98BDevice configuration
5.6 Configuring the CPU for communication
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
131
①
MAC address
Initially, the CPU has no IP address, only a factory-installed MAC address. PROFINET
communications requires that all devices be assigned a unique IP address.
Use the CPU "Download to
device" function and the
"Extended download to device"
dialog to show all accessible
network devices and ensure that
unique IP addresses have been
assigned to all devices. This
dialog displays all accessible and
available devices with their
assigned MAC or IP addresses.
MAC addresses are all-important
in identifying devices that are
missing the required unique IP
address.
5.6.7
Configuring Network Time Protocol synchronization
The Network Time Protocol (NTP) is widely used to synchronize the clocks of computer
systems to Internet time servers. In NTP mode, the CP sends time-of-day queries at regular
intervals (in the client mode) to the NTP server in the subnet (LAN). Based on the replies
from the server, the most reliable and most accurate time is calculated and the time of day
on the station is synchronized.
The advantage of this mode is that it allows the time to be synchronized across subnets.
The IP addresses of up to four NTP servers need to be configured. The update interval
defines the interval between the time queries (in seconds). The value of the interval ranges
between 10 seconds and one day.