Different Modbus indications originating from the same IEC 61850
data attribute have an identical UID. It is therefore recommended to
use the Modbus address as the identification instead of the UID.
Data value identification bits 5..0
Coding of the event data value is one bit, two bits or 32 bits. The coding depends on
the IEC 61850 common data class which is the origin of the Modbus data in question.
Table 28: Modbus event value alternatives
Object derived from
IEC 61850 Class
Meaning One Bit Data
Value
Two Bit Data
Value
32 bit Data
Value
SPS Single Point Status X
SPC Single Point Status of a controllable
object
X
DPS Dual Point Status X
DPC Dual Point Status of a controllable
object
X
ACT Trip status X
ACD Start/Pick-up status X
INS/INC Integer status X
Table 29: Interpretation of the one-bit data value
Register 49261 binary coded value
Meaning
xxxx.xxxx.xxxx.xxx0 Object in OFF position
xxxx.xxxx.xxxx.xxx1 Object in ON position
Table 30: Interpretation of the two-bit data value
Register 49261 binary coded value
Meaning
xxxx.xxxx.xxxx.xx00 Object in intermediate position (changing)
xxxx.xxxx.xxxx.xx01 Object in ON (close) position
xxxx.xxxx.xxxx.xx10 Object in OFF (open) position
xxxx.xxxx.xxxx.xx11 Object in faulty position
In case of a DPS/DPC two-bit event value (Data value identification
= 2), the data object ID registers 49259 and 49260 always refer to the
Modbus address or UID of the CLOSE momentary value bit.
Table 31: Interpretation of the integer status data value
Register address
Meaning
49261 Higher 16 bit part of the 32 bit integer value
49262 Lower 16 bit part of the 32 bit integer value
1MRS757645 B Section 3
Vendor-specific implementation
620 series 53
Communication Protocol Manual
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