SSM (Safe Speed Monitor)
SSM description for drive option Functional Safety 3.
Description
SSM is a pure monitoring function which has no fault reaction. Once configured, it stays activated monitoring whether the velocity stays within a velocity window or not. The parameter n_UL_SSM defines the upper limit and the parameter n_LL_SSM defines the lower limit of this window.
The SSM function returns a logical status, called InRange, which tells whether the velocity is currently located in the velocity window or not.
Number of Instances
Two instances per axis.
Function Input / Output variables
Input
- Safe velocity: velocity signal from safe feedback
Outputs
- SSM InRange: logical status telling if the velocity is in the range defined by the SSM function
Activation
No activation source. Once configured in the safety parameters, it stays activated.
Related Parameters
Safety parameters
|
Name |
Variables |
Default |
Parameter |
|---|---|---|---|
|
Function Activation |
- |
0 (Never active) |
|
|
Velocity Upper Limit |
n_UL_SSM |
0 (Vel user units) |
|
|
Velocity Lower Limit |
n_LL_SSM |
0 (Vel user units) |
Diagnostic parameters
| Name |
Variables |
Default |
Parameter |
|---|---|---|---|
|
SSM InRange |
- |
- |
|
|
Function Internal Status |
- |
- |
Timing
Setup in WorkBench
Select the drive and open the Safety Parameterization view (see "Parameters Editor").
Choose the axis (1), category (2), SSM function (3) and the instance number (4).
Safety State / Status Signals
The signal AXIS#.SAFE.SSM_#.INRANGE 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).
