IFM Electronic AC402S Programming Manual page 97

SmartPLC SafeLine AC4S with fieldbus interfaces
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Step 3: Define watchdog times
Safe cross communication and safe fieldbus communication are monitored by means of watchdogs.
Sufficiently long watchdog times have to be selected.
► Determine the watchdog times on the basis of the maximum response times of the safety function
measured ins step 2. ifm recommends the following formulas:

safe cross communication: T(WD_SafetyNetVars) = 2*T(tMaxRespTimeMS)

safe fieldbus communication: T(WD_FSoE) = 2*T(tMaxRespTimeMS)
► Set watchdog times
(Set variable components of the response time (→ S. 99)).
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