Interface

Opening the protective equipment

If the protective equipment properly connected to the function block is opened, the function block sets enable output S_Guard to SAFEFALSE (safe state).

Closing the protective equipment

If opened protective equipment in the application is closed, the function block can optionally (see Start interlock ) ensure within the safe control system that the release signal is not set to SAFETRUE solely by this closing. This requires another manual action on input parameter Reset (see Start interlock ).

Interlocking device

The function block fully supports a 2-stage interlocking device.

On a 3-stage interlocking device, the function block supports the transition from the second to the third stage and back again. On a 4-stage interlocking device, the function block supports the transition from the third to the fourth stage and back again. All other stages must be implemented in the safety application.

Guard locking device

The protective equipment's guard locking device should be programmed in a separate safety function block or in the safety application since this function block simply grants or revokes its approval. Maintaining the approval in conjunction with the guard locking device and standstill monitoring must be viewed in close connection with the safety application.

Application with 1 position switch

1 position switch (1-channel)

If 1 position switch (1-channel) is used in the protective equipment, the signal must be connected to the function block input parameter S_GuardSwitch1 over a safe input device. In addition, a graphic connection between both input parameters ("S_GuardSwitch1" and "S_GuardSwitch2") must be established in the safety application. This allows both signal inputs to be controlled by the same signal.

The function block enable output is only set to SAFETRUE if both input parameters (S_GuardSwitch1 and S_GuardSwitch2) indicate state SAFETRUE and the remaining input signal combination is valid for this as well.

1 position switch (2-channel)

If 1 position switch (2-channel) is used in the protective equipment, the signals must be connected to a safe input device individually. In the safety application, the signals of the position switch must be checked for dual-channel redundancy (e.g. using safe devices or other function blocks such as SF_Antivalent of SF_Equivalent). The signal resulting from this check be connected to function block input parameter "S_GuardSwitch1". In addition, a graphic connection between both input parameters ("S_GuardSwitch1" and "S_GuardSwitch2") must be established in the safety application. This allows both signal inputs to be controlled by the same signal.

The function block enable output is only set to SAFETRUE if both input parameters (S_GuardSwitch1 and S_GuardSwitch2) indicate state SAFETRUE and the remaining input signal combination is valid for this as well.

Application with 2 position switches

2 position switches (1-channel)

If 2 position switches (1-channel) are used in the protective equipment, the signals must be connected to one or more safe input devices individually. One of these signals must be connected to input parameter S_GuardSwitch1 of the function block. The other signal must be connected to the second function block input parameter S_GuardSwitch2.

The function block enable output is only set to SAFETRUE if both input parameters (S_GuardSwitch1 and S_GuardSwitch2) indicate state SAFETRUE and the remaining input signal combination is valid for this as well.

2 position switches (2-channel)

If 2 position switches (2-channel) are used in the protective equipment, the 4 signals must be connected to one or more safe input devices individually. In the safety application, each signal of the position switch must be checked for dual-channel redundancy (e.g. using safe devices or other function blocks such as SF_Antivalent of SF_Equivalent). A signal must result from this check for each of the 2 position switches. One of these signals must be connected to input parameter S_GuardSwitch1 of the function block. The other signal must be connected to the second function block input parameter S_GuardSwitch2.

The function block enable output is only set to SAFETRUE if both input parameters (S_GuardSwitch1 and S_GuardSwitch2) indicate state SAFETRUE and the remaining input signal combination is valid for this as well.

Quantity and layout of supported position switches

The function block supports protective equipment with 1 or 2 mechanical or non-mechanical position switches. Depending on the CAT or SIL requirements, 1-channel or 2-channel position switches with equivalent or antivalent arrangement of switching contacts are required.

The function block processes one signal per position switch, which results from checking the dual-channel redundancy on 2-channel position switches.

The function block does not monitor the dual-channel redundancy (line control) or equivalence/antivalence of the signals. This monitoring must be implemented in the safety application using safe devices or other function blocks (SF_Antivalent or SF_Equivalent), for example.

Typical timing diagrams

1) Start

2) Wait

3) Normal operation

4) Error

1) Normal operation

2) Error

Function block specific error codes

Function block-specific status codes (no error)