YOKOGAWA Vnet/IP, Technical Information

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4. Appendix
4-6
TI 30A10A05-01E
n
Time synchronization between Vnet/IP domains
If there are multiple domains, the time is synchronized between domains that belong to the same
time group.
A time group enables selection of a network time master from the domain master station
within domains that belong to the same time group. A network time master is also selected
automatically. It is not necessary for you to identify the network time master.
Vnet/IP defines time groups in the domain properties of the CENTUM engineering function on a
domain-by-domain basis. The time group is specified by using numbers 0 to 7. The time is not
synchronized for domains whose time group is 0.
The time synchronization accuracy of the network time between domains is expressed as
follows:
±5 msec (When one bus is abnormal, the accuracy may become worse than ±5 msec)
The time synchronization accuracy becomes worse in proportion to the transmission delay time
variations between domains.
L2SW L3SW
Domain 2
network time
system time
HIS
FCS, SCS FCS, SCS
HIS
(domain master)
network time
system time
network time
system time
network time
system time
network time
system time
network time
system time
L2SW
Domain 1
network time
system time
HIS
HIS
(domain master,
network time master)
F040302E.ai
HIS
Time
synchronization
services
Direction of time synchronization
Note: Bus 2 is omitted in the figure
Figure Time Synchronization Between Domains in the Same Time Group
Aug.19,2011-00