IFM Electronic AC402S - Page 98

SmartPLC SafeLine AC4S with fieldbus interfaces
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Step 4: Calculate the worst-case response time of the safety function
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The worst-case process safety time
► Calculate the worst case on the basis of the calculated and measured values.
 Without safe cross communication:
AS-i output
Local output
FSoE slave output
AS-i input
-
-
T(WD_FSoE)
Local input
-
-
T(WD_FSoE)
FSoE slave
input
T(WD_FSoE) +
2*T(SafetyTask) +
15 ms
T(WD_FSoE) +
2*T(SafetyTask) +
8 ms
T(WD_FSoE_in) +
2*T(SafetyTask) +
2*tMaxRespTimeMS(FSoE_out)
 With safe cross communication:
To device 2
From device 1
AS-i output
Local output
FSoE slave output
AS-i input
MAX(
30 ms +
2*T(SafetyTask_Dev1) +
tMaxRespTimeMS(SafetyNetVars)
+ 2*T(SafetyTask_Dev2) +
15 ms;
T(WD_SafetyNetVars) +
2*T(SafetyTask_Dev2) +
15 ms)
MAX(
30 ms +
2*T(SafetyTask_Dev1) +
tMaxRespTimeMS(SafetyNetVars)
+ 2*T(SafetyTask_Dev2) +
8 ms;
T(WD_SafetyNetVars) +
2*T(SafetyTask_Dev2) +
8 ms)
MAX(
30 ms +
2*T(SafetyTask_Dev1) +
tMaxRespTimeMS(SafetyNetVars)
+ 2*T(SafetyTask_Dev2) +
tMaxRespTimeMS(FSoE_out);
T(WD_SafetyNetVars) +
2*T(SafetyTask_Dev2) +
tMaxRespTimeMS(FSoE_out);
T(WD_FSoE_out))
Local input
MAX(
16 ms +
2*T(SafetyTask_Dev1) +
tMaxRespTimeMS(SafetyNetVars)
+ 2*T(SafetyTask_Dev2) +
15 ms;
T(WD_SafetyNetVars) +
2*T(SafetyTask_Dev2) +
15 ms)
MAX(
16 ms +
2*T(SafetyTask_Dev1) +
tMaxRespTimeMS(SafetyNetVars)
+ 2*T(SafetyTask_Dev2) +
8 ms;
T(WD_SafetyNetVars) +
2*T(SafetyTask_Dev2) +
8 ms)
MAX(
16 ms +
2*T(SafetyTask_Dev1) +
tMaxRespTimeMS(SafetyNetVars)
+ 2*T(SafetyTask_Dev2) +
tMaxRespTimeMS(FSoE_out);
T(WD_SafetyNetVars) +
2*T(SafetyTask_Dev2) +
tMaxRespTimeMS(FSoE_out);
T(WD_FSoE_out))
FSoE slave
input
MAX(
T(WD_FSoE_in) +
2*T(SafetyTask_Dev1) +
tMaxRespTimeMS(SafetyNetVars)
+ 2*T(SafetyTask_Dev2) +
15 ms;
T(WD_SafetyNetVars) +
2*T(SafetyTask_Dev2) +
15 ms)
MAX(
T(WD_FSoE_in) +
2*T(SafetyTask_Dev1) +
tMaxRespTimeMS(SafetyNetVars)
+ 2*T(SafetyTask_Dev2) +
8 ms;
T(WD_SafetyNetVars) +
2*T(SafetyTask_Dev2) +
8 ms)
MAX(
T(WD_FSoE_in) +
2*T(SafetyTask_Dev1) +
tMaxRespTimeMS(SafetyNetVars)
+ 2*T(SafetyTask_Dev2) +
tMaxRespTimeMS(FSoE_out);
T(WD_SafetyNetVars) +
2*T(SafetyTask_Dev2) +
tMaxRespTimeMS(FSoE_out);
T(WD_FSoE_out))
The response times of the output side have to be added to the calculated worst-case times
(T(output) + T(actuator)).