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SF_GuardLocking (Safety Guard Interlocking with Locking)

Tip

The version of the function block as described here corresponds to the latest version of the function block in Version list of function blocks.

Applicable safety standards

SF_GuardLocking is a certified PLCopen function block. For detailed information about applied standards, see "PLCopen – Technical Committee 5 – Safety Software".

Important

The requirements listed in the standards must be fulfilled by the user.

Interface description

This FB controls the entrance to a hazardous area by means of an interlocked guard with locking (four-stage interlocking).

Important

The requirements listed in the standards must be fulfilled by the user.

Table 45. VAR_INPUT

Name

Data Type

Initial Value

Description, parameter values

Activate

BOOL

FALSE

General input parameters

S_GuardMonitoring

SAFEBOOL

FALSE

Variable

Monitors the interlocked disconnecting guard

FALSE: Guard open

TRUE: Guard closed.

S_SafetyActive

SAFEBOOL

FALSE

Variable.

Status of the hazardous area (EDM), for example, based on velocity monitoring or safe fallback delay time

FALSE: Machine is in non-safe status

TRUE: Machine is in safe status

S_GuardLock

SAFEBOOL

FALSE

Variable

Status of the mechanical interlocked guard.

FALSE: The guard is not locked.

TRUE: The guard is locked.

UnlockRequest

BOOL

FALSE

Variable.

Intervention by the operator – request to unlock the guard

FALSE: No request

TRUE: Request made.

S_StartReset

SAFEBOOL

FALSE

General input parameters

S_AutoReset

SAFEBOOL

FALSE

General input parameters

Reset

BOOL

FALSE

General input parameters: Also used for the request that the guard should be locked again. The characteristic of the signal must comply with a manual reset device.



Table 46. VAR_OUTPUT

Name

Data Type

Initial Value

Description, parameter values

Ready

BOOL

FALSE

General output parameters

S_GuardLocked

SAFEBOOL

FALSE

Interface to the hazardous area which has to be stopped.

FALSE: Not a safe state.

TRUE: Safe state.

S_UnlockGuard

SAFEBOOL

FALSE

Signal to unlock the guard.

FALSE: Close the guard.

TRUE: Unlock the guard.

Error

BOOL

FALSE

General output parameters

DiagCode

WORD

16#0000

Diagnostic codes



Figure 79. Function block: SF_GuardLocking
Function block: SF_GuardLocking


Description of the functionality and safe status

This FB controls a locked guard and monitors the position of the guard and the guard with locking. SF_GuardLocking can be used with a mechanically interlocked switch.

The operator makes a request to gain access to a hazardous area. The guard can only be unlocked if the hazardous area is in a safe state. The guard can be locked when it is closed. The machine can be started when the guard is closed and locked. An open or unlocked guard is detected in the event of a safety-critical situation.

Caution

The S_StartReset and S_AutoReset inputs shall only be activated if it is ensured that no hazardous situation can arise when the S-PLC is started.

Table 47. Function sequence

1.

External

Requirement to bring the hazardous area to a safe condition – not part of this FB

2.

In

Feedback from the relevant hazardous area that it is in a safe state (via S_SafetyActive)

3.

In

Request from the operator to unlock the guard. (via UnlockRequest)

4.

Out

Allow the guard to open.

5.

In

Guard locking of the guard is unlocked (via S_GuardLock). The guard can now be opened. (S_GuardLocked = FALSE)

Operator opens the guard

6.

In

Monitoring of the state of the guard via S_GuardMonitoring. Indicates when the guard is closed again.

7.

In

Operator feedback to reactivate the hazardous area (Reset).

8.

Out

Locking the guard (S_UnlockGuard)

9.

In

Check whether the guard is locked (S_GuardLock)

10.

Out

Hazardous area is ready for operational use (S_GuardLocked = TRUE)

11.

External

Restart operation in the hazardous area.



Status diagram

Figure 80. Status diagram: SF_GuardLocking
Status diagram: SF_GuardLocking


Tip

Note: The transition from any state to the Idle state, initiated by Activate = FALSE, is not shown. In every case, these transitions have the highest priority.

Typical timing diagrams

Figure 81. Timing diagram: SF_GuardLocking
Timing diagram: SF_GuardLocking


Error detection

Static signals at Reset are detected. Errors are detected at the guard switches.

Error behavior

In case of an error event, the outputs S_GuardLocked and S_UnlockGuard are set to FALSE, the DiagCode output shows the relevant error code, and the Error output is set to TRUE.

An error must be acknowledged by a rising trigger edge at the Reset input.

FB-Specific Error and Status Codes

Table 48. FB-specific error codes

DiagCode

Statue Name

Status description and output setting

16#C001

Reset Error 1

Static reset detected in state 8001.

Ready = TRUE

S_GuardLocked = FALSE

S_UnlockGuard = FALSE

Error = TRUE

16#C002

Reset Error 2

Static reset detected in status C004

Ready = TRUE

S_GuardLocked = FALSE

S_UnlockGuard = FALSE

Error = TRUE

16#C003

Reset Error 3

Static reset detected in state 8011.

Ready = TRUE

S_GuardLocked = FALSE

S_UnlockGuard = FALSE

Error = TRUE

16#C004

Safety Lost

No more safe state; guard open or guard locking unlocked

Ready = TRUE

S_GuardLocked = FALSE

S_UnlockGuard = FALSE

Error = TRUE



Table 49. FB-specific status codes (no error)

DiagCode

Statue Name

Status description and output setting

16#0000

Idle

The function block is not active (basic state).

Ready = FALSE

S_GuardLocked = FALSE

S_UnlockGuard = FALSE

Error = FALSE

16#8000

Guard Closed and Locked

The guard is locked.

Ready = TRUE

S_GuardLocked = TRUE

S_UnlockGuard = FALSE

Error = FALSE

16#8001

Init

FB has been activated and initialized.

Ready = TRUE

S_GuardLocked = FALSE

S_UnlockGuard = FALSE

Error = FALSE

16#8003

Wait for Reset

Door is closed and locked; wait for Reset by operator

Ready = TRUE

S_GuardLocked = FALSE

S_UnlockGuard = FALSE

Error = FALSE

16#8011

Wait for operator

Wait for operator to either request an unlock or reset.

Ready = TRUE

S_GuardLocked = FALSE

S_UnlockGuard = FALSE

Error = FALSE

16#8012

Guard open and unlocked

The guard is unlocked and open.

Ready = TRUE

S_GuardLocked = FALSE

S_UnlockGuard = TRUE

Error = FALSE

16#8013

Guard Closed but Unlocked

The guard is closed but unlocked.

Ready = TRUE

S_GuardLocked = FALSE

S_UnlockGuard = TRUE

Error = FALSE

16#8014

Safety Return

The S_SafetyActive signal is present; wait for confirmation by operator

Ready = TRUE

S_GuardLocked = FALSE

S_UnlockGuard = FALSE

Error = FALSE