Siemens SIMATIC S7-400H System Manual page 378

S7-400 cycle and response times
19.7 Examples of calculating the cycle and response times
Calculating the longest response time
● Longest response time
● Delay of inputs and outputs
● All components are installed in the central unit, so DP cycle times can be ignored.
● Case 1: The system sets an output channel of the digital output module after a digital
● Case 2: The system reads in and outputs an analog value. The result is as follows:
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22.5 ms * 2 = 45 ms.
– The maximum input delay of the digital input module SM 421; DI 32×DC 24 V is
4.8 ms per channel
– The output delay of the digital output module SM 422; DO 16×DC 24 V/2A is
negligible.
– Analog input module SM 431; AI 8×13Bit was parameterized for 50 Hz interference
frequency suppression. The result is a conversion time of 25 ms per channel. As
8 channels are active, a cycle time of the analog input module of 200 ms results.
– Analog output module SM 432; AO 8×13Bit was parameterized for operation in the
measuring range 0 ... 10 V. This results in a conversion time of 0.3 ms per channel.
Since 8 channels are active, the result is a cycle time of 2.4 ms. The transient time of
a resistive load of 0.1 ms must be added to this. The result is an analog output
response time of 2.5 ms.
input signal is read in. The result is as follows:
Response time = 45 ms + 4.8 ms = 49.8 ms.
Response time = 45 ms + 200 ms + 2.5 ms = 247.5 ms.
System Manual, 03/2012, A5E00267695-11
S7-400H