The Profisafe Safety Function Response Time (Sfrt); Profidrive On Profisafe; General Information On Profidrive On Profisafe - Danfoss Vacon OPTEA Operating Manual

VACON® NXP Advanced Safety Options
Operating Guide
Table 48: Description of the Parts of the Watchdog Time
Symbol Name
DAT Device Acknowledgment Time
HAT Host Acknowledgment Time
BT Bus Cycle Time
The F-Parameter F WD Time must have a value that is slightly greater than the sum of DAT, HAT, and two times the bus transfer
time. It is recommended not to exceed the calculated value by more than 30%. Setting a shorter watchdog time does not have an
effect on the safety of a system, but it can cause a fault and make the AC drive trip.
For example, if HAT is 4 ms and the PROFIBUS cycle time is 3 ms, F WD Time should be set to:
F WD Time = (DAT + HAT + 2 × BT) × 1 . 3 = (70 ms + 4 ms + 2 × 3 ms) × 1 . 3 = 104 ms
For example, if HAT is 4 ms and the PROFINET cycle time is 4 ms, F WD Time should be set to:
F WD Time = (DAT + HAT + 2 × BT) × 1 . 3 = (70 ms + 4 ms + 2 × 4 ms) × 1 . 3 = 110 ms
If there is extreme electromagnetic interference, the communication systems use retry mechanisms to increase the robustness of
the system. Before setting the F WD Time, it is recommended to find the number of retries of each connection and adjust the mini-
mum watchdog time if necessary.

7.1.5.3 The PROFIsafe Safety Function Response Time (SFRT)

PROFIsafe specifies a safety function response time (SFRT), during which the safety system must react to a fault in the system. The
SFRT includes all individual delays, including the bus transfer times. All of these elements have minimum and maximum delays, and
the actual delay is likely to be somewhere in between these values. For safety reasons every communication cycle has its own
watchdog time WDTimei after which the safe state is activated if a fault occurs in that communication cycle.
To calculate the safety function response time, use this formula:
n
∑
SFRT = WCDT + max
i
i = 1
i = 1,2..,n
SFRT = Safety Function Response Time
WCDTi = Worst Case Delay Time of entity i
WDTimei = Watchdog Time of entity i. See chapter
Adding the worst case delay times for components of the VACON
Table 49: The Delays and Watchdog Times of a VACON
Device
The complete AC drive system

7.1.6 PROFIdrive on PROFIsafe

7.1.6.1 General Information on PROFIdrive on PROFIsafe

The PROFIdrive on PROFIsafe telegrams are mapped according to the PROFIdrive on PROFIsafe amendment. The selected data for
controlling the safety functions is included in the PROFIsafe frame.
For the AC drive to fully comply with PROFIdrive on PROFIsafe, a compatible drive application must be used, for example the Multi-
purpose Control Application, APFIFF06.
Some values of some parameters in the Advanced safety option board are not compatible with PROFIdrive on PROFIsafe. The
Advanced safety option board allows more detailed or different behavior for some safety functions than what is mentioned in the
PROFIdrive on PROFIsafe amendment.
Danfoss A/S © 2021.06
(WDTime − WCDT )
i i
7.1.5.2 PROFIsafe Watchdog
Safety System
®
Worst case delay time
70 ms
N O T I C E
Description
70 ms for the complete AC drive system
Application-specific
The bus cycle time
Time.
safety system gives the total Worst Case Delay Time.
®
Watchdog time
Recommended 150 ms or larger
AQ319736045637en-000101 / DPD01798 | 115
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