The standardization process in SCADA communication protocols has been primarily driven by the special requirements of electric power SCADA. This process began with the International Electrotechnical Commission in the 1980s. ITE Technical Committee 57 to look at the standardization of communication between substation and control centers. The committee produced a standard, IEC 60870, in many parts, to address requirements and definitions for SCADA communications for electric power control. The first part of standard was published in 1988 and work on the series is still continuing. The various parts cover:
• Basic concepts
• Environmental characteristics
• General principles of data integrity
• A three layer stack architecture
• Data link services
• Application functions
• Data formats
• Application objects
The IEC 60870-5-5 series of standards present a general ‘recipe book’ for defining communication protocols. IEC 60870-5-101 is companion standard that presents a work example profile for an electric power SCADA protocols based on the earlier parts of the series.
While the IEC was progressing with the development of the 60870 series, vendors, particularly those in North America, where well aware of the power industry’s requirement for standardized SCADA communication. Many utilities were aware of the IC’s work and were requesting ‘IEC Compliant” SCADA Protocols.