Siemens SIMATIC NET CP 343-1 Manuel d'utilisateur télécharger pdf (Page 38)

5 Performance Data / Operation

B−38

CP 343-1 Advancedfor Industrial Ethernet / Manual Part B

Release 06/2008

C79000-G8976-C202-04

S CPU cycle time

As a result, the reaction times for cyclic PROFINET CBA interconnections may

exceed the configured value for the update time. You should therefore check the

achievable reaction time during commissioning.

Since reaction times t 50 ms cannot be guaranteed, you should not set a

transmission frequency x 32 ms for cyclic interconnections.

Reaction times of 50 ms can be achieved at CPU cycle times of t 5 ms and with

the following configuration limits:

S t 200 bytes inputs and at the same time

S t 200 bytes outputs

S maximum of 200 interconnection distributed on 32 partners

With higher CPU cycle times, the PROFINET CBA function block (FB88) should be

called more often in the user program.

Note

The values of the utilization parameters of the selected components displayed in

the network view by SIMATIC iMap with the “Edit / Check utilization” function

relate to the data exchange as far as the CP. They do not apply to data access

from the user program.

Execution times of the PN_InOut (FB88) function block

To calculate the CPU cycle times (OB1) in CBA operation, the execution time for

the FB PN_InOut (FB88) required for processing on the S7-300 / C7-300 CPU is

the decisive factor.

Table 5-10

Duration

length of the interface DB / bytes

512 1024 2048 4096

at least / μs 122 123 123 123

maximum / μs 2330 2330 2400 2400

typical / μs 1100 1270 1400 1435

From the table, you can see that the OB1 cycle is extended by at least 122 μs and

by a maximum of 2400 μs.

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Siemens SIMATIC NET CP 343-1 Manuel d'utilisateur Page 38