The introduction of microprocessors in the beginning of the 1980s changed the environment of the developers of devices for process control for the first time. Microcontrollers like the 8031 family at these times already had serial interfaces and soon the engineers (myself included) started to use them for debugging and production purposes. Later the serial interface was introduced as digital communication to offer new functionality to the users of the devices.

It was logical that it would be of advantage to standardize the usage of the serial interfaces. The idea of fieldbus was born by the middle of the 1980s and we all know how this development of a fieldbus standard ended. It is interesting that the HART Protocol and MODBUS - two of the most popular field communication protocols - are 'only' industry standards.

At the begin of the 1990s the engineering consultancy Borst Automation started into business. Meanwhile Windows was replacing DOS in PC programming. Unfortunately at this time programming under Windows was rather complex compared with the former DOS. The developers of embedded systems for process control and measurement had no time to master Windows programming quickly enough and the managers of their companies made statements like: "Windows is not our core competence!". This was a chance for Borst Automation to start to develop Windows programs for the configuration of field devices with HART communication, PROFIBUS, MODBUS and others.

By end of the 1990s Windows was no longer a mystery because tools like Delphi, Visual Basic and others where available. Now there was a need for drivers handling the communications. This was difficult regarding a HART master because this entity needs a real time state machine working in the range of a few milliseconds. By 1998 Borst Automation successfully introduced an Active X for the HART protocol. The software product was named ActiveHART and with a later release HartX 3.0.  This OCX was based on the OLE interface of Windows and acts similar to an OPC server. An Active X is very nice and easy to use in Visual Basic or Delphi applications. Connecting an Active X to pure C is nearly impossible. Therefore we developed a new driver recently as a 'simple' Windows DLL for the HART protocol. If you like you may download a free trial right away on the top of this page.

Another method serving the need to improve the quality of a software product is the use of a PC-Simulation. This allows the developer to implement most of the device software within e.g. a Visual Studio environment. Visual Studio is one of the most efficient tools for software development. About 90 % of the device software can be developed using the PC simulation. Another aspect of the issue is that software development can be started without having any hardware available.

VARIABLE range_limit_upper
{
  CLASS CORRECTION;
  LABEL "UPPER RANGE LIMIT";
  TYPE FLOAT
  {
    DISPLAY_FORMAT "3.2f";
  }
  CONSTANT_UNIT "Bar";
  HANDLING READ;
}

In 1989 there was the first presentation of a complete fieldbus system with measuring instruments and actuators, a SCADA system and a hand held terminal conducted by a couple of key companies in process automation. I was the project manager for Endress+Hauser at this time. Because of the great acknowledgment by the potential users the International Fieldbus Group (IFG) started to develop specifications and requirements to support the international work on fieldbus standards in 1990. Within this group I was one of the two key developers of device description language (DDL). At the end of 1990 the first specification was released within the IFG. Later Rosemount Inc. extended it by the command mapping functionality and included it into the HART specification.

A couple of years later DDL was also introduced by PROFIBUS and Fieldbus Foundation. Meanwhile it is known as EDDL and became an international standard. The DD in HART, PROFIBUS and FF are very similar but - what else did you expect? - slightly different. This means that for each communication protocol and each device variant another DD is required. How can the costs for this effort be reduced?  The answer is: Single Source Concepts. The basic idea is to put all the information about the parameters of a device into a database. This database is used by generator programs to produce different DDs and - in a lot of cases - C source code for the framework of the embedded system. Borst Automation is offering consulting services for the development of such single source databases and generator programs. In the free software package for HART Revision 5 an example is given how Microsoft Access can be used as a source code generator.