SSR (Safe Speed Range)

SSR description for drive option Functional Safety 3.

Description

SSR, when activated, monitors the velocity and ensures that it stays in a configured velocity window. The parameter n_UL_SSR defines the upper limit and the parameter n_LL_SSR defines the lower limit of this window. If the velocity leaves the velocity window a configurable fault reaction will be activated.

Once the activation request is received, SSR will become active depending on what occurs first:

  • The time to velocity monitoring is elapsed (t_SSR)
  • The current velocity stays in the configured velocity window for a given amount of time (t_L_SSR)

Optionally, the deceleration ramp can be monitored after some delay (t_D_SSR) to check whether the current velocity is below the computed velocity ramp (a_SSR). If the velocity is above the computed velocity ramp, the fault reaction will be activated.

Number of Instances

Three instances per axis.

Function Input / Output Variables

 

 

Inputs

  • SSR Active can be triggered by FSoE or safe digital inputs (must be mapped)
  • Safe velocity: velocity signal from safe feedback

Outputs

  • SSR Active: logical status of the SSR 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

Timing

Related Parameters

Safety parameters

Name

Variables

Default

Parameter

Function Activation

-

0 (Never active)

AXIS#.SAFEPARAM.SSR_#​.FUNCTIONACTIVATION

Safe Input

-

0 (Not used)

AXIS#.SAFEPARAM.SSR_#​.SAFEINPUT

FSoE

-

0 (Not used)

AXIS#.SAFEPARAM.SSR_#.FSOE

Time To Velocity Monitoring

t_SSR

2 ms

AXIS#.SAFEPARAM.SSR_#​.TIMETOVELMONITORING

Velocity Upper Limit

n_UL_SSR

0 (Vel user units)

AXIS#.SAFEPARAM.SSR_#​.VELUPPERLIMIT

Velocity Lower Limit

n_LL_SSR

0 (Vel user units)

AXIS#.SAFEPARAM.SSR_#​.VELLOWERLIMIT

Time For Velocity in Limits

t_L_SSR

1 ms

AXIS#.SAFEPARAM.SSR_#​.TIMEFORVELINLIMITS

Deceleration Monitoring

-

0 (Disabled)

AXIS#.SAFEPARAM.SSR_#​.DECMONITOREN

Deceleration Limit

a_SSR

0 (Dec user units)

AXIS#.SAFEPARAM.SSR_#​.DECLIMIT

Time Delay Deceleration Monitoring

t_D_SSR

1 ms

AXIS#.SAFEPARAM.SSR_#​.TIMEDELAYDECMONITORING

Fault Reaction

-

1 (STO)

AXIS#.SAFEPARAM.SSR_#​.FAULTREACTION

Diagnostic parameters

Name

Variables

Default

Parameter

Function Active Status

-

-

AXIS#.SAFE.SSR_#.ACTIVE

Function Internal Status

-

-

AXIS#.SAFE.SSR_#.INTERNALSTATE

SSR is active if internal state is "Monitoring (4)" or "Fault reaction (5)".

Setup in WorkBench

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

Choose the axis (1), category (2), SSR function (3) and the instance number (4).

Fault Reaction / Failure Messages

SSR 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, SSR remains active and the internal state
(AXIS#.SAFE.SSR_#.INTERNALSTATE) is set to failed state (5).

Safety State / Status Signals

The signal AXIS#.SAFE.SSR_#.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).