Technical data

10.3 Runtimes of the Communication OBs
The "runtime" is the processing time of the special function
organization blocks; the time from calling a block to its termination
can be much greater if it is interrupted by higher priority activities
(e.g. updating timers, etc.).
Special function OB
Block
name
CPU 922 CPU 928 CPU 928B CPU 946/
947
CPU 948
OB 200/
initialize
230 ms 130 ms 130 ms 128 ms 90 ms
OB 202/
send
806
µs (294 µs
basic time
+ 16
µs/word);
118
µs if a
warning occurs
666
µs (250 µs
basic time
+ 13
µs/word);
115
µs if a
warning occurs
696
µs (280 µs
basic time
+ 13
µs/word);
145
µs if a
warning occurs
762
µs (426 µs
basic time
+ 21
µs/
double word);
243
µs if a
warning occurs
542
µs (220 µs
basic time
+ 19
µs/
double word);
110
µs if a
warning occurs
OB 203/ send test
72
µs50 µs80 µs 207µs115 µs
OB 204/ receive
825
µs (281 µs
basic time
+ 17
µs/word);
115
µs if a
warning occurs
660
µs (244 µs
basic time
+ 13
µs/word);
98
µs if a
warning occurs
690
µs (274 µs
basic time
+ 13
µs/word);
128
µs if a
warning occurs
772
µs (421 µs
basic time
+ 22
µs/
double word);
243
µs if a
warning occurs
506
µs (218 µs
basic time
+ 18
µs/
double word);
132
µs if a
warning occurs
OB 205/
receive test
70
µs48 µs78 µs 223 µs120 µs
The runtimes listed in Table 10-6 assume that of four CPUs inserted
in a rack, only the CPU whose runtimes are being measured accesses
the SIMATIC S5 bus. If other CPUs use the bus intensively, the
runtime increases particularly for the send/receive functions.
Table 10-6 Runtimes of the communication OBs
10
Runtimes of the Communication OBs
CPU 928B Programming Guide
C79000-B8576-C898-01
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