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Rockwell Automation Publication 35-UM001A-EN-P - May 2022
Chapter 6 Safety Functions
When a safety fault occurs in the module, the STO function is forced to the
Safe State, which is the Torque Disabled state. In this case, the configured STO
Delay value is bypassed and torque is immediately disabled.
the timing of STO and torque attributes in response to STO activation by a
Safety Fault.
Clearing a Safety Fault requires correcting the fault condition, then a 0 to 1
transition on Request Reset.
Figure 42 - STO with Safety Fault
Safe Stop 1 Function
The Safe Stop 1 (SS1) function signals the configured SS1 Stop Action Source to
initiate a stopping action, then the safety module monitors the stop. When the
Safe Stop 1 is complete, STO is activated and torque is disabled. If the drive
does not complete the stop within the limits that are configured in the Safe
Stop 1 function, an SS1 Fault is annunciated.
Safe Stop 1 Activation
Safe Stop 1 can be initiated by one or more sources:
•
SS1 Request – Setting the Safety Output Assembly Tag
(
devicename
:SO.SS1Request1 = 1)
•
Limit Active – Reserved for future use
•
Connection Loss – Loss of connection to the safety controller
•
Connection Idle – Safety controller in program mode
When SS1 is activated, all sources of activation are stored in an attribute as a
bit mask and the attribute can then be read to determine the causes of an SS1
activation.
shows the operation of the SS1 activation attribute. The
SS1 Activation attribute can be read with a message instruction (see attribute
289 in Armor PowerFlex AC Drives CIP Objects and Attributes Reference Data,
publication
Unlike the STO function, SS1 does not get activated by a safety fault.
SO.Reset Request
(1)
SI.Torque Disabled
(3)
SI.Restart Required
(3)
SI.STO Active
(3)
SI. Safety Fault
(1)
STO Activation
(2)
Safety Fault
0x04 = Safety Stop Fault
Torque Disabled
Restart Required
Always Required to Reset a Fault
Disable Torque
(1) Safety Output Assembly
(2) Safe Stop Function Attribute
(3) Safety Input Assembly
Fault Cleared
ATTENTION:
If STO activation by a safety fault occurs, the configured
STO Delay time is ignored, and torque is immediately disabled.
