7.4.3 Highly precise time stamp with 1 ms precision
Rules
The following configuration is permitted for the high-precision time stamping with 1 ms
accuracy:
● Automation system with high-precision time synchronization
A time-of-day master, e.g. SICLOCK TM, must be available in the automation system for
this.
● ET 200PA SMART with IM 650
● No RS 485 repeaters between the DP master and the ET 200PA SMART on which input
signals are to be time stamped
● Only digital input modules are permitted to be used in the ET 200PA SMART.
● Only a maximum of 8 modules may be plugged in the ET 200PA SMART.
● Only signals of the digital input module 6ES7321-7EH00-0AB0 may be time stamped.
– The assigned input delay of all digital inputs for time stamping must be identical and
equal to the minimum value (100 μs).
– Hardware interrupts of all modules must be deactivated.
● Input signals that are to receive a time stamp must be chained without gaps to the extent
possible starting from slot 4, channel 0.
● The startup time of the ET 200PA SMART must be allowed to elapse (at least 10 seconds).
● The physical characteristics of the transducer must be observed. Different transitions of the
input signals (rise time, spikes, ...) can have different effects on the accuracy of the time
stamping.
Limitation
During the following events, the accuracy of time stamping may worsen:
● Processing of diagnostics
● Firmware update
● Reading of I&M data
● Other acyclic services
Scope
The accuracy of the time stamping applies throughout the chain.
Functions
7.4 Time stamping of the input signals with IM 650
ET 200PA SMART
Operating Instructions, 06/2019, A5E34192013-AB 77
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