×
Siemens Industry Online Support
Siemens AG
Entry type: FAQ, Entry ID: 67225955, Entry date: 02/25/2013
(0)
Rate

2XV9450 SICLOCK: Time synchronisation for industrial plants.

  • Entry
  • Associated product(s)

QUESTION:

Synchronisation concepts for industrial plants.

 

 

ANSWER:

For the reliable time synchronisation of plants the following points are particularly important, if the clocks in the individual controllers and computers are not to drift apart at the first error:

1.       The plant is synchronized by an individual or redundant central plant clock (SICLOCK TC400/TC100).

2.       The input radio synchronisation of the plant is only attached to the central plant clock.  In case of failure of the radio synchronisation, the plant is still uniformly synchronized by the central plant clock running on the internal quartz clock.  The quartz recalibration provides the SICLOCK TC400/TC100 running in quartz mode with an accuracy of from 1 to 2 ppm after interruption of radio reception. The immediate alarm notification from the SICLOCK TC400/TC100 makes possible a fast repair of the radio synchronisation (if the loss is not due to a temporary fall out of the transmitter).  After radio synchronisation returns, the small time deviation that can occur during a failure can be corrected in a subtle manner by switching on the micro mode of the SICLOCK TC400/TC100, without having a single one second interval with unequal thousands of a millisecond occur. A clean time stamp is always possible.

3.       In large plants where multiple central plant clocks might be necessary, these are not attached to radio synchronisation, but are synchronized by the master central plant clock.

4.       The master central plant clock distributes the time to all systems which are to be synchronized.  Here attention is to be paid to a careful selection of the transmitting media used - electrical or optic.  The advantage of time routing over fibre-optic cables is clearly obvious, in particular in areas with strong electrical interference.  SICLOCK makes possible the optical distribution both over LAN and serial asynchronous point-to-point connections