Module: Modbus® (Modbus)
Module: Modbus
®
(Modbus)
Modbus
Modbus
®
Protocol Configuration
The time-controlled Modbus
®
protocol is based on the Master-Slave working principle. This means that the
substation control and protection system sends an enquiry or instruction to a certain device (slave address)
which will then be answered or carried out accordingly. If the enquiry/instruction cannot be answered/carried out
(e.g. because of an invalid slave address), a failure message is returned to the master.
The Master (substation control and protection system) can query information from the device, such as:
•
Type of unit version
•
Measuring values/Statistical measured values
•
Switch operating position (in preparation)
•
State of device
•
Time and date
•
State of the device’s digital inputs
•
Protection-/State alarms
The Master (control system) can give commands/instructions to the device, such as:
•
Control of switchgear (where applicable, i.e. each acc. to the applied device version)
•
Change-over of parameter set
•
Reset and acknowledgement of alarms/signals
•
Adjustment of date and time
•
Control of alarm relays
For detailed information on data point lists and error handling, please refer to the Modbus
®
documentation.
To allow configuration of the devices for Modbus
®
connection, some default values of the control system must be
available.
EN MRU4 10/09
Page 161
