Modbus

Wikipedia

• Wikipedia

• Cost free Modbus RTU Device Testing Software
• uTasker MODBUS extension module for Kinetis, Coldfire, SAM7x, LPC2xxx, LPC17xx, Stellaris, STM32

• prices

mbed

• modbus on mbed
• Yuji Hosogaya ModbusTCP_Modified main.c

MBLogic

MBLogic for an open world in automation
MBLogic is a collection of software packages used for communicating with and controlling industrial processes and machinery. 
This collection of packages can be used together or individually, as desired

• Help - Modbus Basics
• MBLogic Software downloads
• MBLogic examples
• http://www.control.com/thread/1295719839
• http://www.linurs.org/linux/Mblogic.html

Python

pymodbus

• Python module pymodbus

modbus-tk

• modbus-tk: Create Modbus app easily with Python

   Modbus TCP support for writing masters and slaves
   Modbus RTU support for writing masters and slaves (requires pyserial)
   Can be customized with hook mechanism (simulate errors, timeouts...)
   ready-to use simulator with RPC interface
   Defines very easily your own memory blocks
   Set/Get values for any place in a memory block
   logging capability through python logging module
   Web-based HMI (requires bottle)

Advantech

• Advantech Modbus Gateway

The Modbus Serial Device Server as an interface between Modbus serial devices and computer hosts running Modbus/TCP on Ethernet networks. Fully compliant with Modbus/TCP, the Modbus Serial Device Server offers a convenient solution to connect existing devices or controllers running Modbus serial protocol (Modbus/ASCII or Modbus/RTU) to an Ethernet network.

Client Simulator

• Free Modbus PLC Simulator Home

PLC with Modbus

• Micro PLC - Small PLC Options From Unitronics at TECHNOLOGIC UK