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Section 3
Vendor-specific implementation
3.2.3
3.3
3.3.1
3.3.2
16
Exception codes
Table 8:
Supported exception codes
Function
Name
code
01
Illegal function
02
Illegal data address
03
Illegal data value
Application data
Modbus data objects
The Modbus protocol in 615/620 series IEDs is built on top of the internal IEC 61850 data
model. Thus, the Modbus application data objects, proprietary events and MCD bits are
derived from IEC 61850 data objects and data set reporting. The 615/620 series IEDs have
a predefined IEC 61850 data set configuration. In other words, it is predefined which
internal data object changes the 615/620 series IEDs detect.
The available Modbus indications in the 615/620 series IEDs are generally selected from
the IEC 61850 indications residing in data sets. Objects that do not reside in any data set
are updated to the Modbus database slower. This concerns, for example, some measurand
register values. Fast changes in these object values may not be detected or propagated to
the Modbus database. However, the latest value of these objects is always found in the
Modbus database. The DS column in the Modbus point list manual shows if the object
resides in some data set as a default.
For a list of the available data objects, see the point list manual.
Modbus data implementation
The numeric register locations used in this section are for example
purposes only. The genuine Modbus register locations are located in the
IED's memory map.
The IED is internally modelled according to the IEC 61850 standard. The Modbus
protocol is implemented on top of this model. However, all features of the IEC61850 data
model are not available through the Modbus interface.
The Modbus protocol standard defines one bit digital data and 16 bit register data as the
application data alternatives but it does not define exactly how the digital data and the
register data should be used by the application. Instead, the choice of the usage is left to
the IEDs implementation.
1MAC052634-MB D
Description
The slave does not support the requested
function.
The slave does not support the data address
or the number of items in the query is
incorrect.
A value contained in the query data field is
out of range.
615/620 series ANSI
Communication Protocol Manual
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