6.4.1.1 Watchdog Time
The watchdog time setting depends on the speed of the PROFINET connection and the number of devices.
• Valid range: 67–65535 ms
• Default value: 150 ms
If the safety option does not receive a new valid PROFIsafe telegram within this time, the safety option enters the safe state. The
watchdog time is configured to a value that is long enough to avoid false alarms and short enough to detect errors in communication.
The formula for calculating the minimum watchdog time:
F_WD_TIME = 2 x BT + HAT + DAT
• BT = Bus cycle time
• HAT = Host acknowledgment time
• DAT = Device acknowledgment time
Use the watchdog time to calculate the safety function response time (SFRT) for the system. For more information, see the PROFIsafe
profile description at
www.profibus.com.
6.5 Configuring PROFIsafe with Siemens TIA Portal
This section explains how to configure PROFIsafe communication between VLT® Safety Option MCB 152 and Siemens device with
Siemens TIA Portal.
6.5.1 Configuring the Hardware
Context:
Configure the PROFINET communication with the F-PLC using the VLT® PROFINET MCA 120 Installation Guide.
Configuring the Safety Option
Installation Guide | VLT®Safety Option MCB 152
AN327351953089en-000101 / 130R0578| 45
Danfoss A/S © 2020.02
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