Performance Values For Link-Up And Update; Table 12- 3 Typical Values For The User Program Part - Siemens SIMATIC S7-400H System Manual

Link-up and update
12.4 Time monitoring
12.4.3

Performance values for link-up and update

User program share T
The user program share T
calculated using the following formula:
T
P15_AWP
The table below shows the derived times for some typical values in work memory data.
Table 12- 3
Work memory data
500 KB
1 MB
2 MB
5 MB
10 MB
The following assumptions were made for this formula:
● 80% of the data blocks are modified prior to delaying the interrupts of priority classes >
● For active or queued communication functions, allowance is made for an update time of
166
of the maximum inhibit time for priority classes > 15
P15_AWP
in ms = 0.7 x size of DBs in work memory in KB + 75
Typical values for the user program part
15.
In particular for fail-safe systems, this calculated value must be more precise to avoid any
timeout of driver blocks (see section Determining the monitoring times (Page 159)).
approximately 100 ms per MB in the work memory occupied by data blocks.
Depending on the communication load of your automation system, you will need to add or
deduct a value when you set T
of the maximum inhibit time for priority classes > 15 can be
P15_AWP
T
P15_AWP
220 ms
400 ms
0.8 s
1.8 s
3.6 s
.
P15_AWP
System Manual, 03/2012, A5E00267695-11
S7-400H