SLA (Safely Limited Acceleration)

SLA description for drive option Functional Safety 3.

Description

SLA, when active, monitors the acceleration and ensures that it stays in an acceleration window. The acceleration window is described by the unsigned parameter a_SLA where -a_SLA defines the lower limit and +a_SLA defines the upper limit. If the acceleration leaves the acceleration window, a configurable fault reaction will be activated.

Number of Instances

One instance per axis.

Function Input / Output Variables

 

 

Inputs

• SLA Activate can be triggered by FSoE or safe digital inputs (must be mapped)
• Safe acceleration: signal from safe feedback

Outputs

• SLA Active: logical status of the SLA function
• Fault Activate: activate fault reaction

Activation

Activation by FSoE	For a drive profile overview, see FSoE (➜ # 1, FSoE). For setup and handling, see the AKD2G EtherCAT Manual.
Activation by safe digital inputs	To review the enclosure and wiring instructions, see Enclosure, wiring (➜ # 1, Enclosure, wiring). To see technical data for the safe inputs, see Technical Data (➜ # 1, Technical Data). For notes on activation by safe inputs, see Activation by Safety Digital Inputs (➜ # 1, Activation By Safe Digital Inputs).

Timing

Related Parameters

Safety parameters

Name	Variables	Default	Parameter
Function Activation	-	0 (Never active)	see "AXIS#.SAFEPARAM.SLA​.FUNCTIONACTIVATION"
Safe Input	-	0 (Not used)	see "AXIS#.SAFEPARAM.SLA​.SAFEINPUT"
FSoE	-	0 (Not used)	see "AXIS#.SAFEPARAM.SLA.FSOE"
Acceleration Limit	a_SLA	1 (Acc user units)	see "AXIS#.SAFEPARAM.SLA​.ACCLIMIT"
Fault Reaction	-	1 (STO)	see "AXIS#.SAFEPARAM.SLA​.FAULTREACTION"

Diagnostic parameters

Name	Variables	Default	Parameter
Function Active Status	-	-	see "AXIS#.SAFE.SLA.ACTIVE"
Function Internal Status	-	-	see "AXIS#.SAFE.SLA.INTERNALSTATE"

State Diagram

SLA is active if internal state is "Monitoring (1)" or "Fault reaction (2)".

 

Setup in WorkBench

Select the drive and open the Safety Parameterization view see "Parameters Editor".

Choose the axis (1), category (2) and the SLA function (3).

Fault Reaction / Failure Messages

SLA has a configurable fault reaction. STO is used by default but can be replaced by SS1 Instance 1 or SS2 Instance 1. When the fault reaction is activated, SLA remains active and the internal state (AXIS#.SAFE.SLA.INTERNALSTATE) is set to failed state (2).

Safety State / Status Signals

The signal AXIS#.SAFE.SLA.ACTIVE can be monitored by safe digital outputs with OSSD pulses see "OSSD". The status signal must be mapped to the safe digital output. Two outputs can be combined to a dual channel output. For parameter description refer to Functional Safety Parameter Reference.

Safety Properties

Refer to (➜ # 1, Safety Properties Overview).