PROFINET/Ethernet
5.3 Timing and runtimes
Power Line Booster
76
Operating Instructions, 11/2019, A5E36203125A-AG
Figure 5-4
Graphic for determining the PROFINET times
For PDS applications, it is the maximum number of possible slaves in the segment that is the
decisive factor for determining the PROFINET/PROFIsafe watchdog times, because the
likelihood of faults and the times for sounding of the carrier frequencies grow exponentially
with the number of slaves.
Note
The following configurations apply when using PROFINET
Set the PN watchdog time depending on the slaves as follows:
•
40 slaves: 1600 ms (25 update cycles at 64 ms PN update time)
•
20 slaves: 928 ms (29 update cycles at 32 ms PN update time)
•
10 slaves: 656 ms (41 update cycles at 16 ms PN update time)
•
1 slave: 265 ms (33 update cycles at 8 ms PN update time)
Note
With typical PLB applications (e.g. electric monorail system), we can assume that several
vehicles do not leave the communication segments at the same time. This means we
assume that no more than one vehicle and therefore one PLB slave exits the communication
segment within a period of 1 s. If multiple PLB slaves were to exit the communication
segment at the same time due to the application, the PLB cycle time may be significantly
longer and the maximum latency time would therefore be exceeded.
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