ABB Relion 620 Series - Measurand Registers

The bit address field shows the 1x and 0x Modbus memory addresses on which the
data occur as default. The Modbus register address and bit within the register are
shown under the 3x and 4x register views. The address field may also be empty,
meaning that the object is not located in the Modbus memory at all as default. In any
case the indication objects can be taken into use in the user-definable area.
Only active data objects are shown by the Modbus Communication Management tool.
This means objects that are available in functions which are at this moment activated
in the relay configuration.
Table 11: Setting columns in the Modbus CMT view
Setting column Alternatives Description
Bit address Not adjustable The 0x and 1x bit Modbus memory map
address where the object resides as default.
If the field is empty, the object is not visible in
the Modbus memory map as default. The
object can always be further mapped into the
user-definable area.
Data category
None
1)
Point does not belong to any user-definable
data category.
1...16 Point belongs to data category number N. If
any object belonging to this category
changes its value, bit (N-1) in SSR3 gets
value 1. The SSR3 bit value is automatically
reset when master reads it.
Event enable
Unchecked
1)
No Modbus events generated from this point.
Checked Modbus event is generated when the value
changes. Accurate event time stamp is
inherited from IEC 61850 level.
Rising edge only
Unchecked
1)
Modbus event is generated from both value
transitions; from 0 to 1 and from 1 to 0.
Checked Modbus event is generated only from 0 to 1
transitions.
1) Default setting
3.4.5 Measurand registers
The Modbus measurands are located in the Modbus register area. The measurands are
readable from both 3X and 4X areas from the same register addresses.
The Modbus measurands derive from the IED's internal, original IEC 61850 filtered
measurand values. Modbus register values in this IED are always in integer format.
Since the internal IEC 61850 values are often represented as decimal numbers, the
Modbus stack needs to scale these values to integer format. Thus, there always exists
a scaleFactor and an offset parameter for each Modbus register value. The user can
freely configure these parameters with Communication Management tool in
PCM600.
The formula for calculating the Modbus register value is:
Section 3 1MRS757645 B
Vendor-specific implementation
26 620 series
Communication Protocol Manual