address "0". Thus, all IEDs in the same serial network can be synchronized at the same
time.
Method 1: Synchronization in one step
The registers 49201...49208 (49211...49218) should be written in one multiple
registers preset request (function 16) by a Modbus TCP/IP client or by a serial
interface master. The IED's Modbus address or the Modbus broadcast address can be
used with the serial interface. If the clock is written in one step, the write value of the
register 49201 (49211) is not checked by the IED.
Method 2: Synchronization in three steps
1. The client reserves the time synchronization by writing value "1" to the register
49201 (49211). If necessary, check that the reservation value is zero at the
beginning. If the time synchronization writing is already reserved by another
client, the IED returns the exception response 03.
2. The client writes the time structure to the IED. This can be done in one transaction
or alternatively each register can be written separately.
3. The client sets the clock by writing "2" into the register 49201 (49211). When the
value "2" is written, the timesync registers are latched onto the IED's internal
clock and the reservation in 49201 (49211) is released.
The Modbus broadcast address cannot be used with the
synchronization method 2.
There is an internal timeout for the clock setting. The time synchronization reservation
is released if the clock is not set within two minutes. The client can abort the time
synchronization at any time by writing "0" into the register 49201 (49211). In that case
the real-time clock is not set at all.
Other Modbus clients can read the currently running real-time clock even if the time
writing is reserved by another client.
3.4.13 Device information
The device information of the IED can be read from the Modbus registers
49001...49083.
If the information data are in practice shorter, the trailing registers in
the response are filled with the value "0".
The Modbus device information is based on the internal IEC 61850 device
information model of the IED. All internal descriptions are coded as ASCII strings.
The Modbus device information ASCII string includes the information from the IED.
1MRS757645 B Section 3
Vendor-specific implementation
620 series 61
Communication Protocol Manual
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