Siemens simatic ET 200MP - Page 71

Response times
B.1 Response times of the ET 200MP
Interface module IM 155-5 MF HF (6ES7155-5MU00-0CN0)
70 Equipment Manual, 11/2023, A5E53268530-AA
Example configuration for the calculation of the backplane bus cycle time
The following are used in the example:
Table B- 1 Example configuration for the calculation of the backplane bus cycle time
I/O module Output data
in bytes
Input data
in bytes
Number of out-
put addresses
Number of input
addresses
Analog output module AQ 4xU/I ST
8
-
1
-
Analog output module AQ 4xU/I ST with value
status
8 1 1 1
Digital output module DQ 32x24VDC/0.5A ST
with value status
4
4
1
1
Digital input module DI 32x24VDC HF
-
4
-
1
Analog input module AI 8xU/I/RTD/TC ST
-
16
-
1
Sum
20
25
3
4
Example calculation of the backplane bus cycle time
Backplane bus cycle time in μs:
• (20 + 3) x 0.0668 + 1.6131 = 3.1495 ≈ 4 μs (rounded up)
plus
• (25 + 4) x 0.0959 + 2.5901 = 5.3712 ≈ 6 μs (rounded up)
plus
• Operating system processing time 500 μs
Result of backplane bus cycle time
Backplane bus cycle time = 510 μs
Calculating the response time
It is necessary to differentiate between two cases when calculating the response time of the
IM 155-5 MF HF:
• Case 1: The configured update time is greater than/equal to the backplane bus cycle time.
Then:
Response time in μs = backplane bus cycle time + configured update time
• Case 2: The configured update time is less than the backplane bus cycle time.
Then:
Response time in μs = backplane bus cycle time + (configured update time x (backplane
bus cycle time / configured update time)).
If the division of backplane bus cycle time / configured update time does not return an
integer without remainder, an additional configured update time must be added next to
the integer in the bracket.