Time Synchronization - Siemens Simatic S7-1500R System Manual

9.7

Time synchronization

Introduction
All S7-1500R/H CPUs have an internal clock. The clock shows:
● The time of day with a resolution of 1 millisecond
● The date and the day of the week
The clock change for daylight saving time is also taken into account.
In redundant mode, the two CPUs of the S7-1500R/H redundant system constantly
synchronize their internal clocks.
You can synchronize the time of the CPUs using the NTP procedure.
Principle of operation
In NTP mode, the device sends time queries at regular intervals (in client mode) to the NTP
server in the subnet (LAN). Based on the replies from the servers, the most reliable and
most accurate time is calculated and the time of day on the S7-1500R/H CPU is
synchronized. The advantage of this mode is that it allows the time to be synchronized
across subnets. You can synchronize the time of day of up to a maximum of four NTP
servers. You address a communications processor or an HMI device, for example, as
sources for time synchronization via the IP addresses.
The update interval defines the interval between the time queries (in seconds). The value
range for the interval is 10 seconds to one day. In NTP mode, it is generally UTC (Universal
Time Coordinated) that is transferred. UTC corresponds to GMT (Greenwich Mean Time).
Conditions
● In the S7-1500R/H redundant system, you need to configure time synchronization in NTP
mode for each CPU individually. If possible, use the same settings for both CPUs.
● The settings for time synchronization with NTP mode are defined at PROFINET interface
X1. PROFINET interface X2 uses the settings from PROFINET interface X1.
● Make sure that the primary CPU maintains a constant connection to the NTP server. The
backup CPU then receives its synchronized time of day from the primary CPU.
Procedure
Proceed as follows to enable time synchronization for a CPU:
1. Configure the interface properties in the "Properties > General > PROFINET interface >
Time synchronization" parameter group. Select the "Enable time synchronization via NTP
server" option.
2. Enter the IP addresses of up to four NTP servers at parameter "Server 1-4".
3. Set the time interval for time queries at the parameter "Update interval".
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA
Commissioning
9.7 Time synchronization
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