Toshiba GR-200 Series Instruction Manual page 591

Synchronization using Modbus
(iv)
Time synchronization is possible when IEDs (Modbus slave) are connected with the substation
computer (Modbus master) over the Modbus communication†. It is achieved by transferring
time data over the Modbus commination. The time synchronization is carried out by the write
multi registers function—Function code 0x10 (16).
Chapter Communication protocol: Modbus communication
†Note: See
details.
Example of Modbus TCP time synchronization
Time synchronization is achieved by the Modbus TCP. Figure 5.8-9 shows IEDs are connected
with the time-servers over the Ethernet LAN.
Substation computer (Modbus Master)
IED (Modbus slave)
Device1
(192.168.11)
Figure 5.8-9 Time servers connected by Modbus TCP
Example of Modbus serial (Modbus RTU)
The Modbus RTU also does that. Figure 5.8-10 shows IEDs are connected with the time-servers
via serial cables.
Substation computer (Modbus Master)
Time server
IED (Modbus slave)
Device1
(Address=0)
Figure 5.8-10 Time servers connected by Modbus serial (Modbus RTU)
Time data for the Modbus
The master sends time data for the slaves, and the content of the time data is written by the
mater in accordance with the data format, as shown in Table 5.8-4. For example, we can get
the Modbus time (0x 16 2E 03 04 01 02 00 13), when it is "3:04'5.678 a.m., January 2, 2019".
Time server
TCP master query
Device2 Device3
(192.168.12) (192.168.13)
RTU master query
Write Multi Registers (FC:0x10)
Device2
(Address=1) (Address=2)
- 572 -
Write Multi Registers (FC:0x10)
Ethernet LAN Network
Device3
6F2T0200 (0.15)
(→p. 795), for more
Device n
(192.168.xx)
RS485 serial cables
Device n
(Address=n-1)
GRE200 (1,2)