Timesynchronization with ModbusRTU and Modbus TCP communication protocols

Timesynchronization with ModbusRTU and Modbus TCP communication protocols

When Modbus communication protocol is used, time synchronization setup depends on which type of Modbus is used: ModbutRTU (serial) or ModbusTCP(NTP).

ModbusRTU (serial)

Enabling ModbusRTU

Modbus RTU can be enabled with Protocol parameter at Communication > Connections menu at Serial section. Set the Slave address at Communication > Protocols > ModbusRTU.

Time synchronization

Set Time sync. source parameter to Serial at General menu.

Time zone

In general when serial time synchronization is used with Modbus RTU it is expected that the time sent to relay is UTC time. In this case the time zone should be set at Commands > Set time zone. This setting will correct the time displayed on AQ-200 unit clock and timestamps in event history. The events reported to SCADA will use UTC time.

If local time is sent to relay instead of UTC time, no time zone setting should be set. If time zone has been set to the relay this can be reversed by setting Etc/UTC as the time zone.

ModbusTCP (NTP)

Enabling ModbusTCP (NTP)

ModbusTCP can be enabled at Communication > Protocols > ModbusTCP. Set the IP address used by ModbusTCP at Communication > Connections.

Time synchronization

Set Time sync. source parameter to NTP at General menu. Set the NTP server IP address at Communication > Protocols > NTP. AQ-21x frame units need also client IP address set that is unique from the IP address set at Communication > Connections.

Time zone

In general when NTP time synchronization is used with Modbus TCP it is expected that the time sent to relay is UTC time. In this case the time zone should be set at Commands > Set time zone. This setting will correct the time displayed on AQ-200 unit clock and timestamps in event history. The events reported to SCADA will use UTC time.

If instead of UTC time local time is sent to relay instead, no time zone setting should be set. If time zone has been set to the relay this can be reversed by setting Etc/UTC as the time zone.
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