ABB RELION REX615 - Control Operations; Single Command; Double Command

3.4 IEC 60870-5-104 internal event buffering
The protocol stack instance internally stores change events based on ASDU event
types. The event buffer size per ASDU type is 1000 events. However, this buffer is
shared between all protocol instances activated in the relay. This means that with
e.g. 1 instance active the full 1000 buffer is available, but with e.g. 5 instances only
1000 / 5 = 200 events per instance can be queued at a given time until event buffer
overflows. The protocol stack sends as many event data objects as possible of the
same ASDU event type in one APDU frame.
3.5 Control operations
3.5.1 Single command
Single-command controls are performed towards SPC (controllable single point) IEC
61850 target objects. The command can be given with or without a time stamp
(C_SC_NA_1, C_SC_TA_1). Only direct type operations are allowed.
If time-tagged commands are used, it is important to ensure the master and the
relay times are synchronized. Also, time zone related settings need to be correct,
such as the Time zone (UTC or local) setting and local time offset in general time
settings if local time is used. The maximum accepted delay between the command
time stamp and the relay time can be adjusted by the Command delay setting.
Many target SPC objects, such as acknowledgement or reset objects, are “transient
only” objects. For these objects, only “On” control is relevant. If an “Off” control is
performed to them, most often a positive acknowledgement is returned from the
target function block, but the object’s action, for example, acknowledgement or
reset, is not performed.
3.5.2 Double command
Double-command controls are performed towards DPC (controllable double point)
IEC 61850 target objects, that is, circuit breakers and controllable disconnector
objects. The command can be given with or without a time stamp (C_DC_NA_1,
C_DC_TA_1).
If time-tagged commands are used, it is important to ensure the master and the
relay times are synchronized. Also, time zone related settings need to be correct,
such as the Time zone (UTC or local) setting and local time offset in general time
settings if local time is used. The maximum accepted delay between the command
time stamp and the relay time can be adjusted by the Command delay setting.
Each double-point DPC object has two predefined IEC 60870-5-104 control objects:
one intended for direct operation and the other one for select-execute (select-
before-operate) operation. The difference can be seen in the control object’s signal
name trailing text.
…DPC-ctlVal-Direct
…DPC-ctlVal-SBO
Vendor-specific implementation
2NGA001859 A
20 REX615
IEC 60870-5-104 Communication Protocol Manual