &
  • the addresses of the registers / coils in the modbus setup
• Can be easily changed to work with whatever device and data addresses, either via Modbus RTU or Modbus TCP/IP.

Sample config.cfg

You may find a sample of a config file here: https://github.com/aranair/modbus_adapter/blob/master/config.cfg

Virtual Serial Ports via Pseudo Terminal

If you want to test RTU mode using pseudo terminal on localhost:

• brew install socat
• socat -d -d pty,raw,echo=0 pty,raw,echo=0 to get two pseudo terminals assigned.
• cat < /dev/ttys035> on a new terminal 2
• echo "Test" > /dev/ttys037 on another new terminal 3 to see the results on terminal 2

Building it from source

OSX

gcc slave_server.c -o slave_server `pkg-config --libs --cflags libmodbus`
gcc master_client.c -o master_client `pkg-config --libs --cflags libmodbus`

Windows

• Visual Studio 2017
• Open the solution file in the win32 folder

Dependencies

• libconfig
• libmodbus

License

MIT