Establishing Accuracy at Power Up
Before starting a system, configure the Ethernet network for a predefined interval, within which the accuracy is established. Accuracy is established at power-up, when the Ethernet module boots and then obtains the time from the NTP server.
Several updates may be required to achieve peak accuracy. Once an accurate time is obtained, the time synchronization service sets the
STATUS in the associated time service register.
Obtaining and Maintaining Accuracy
The time service clock starts at 0 and increments until the Ethernet network time is fully updated from the module.
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Model
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Starting Date
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M340 with Control Expert
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January 1, 1980 00:00:00.00
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Clock characteristics:
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Clock accuracy is not affected by issuing stop/run commands on the PLC
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Clock updates are not affected by issuing stop/run commands on the PLC
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Mode transitions do not affect the accuracy of the Ethernet network
Reinitializing the Time Service Register
After a download or an NTP server swap, the status clock value associated with the time service register in the CPU is reinitialized.
Two polling periods elapse before an accurate time is reestablished.
