Īs the suppliers made the transition to COTS components, they also discovered that the hardware market was shrinking fast. Fieldbus technics have been used to integrate machine, drives, quality and condition monitoring applications to one DCS with Valmet DNA system. Some suppliers built new systems from the ground up to maximize functionality with fieldbus, such as Rockwell PlantPAx System, Honeywell with Experion & Plantscape SCADA systems, ABB with System 800xA, Emerson Process Management with the Emerson Process ManagementDeltaV control system, Siemens with the SPPA-T3000 or Simatic PCS 7, Forbes Marshall with the Microcon+ control system and Azbil Corporation with the Harmonas-DEO system.

Towards the end of the decade, the technology began to develop significant momentum, with the market consolidated around Ethernet I/P, Foundation Fieldbus and Profibus PA for process automation applications. The first fieldbus installations occurred in the 1990s. The 1990s were also known for the 'Fieldbus Wars', where rival organizations competed to define what would become the IEC fieldbus standard for digital communication with field instrumentation instead of 4–20 milliamp analog communications. Internet technology also began to make its mark in automation and the world, with most DCS HMI supporting Internet connectivity. The introduction of Microsoft at the desktop and server layers resulted in the development of technologies such as OLE for process control (OPC), which is now a de facto industry connectivity standard. Availability of a fully functional graphical user interface was a way away. A workstation provided visibility into the process using text and crude character graphics. A more conservative approach was setpoint control, where process computers supervised clusters of analog process controllers. Sophisticated (for the time) continuous as well as batch control was implemented in this way. All of these were DDC applications implemented within minicomputers (DECPDP-11, Varian Data Machines, MODCOMP etc.) and connected to proprietary Input/Output hardware. In the early 1970s Taylor Instrument Company, (now part of ABB) developed the 1010 system, Foxboro the FOX1 system, Fisher Controls the DC 2 system and Bailey Controls the 1055 systems.

Computers had already been applied to process automation for some time in the form of both direct digital control (DDC) and setpoint control. The DCS largely came about due to the increased availability of microcomputers and the proliferation of microprocessors in the world of process control.

Scada and distributed control system