Implementation of safety requirements from applicable standards

The function block evaluates the signals of a three-stage, manually actuated enable switch.

• Switching stage 1: Off function for the switch (manual control not actuated)

• Switching stage 2: Enabling function (manual control actuated as far as central position)

• Switching stage 3: Off function for the switch (manual control actuated past the central position)

The enable switch you use must meet the specified requirements (refer also to "Requirements to the enable switch" in the topic titled "Functional description").

Only when a signal change from switching stage 1 to switching stage 2 is detected at inputs S_EnableSwitchCh1 and S_EnableSwitchCh2, the S_EnableSwitchOut output switches from SAFEFALSE to SAFETRUE and retain this state until switching stage 2 is no longer detected.

You must select the corresponding operating mode (limitation of the speed of motion, kinetic energy or range of motion) outside of the SF_EnableSwitch function block.

The state of the selected operating mode is evaluated by the function block at input S_SafetyActive.

Only when the state SAFETRUE is signaled at the S_SafetyActive input, the S_EnableSwitchOut output can switch to SAFETRUE depending on the signal combination at the inputs S_EnableSwitchCh1 and S_EnableSwitchCh2.

The Reset input supports the function of the manual reset device.

The function block supports a restart inhibit after a valid signal combination has returned at inputs S_EnableSwitchCh1 and S_EnableSwitchCh2, i.e., if S_EnableSwitchCh1 and S_EnableSwitchCh2 show the signal combination for switching stage 1.

To remove an active restart inhibit, a signal change from FALSE to TRUE is required at the Reset input (positive edge).

You are responsible for planning and implementing the restart behavior according to your risk analysis.

To prevent an unintended restart, you may need to perform an additional function start once the safety-related function has been reset. This will depend on both the results of the risk analysis and the signal path of the reset signal.

A SAFETRUE signal at the S_EnableSwitchOut output alone must not be used to initiate the start of the machine. An additional intentional start command, which is independent of the enable switch(es), is required for this. Every person inside the zone of operation must carry an enable switch, which can be used to help prevent a machine state change.

Refer to the hazard message below this table.

Single-channel or two-channel connection must be established depending on the category.