The IEC 60870-5-103 standard defines indications to be of ON/OFF type. The value coding for indications is always DPI, where only values 1 and 2 (binary 01 and 10) are used. Value 1 means OFF and value 2 means ON. Indications are assigned to IEC 60870-5-103 Class 1 data transactions.
Indications relate to general purpose signals or protection signals (start and trip). The standard defines two ASDU object types for indications: ASDU 1 and ASDU 2. ASDU 1 type is intended for general purpose objects and ASDU 2 type for protection objects. These ASDU types are shown as TypeID 1 and TypeID 2 in the Communication Management tool of PCM600.
The IEC 60870-5-103 standard was originally defined for protective equipment only. Therefore the standard does not include circuit breaker control and object definitions. For circuit breaker and disconnector position information the IEC 60870-5-103 DPI value is extended to include the values 0 and 3 (binary 00 and 11) also. These values represent the four-pole object’s intermediate and faulty positions.