Application Response Time

At a Glance

The application response time is a logical response time which does not take into account the filtering time or the response of the sensor and actuator interfaces.

This is the time elapsed between acquiring an input and setting an output on the INTERBUS bus.

Illustration

The following example illustrates the application response time.

Response Time Example

The following table gives an example of a response time measured for the configuration of a specific bus.

Number of words used			CPU mode	INTERBUS_S scan time (ms)	PLC scan time (ms)			Response time measured (ms)
%IW	%QW	PCP	CPU mode	INTERBUS_S scan time (ms)	average	min.	max.	average	min.	max.
56	56	2	Cyclic	4.8	5	2	13	39	30	77
56	56	2	Periodic	4.8	25	-	-	74	60	101
103	118	5	Cyclic	9.7	4	2	11	80	58	117
128	128	5	Cyclic	11.4	6	3	12	88	68	135

Calculation of the Response Time

The following formula is used to calculate the maximum response time.

Tmax (ms)= 2*Tplc_max + 9*Tibs + Tinput + Tsoft, where:
- Tplc_max = maximum PLC scan time (ms),
- Tibs = IBS scan time (ms),
- Tinput = input delay time (ms) = 3 ms,
- Tsoft = software scan time = 5 ms.

NOTE: The response time depends on the scan times of the PLC and INTERBUS bus. The formula above provides an approximate value for response times in the most unfavourable conditions.