Danfoss VLT FC 280 Operating Manual page 67

VLT® Midi Drive FC 280
Operating Guide
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If there is extreme electromagnetic interference, the communication systems use retry mechanisms to increase the robust-
ness of the system. Before setting the F WD time, it is recommended to find the number of retries of each connection and
adjust the minimum watchdog time if necessary.
6.5.2.4 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 WDTime after which the safe state is activated if a fault occurs in that communication cycle.
i
Calculate the safety function response time via the following formula:
n
∑
SFRT = WCDT + max WDTime
i
i = 1 i = 1, 2.., n
SFRT=Safety Function Response Time
WCDT =Worst Case Delay Time of entity i
i
WDTime =Watchdog Time of entity i. See
i
Adding the worst case delay times to the components of the safety system gives the total worst case delay time. See the following
tables.
Table 34: Time Parameters
Device
The complete AC drive system
6.5.2.5 PROFIdrive on PROFIsafe
The drive supports PROFIsafe standard telegram 30. The following sections describe the PROFIdrive on PROFIsafe standard telegram
30 bits. In a PLC program, address the safety functions using bits while not bytes.
Byte 0 is PROFIdrive on PROFIsafe-specific and byte 1 is vendor-specific.
To show the hex values of PROFIsafe status word and PROFIsafe control word on the LCP, use parameter 42-83 Safe Status Word and
parameter 42-82 Safe Control Word. The hex values are used for debugging purpose or transferring the safe control information to a
non-safe control environment.
6.5.2.5.1 PROFIsafe Control Word
Table 35: PROFIsafe Control Word (S_STW1)
Byte
Byte 0
Byte 0
Byte 0
Byte 0
Byte 1
Bits that are not supported are set to 0.
1
Byte 0 Bit 0, STO
• Bit 0.0=0, Safe Torque Off (zero-active).
• Bit 0.0=1, No Safe Torque Off.
Byte 0 Bit 1, SS1
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N O T I C E
− WCDT
i i
6.5.2.3 PROFIsafe Watchdog
Worst case delay time
120 ms
Bit Name
0 STO
1 SS1
2–6 Not supported
7 INTERNAL_EVENT_ACK
0–7 Not supported
Time.
Watchdog time
Recommended 250 ms or larger
(1)
(1)
AQ381425076031en-000101 / 130R1223 | 67
Safety Functions