gengo-modbus

Modbus TCP client and server library written in Gengo.

A real-world use of Gengo's module system, module-qualified types, bitwise operators, structural interfaces, and the cap:net TCP capability.

Requirements

• Gengo v0.5.0-pre6 or later
• cap:net capability (--cap net for client, --cap net=listen --net-listen-allow <addr> for server)

Quick start

# terminal 1 — start the server
gengo --cap net=listen --net-listen-allow 127.0.0.1:5020 --modules ./modbus server_demo.gengo

# terminal 2 — run the client demo
gengo --cap net --modules ./modbus demo.gengo

Module layout

modbus/
  constants.gengo   Function codes and exception codes
  frame.gengo       MBAP frame build + parse
  client.gengo      Client struct, Connection interface, read/write functions
  server.gengo      Server with data stores, range callbacks, listen
  codec.gengo       IEEE 754 float / integer register codec
demo.gengo          Client demo (temperature controller)
server_demo.gengo   Server demo (temperature controller)

Documentation

• Client API
• Server API
• Codec
• Design notes