Using the safety functions

Timing diagrams

Timing diagram for STO-function without SBC

../../../../../_images/timing_sto2.png

Timing diagram for STO-function with SBC-function

../../../../../_images/timing_sto-sbc2.png

Truth table for digital inputs

Digital input STO-SBC 1

Digital input STO-SBC 2

Internal fault

Safety Statusword

Error entry

0

0

no

1

0

1

no

1

“SfeDilvd”

1

0

no

1

“SfeDilvd”

1

1

no

0

0

0

yes

1

“SfeFault”

Diagnostic functions

Fault diagnostics

The safety circuit has two integrated diagnostic functions:

  • Comparing safety digital input statuses. The fault is activated after 100ms discrepancy of the STO-SBC inputs. In case a fault is detected, the servo drive will enter Fault state and indicate a fault “SfeDilvd” in the Error Report object.

  • During the activation of the STO-SBC function the servo drive verifies that the two channels of the module are internally operating correctly. In case an internal fault is detected, the servo drive will enter Fault state and indicate a fault “SfeFault” in the Error Report object.

Fault reaction

In case a fault has been detected, the drive will stay in fault state until manual reset has been given and the brake is closed.

Resetting diagnostic faults

To reset a fault condition, please:

  • request STO/SBC (for example by activating the emergency stop device) and

  • reset the fault

Attention

When the fault resetting was not successful, power cycle the servo drive and investigate the reason for the failure.

STO-SBC status register

The Safety Statusword indicates the current state of safety functions and Safety Digital Input Diagnostics shows the state of the Safety Module inputs.

Index

Name

Descriptions

0x6621

Safety Statusword

Subindex:

1 - Bit 1: STO status is the first bit of byte

2 - Bit 2: SBC status is the first bit of byte

STO/SBC status:

0: is not active

1: is active

0x2611

Safety Digital Input

Subindex:

1 - Input 1:

2 - Input 2:

Input 1/2:

0: Input is low

1: Input is high

Important

Using the SBC function while running the motor may damage the brake due to mechanical stress. During normal operation it is recommended to activate STO-SBC after the motor has come to a halt e.g. by introducing a delay with an external safety logic device such as a safety timer. This way an equivalent of SS1 with time monitoring is implemented.

Attention

The STO-function does not provide electrical isolation from the mains supply. If electrical changes need to be carried out on the system (e.g. modifying the motor cabling), the servo drive shall be completely isolated from mains supply with a mechanical switch.