Specifications

Response Times IP 240
12.2 Computing the Response Time
Using channel 1 as example, Figure 12-2 shows which FW slices must be taken into account when
computing the response time.
Figure 12-2. Computing the Response Time
t
reak
=t
ka1/1
+t
kom1
+t
ka2/1
+t
kom2
+t
ka1/
2
t
ka1
= Processing times for
channel 1
t
ka2
= Processing time for
channel 2
t
kom
= Processing times for a
data interchange
t
reak
= Response time
FW reads the count for channel 1.
The actual value has not yet reached the setpoint.
FW reads the count for channel 1.
The actual value has reached the setpoint.
The status bits for channel 1 are updated on the IP 240, an interrupt, where
applicable, is generated and the FW drives the IP outputs.
The firmware releases the data. The new status bits, the new actual value and the
interrupt request bytes can be read out from the IP.
(If new data were transferred to the IP in the preceding FW cycle, the firmware
does not release the data until the next cycle).
t
ka1
t
ka2
t
kom
t
ka1
t
ka2
t
ka1
t
ka2
t
kom
t
kom
t
reak
Channel 1
setpoint reached.
Cycle 2 Cycle 1
The maximum response times are thus as follows:
for channel 1 t
reak.-ka1 max.
= t
ka1/1 max.
+ t
ka2/1 max.
+ t
kom1 max.
+ t
kom2 max.
+ t
ka1/2 max.
for channel 2 t
reak.-ka2 max.
= t
ka2/1 max.
+ t
kom1 max.
+ t
ka1/2 max.
+ t
kom2 max.
+ t
ka2/2 max.
Substitute the maximum value for a data Read for t
kom1 max.
and the maximum value for a data
Write for channel 1 or channel 2 for t
kom2 max.
If the IP 240 is not accessed during positioning or
during a counting cycle, assume t
kom
=0.
The new data are available on the IP 240 when the response time has elapsed, and can be read out
with the next data interchange.
The execution times of the individual slices are discussed in detail in Section 12.3.
12-2 EWA 4NEB 811 6120-02a