Time-Of-Day Synchronization; Data Record Routing - Siemens SIMATIC NET S7-400 Equipment Manual

Application and functions
1.4 Performance data
Note
Calling program blocks SFCs and SFBs
For SFCs 11, 12, 13, 51, 55, 56, 57, 58, 59 and 103 as well as SFB 52 and 53, several calls are
necessary. The time required to process the job depends on load, round-trip time and
transmission speed. If these SFCs are called in a loop within one cycle, the cycle time could be
exceeded.
Exceptions:
• SFC51 requires only one call if it is used for reading the diagnostics data in a diagnostics
interrupt (SFC51 with parameter 'partial system status list' 0xB1 and 0xB3).
• For SFB54 (receive interrupt with SFB54 "RALRM"), only one call is necessary.
Blocks for DPV1 (according to the PNO standard)
• SFB52 RDREC "Read data record from a DP slave" corresponds to SFC59 in terms of
function
• SFB53 WRREC "Write data record to a DP slave" corresponds to SFC58 in terms of function
• SFB54 ALARM "Read interrupt information from a DP slave" - call in an interrupt OB
PNO: PROFIBUS Users Organization
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1.4.6

Time-of-day synchronization

The CP 4435 forwards timeofday synchronization frames in the following directions:
1. From the CPU via the CP to PROFIBUS if the local CPU is the time master or this station is
synchronized via a different LAN and the timeofday synchronization frame is forwarded to
PROFIBUS for the synchronization of further stations.
2. From PROFIBUS via the CP to the CPU if a remote station is time master, for example:
– a remote CPU 41x with PROFIBUS interface (for example, CP 4435)
– a remote PC with CP 5412 / 5613 / 5614
Note
Transmission speed and synchronization interval
With transmission rates < 1.5 Mbps, we recommend that you configure a synchronization
interval of at least 10 s.
1.4.7

Data record routing

A maximum of 11 connections can be established simultaneously to PA field devices at any
one time.
PDM can, however, use several connections to one PA field device (for more information,
refer to the manual /6/ (Page 51)).
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Equipment Manual, 01/2023, C79000-G8976-C162-10
CP 443-5 Extended