SDI (Safe Direction)

SDIn/SDIp description for drive option Functional Safety 3.

SDIp		SDIn

Description

SDI monitors the direction of movement and activates a configurable fault reaction when a violation occurs. SDI consists of two sub-functions: SDIp (for positive direction) and SDIn (for negative direction). Both functions share

the same position window paramater s_Zero_SDI,
the same velocity limit parameter n_Zero_SDI and
the same configurable fault reaction.

However, they have their own sources of activation and their own delay before monitoring (t_D_SDIp and t_D_SDIn):

When SDIp is activated, the safety module prevents motion in the positive direction. The motion can either be in the negative direction or be stopped.
When SDIn is activated, the safety module prevents motion in the negative direction. The motion can either be in the positive direction or be stopped.
If both functions are activated at the same time, the motion must be stopped.

Number of Instances

One instance per axis.

Function Input / Output Variables

Inputs

SDIp Activate can be triggered by FSoE or safe digital inputs (must be mapped)
SDIn Activate can be triggered by FSoE or safe digital inputs (must be mapped)
Safe pos & vel: position and velocity signal from safe feedback

Outputs

SDIp Motion Active: indicates whether the axis is moving in the positive direction
SDIn Motion Active: indicates whether the axis is moving in the negative direction
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

s_cp defines the safe position which is taken while the function activates. It is used to compute the range of allowed position values that the axis can take while the position monitoring is activated. The range is computed by adding or substracting s_Zero_SDI to/from the parameter s_cp.

Related Parameters

Safety parameters

(➜ # 1)

Name	Variables	Default
Function Activation	-	0 (Never active)
Safe Input SDIp	-	0 (Not used)
FSoE SDIp	-	0 (Not used)
Safe Input SDIn	-	0 (Not used)
FSoE SDIn	-	0 (Not used)
Position Zero Window	s_Zero_SDI	1 (Pos user units)
Velocity Zero Window	n_Zero_SDI	1 (Vel user units)
Time Delay Monitoring SDIp	t_D_SDIp	1 ms
Time Delay Monitoring SDIn	t_D_SDIn	1 ms
Fault Reaction	-	1 (STO)

Diagnostic parameters

Name	Variables	Default	Parameter
SDIp Moving	-	-	(➜ # 1)
SDIp Function Internal Status	-	-	see "AXIS#.SAFE.SDIp.INTERNALSTATE"
SDIn Moving	-	-	(➜ # 1)
SDIn Function Internal Status	-	-	see "AXIS#.SAFE.SDIn.INTERNALSTATE"

State Diagrams

SDIp		SDIn

Setup in WorkBench

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

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

Fault Reaction / Failure Messages

SDI 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, the internal states of SDI (AXIS#.SAFE.SDIp.INTERNALSTATE and AXIS#.SAFE.SDIn.INTERNALSTATE) are set to failed state (4).

Safety State / Status Signals

The signals AXIS#.SAFE.SDIn.MOTIONACTIVE and AXIS#.SAFE.SDIp.MOTIONACTIVE can be monitored by safe digital outputs with OSSD pulses see "OSSD". The status signals must be mapped to the safe digital outputs. 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).