SF_TwoHandControlTypeIII

The following description is valid for the function block SF_TwoHandControlTypeIII_V1_0z, Version 1.0z (where z = 0 to 9).

Short description

The safety-related SF_TwoHandControlTypeIII function block evaluates the switching behavior of a type III two-hand control device connected to the Safety Logic Controller.

This involves evaluating the switching states of both the buttons on the two-hand control device. The S_TwoHandOut output only becomes SAFETRUE if both inputs switch from SAFEFALSE to SAFETRUE within 500 ms, either simultaneously or consecutively (if both buttons on the two-hand control device are pressed after being not actuated before).

NOTE:

The used type III two-hand control device must comply with the requirements set out by EN 574.

NOTE:

Unlike the type III two-hand control device described here, evaluation by the type II version takes place without consideration of a specific duration within which both buttons must be actuated.

Function block inputs

Click the corresponding hyperlinks to obtain detailed information on the items below.

Name	Short description	Value
Activate	State-controlled input for activating the function block. Data type: BOOL Initial value: FALSE NOTE: While function block activation is taking place (with input Activate = TRUE), both inputs must show the SAFEFALSE state. This means that none of the buttons on the two-hand control device must be actuated. Otherwise, the function block detects this as an error (output Error = TRUE).	FALSE: Function block inactive TRUE: Function block activated
S_Button1 and S_Button2	State-controlled inputs for evaluating the connected two-hand control device. Data type: SAFEBOOL Initial value: SAFEFALSE	SAFEFALSE: Button not pressed SAFETRUE: Button is pressed

Function block outputs

Name	Short description	Value
Ready	Output for signaling "Function block activated/not activated". Data type: BOOL	FALSE: Function block is not activated (Activate = FALSE) and all outputs of the function block are switched to FALSE/SAFEFALSE. TRUE: Function block is activated (Activate = TRUE) and the output parameters represent the state of the safety-related function.
S_TwoHandOut	Control signal for stopping (stop request) or starting and maintaining machine operation. Data type: SAFEBOOL	SAFEFALSE: S_TwoHandOut switches to SAFEFALSE if the function block has not been activated or the buttons have not been actuated or have been actuated incorrectly (i.e., after 500 ms have elapsed) or an error has been detected. SAFETRUE: S_TwoHandOut is SAFETRUE if the function block has been activated and the buttons have been actuated correctly and no errors have been detected.
Error	Output for error message. Data type: BOOL	FALSE: No error is present. TRUE: The function block has detected an error: During function block activation (with input Activate = TRUE), either one input at least was in the SAFETRUE state or the time offset when the state of the inputs was switching to SAFETRUE was greater than 500 ms. The S_TwoHandOut output switches to SAFEFALSE as a result. To leave the error state, both inputs S_Button1 and S_Button2 must show the SAFEFALSE state.
DiagCode	Output for diagnostic message. Data type: WORD	Diagnostic message of the function block. The possible values are listed and described in the topic "Diagnostic codes".

Signal sequence diagram

This diagram is based on a typical type III two-hand control application.

NOTE:

The signal sequence diagrams in this documentation possibly omit particular diagnostic codes. For example, a diagnostic code is possibly not shown if the related function block state is a temporary transition state and only active for one cycle of the Safety Logic Controller.

Only typical input signal combinations are illustrated. Other signal combinations are possible.

0	The function block is not yet activated (Activate = FALSE). As a result, all outputs are FALSE or SAFEFALSE.
1	Function block activated by Activate = TRUE. At this point, the two buttons are not actuated (S_Button1 and S_Button2 = SAFEFALSE). Both inputs must be SAFEFALSE during activation of the function block, so the Error output remains FALSE.
2	Button 2 (on S_Button2) is actuated, which starts the monitoring time. Button 1 is also pressed within the required period of 500 ms. When S_Button1 switches to SAFETRUE, the condition for two-hand control is met and the S_TwoHandOut output becomes SAFETRUE.
3	The S_TwoHandOut output becomes SAFEFALSE, as S_Button1 and S_Button2 switch to SAFEFALSE within a short time of each other (buttons are released).
4	The button on S_Button1 is now actuated again. The monitoring time begins.
5	Monitoring time runs without button 2 having been pressed. Therefore, the S_TwoHandOut output remains in the defined safe state SAFEFALSE and an error is displayed at the Error output as a result of the TRUE status.
6	Button 1 is released again, which means that the SAFEFALSE state is now present at both inputs. This causes the error message at Error to be reset: Error becomes FALSE.
7	The function block is deactivated: Activate switches to FALSE. Button 2 is pressed while the function block is inactive. This change in state does not start the monitoring time, however, as the function block has not been activated.
8	Function block is activated again (Activate becomes TRUE again). The signal combination at the inputs (S_Button1 = SAFEFALSE and S_Button2 = SAFETRUE) at the time when the function block is activated again leads to an error message (Error = TRUE, S_TwoHandOut = SAFEFALSE). Both inputs must be SAFEFALSE when the function block is being activated.
9	The error message is "reset", as S_Button1 and S_Button2 are now in the SAFEFALSE state (neither button is actuated).
10	Both buttons are actuated again (within a period of 500 ms), the condition for two-hand control is fulfilled, and S_TwoHandOut switches to SAFETRUE again.

Application example

This example shows the connection of a type III two-hand control device with the safety-related SF_TwoHandControlTypeIII function block.

Each of the two buttons has both an N/C and an N/O contact and is connected to safety-related input device SDI 1 via a two-channel arrangement.

The two resulting signals monitored for antivalence are each assigned to global I/O variables and connected to the function block inputs S_Button1 and S_Button2 for evaluation

Further Information:

The details and notes for this application example must also be taken into account.

NOTE:

The S_TwoHandOut enable output of the SF_TwoHandControlTypeIII function block is connected to an output terminal of the application, either directly or via other safety-related functions/function blocks.

Connect the S_TwoHandOut enable output of the SF_TwoHandControlTypeIII function block to the S_OutControl input of the EDM function block, for example, thus implementing a two-channel output connection.

Further Information:

For more detailed information, refer to the description of the corresponding safety-related function block.

S1	Button 1
S2	Button 2
	See note above the illustration.

Detailed information

Additional information is available in the following sections: