Basics view of T101

T101

T101 or IEC 60870-5-101 (IEC101) is an international standard prepared by TC57 for power system monitoring, control & associated communications. This is compatible with IEC 60870-5-1 to IEC 60870-5-5 standards and uses standard asynchronous serial tele-control channel interface between DTE and DCE. The standard is suitable for multiple configurations like point-to-point, star, mutidropped etc.

T101 features

60870-5-101 or T101 have many features such as the following:

• Supports unbalanced (master initiated message) & balanced (master/slave initiated message) modes of data transfer. ­Link address and ASDU addresses are provided for classifying the end station and different sectors under the same. ­Data is classified into different information objects and each information object is provided with a specific address. ­Facility to classify the data into high priority (class-1) and low priority (class-2) and transfer the same using separate mechanisms.
• Possibility of classifying the data into different groups (1-16) to get the data according to the group by issuing specific group interrogation commands from the master & obtaining data under all the groups by issuing a general interrogation.
• Cyclic & Spontaneous data updating schemes are provided. ­Facility for time synchronization Schemes for transfer of files SCADA Communication & Protocols Page 2 of 8 SCADA Communication & Protocols Page 3 of 8 3.3. Types supported by T101 Distributed Control System components are usually included in SCADA. IEDs, RTUs or PLCs are also commonly used; they are capable of autonomously executing simple logic processes without a master computer controlling it. A functional block programming language, IEC 61131-3, is frequently used to create programs which run on these RTUs and PLCs. This allows SCADA system engineers to perform both the design and implementation of a program to be executed on an RTU or PLC. From 1998, major PLC manufacturers have offered integrated HMI/SCADA systems, many use open and non-proprietary communications protocols. Many third-party HMI/SCADA packages, offering built-in compatibility with most major PLCs, have also entered the market, allowing mechanical engineers, electrical engineers and technicians to configure HMIs themselves.

 Remote Terminal Unit

• Single indication without / with 24 / with 56 bit timestamps.
• Double indication without / with 24 / with 56 bit timestamps.
• Step position information without / with 24 / with 56 bit timestamps.
• Measured value – normalized, scaled, short floating point without / with timestamps.
• Bitstring of 32 bit without / with timestamps.
• Integrated totals (counters) without / with timestamps.
• Packed events (start & tripping ) of protection equipments
• Single commands
• Double commands
• Regulating step command
• Set point commands of various data formats
• Bitstring commands
• Interrogation commands
• Clock synchronization & delay acquisition commands
• Test & reset commands.