Wingpath Software Development has released ModSlaveSim, a programmable Modbus slave simulator. It will be of particular interest if you are a system integrator or software developer. A system often needs to be developed and tested before a slave device is available, or when a slave device cannot produce realistic data because it is not yet fully installed in a live system.
You can connect your master software to ModSlaveSim instead of the real slave device, and ModSlaveSim will provide you with a changing and responsive environment with which to test and configure your master.ModSlaveSim enables you to simulate not only the internal logic of a Modbus slave device, but also the environment of the device: the values it measures (temperatures, flow rates, etc.) and the equipment it controls (valves, motors, etc.). The simulation is specified using a simple control language.
Each register may have a statement in this control language associated with it. This statement defines the register value in terms of previous register values and the current time. The computation of register values is done cyclically, with a configurable cycle-time, in a manner similar to most real slave devices.ModSlaveSim supports both serial (RTU and ASCII) and network (TCP) interfaces. It has flexible address mapping, allowing separate or overlaid address spaces for coils, discrete inputs, input registers and holding registers, with arbitrary bases.
All known extensions of the Modbus protocol for transferring floating-point numbers and 32-bit integers are also supported.Since it is written in Java, ModSlaveSim can be used on any platform that supports Java (JRE 1.3.1 or later), including Microsoft Windows, Linux, Solaris and AIX.A free download of the full version of the program is available for evaluation from Wingpath's web site at http://www.wingpath.co.uk/modslavesim.php .
