Functional description

The SF_Reset function block executes the function "manual resetting" within an application. To this end, it evaluates the following signals:

the request signal for the manual resetting at the ResetIn input,
the status signal "operation stop" from the standard PLC at the OperationStop input.

The function block can be configured via the following inputs:

The RisingEdge input specifies whether the rising edge or the falling edge (according to EN ISO 13849-1) of the request signal for manual resetting is evaluated.
The EdgeMonitoring input is used to monitor the duration of the request signal (only with parameterizing for the evaluation of the falling edge). In doing so, it is monitored whether the falling edge occurs within the time slot set after activating the control device for the manual resetting.
The MinEdgeTime and MaxEdgeTime inputs are only relevant if the evaluation of the falling edge of the request signal is parameterized. When monitoring is set (EdgeMonitoring = TRUE), they specify the time slot set (in seconds) for the minimum and/or maximum duration of the request signal at the ResetIn input; i.e., the falling edge must occur within this time slot.

The function block switches the request signal at the ResetOut output in accordance with the applied input signals.

Function block behavior in the event of errors

Detected error states are signaled at the Error output. Resetting and/or removing errors, which can occur with the SF_Reset function block, depends on the error category.

When initializing the function block, faulty parameterization settings at the inputs is checked:
- Is the maximum duration set less than or equal to the minimum duration (MaxEdgeTime <= MinEdgeTime) of the request signal when a duration monitoring of the request signal is configured?
- Are the duration monitoring of the request signal (EdgeMonitoring = TRUE) and the evaluation of the rising edge at the ResetIn input (RisingEdge = TRUE) parameterized at the same time?
Removing such parameterization errors is done by applying valid values at the respective inputs.

When the duration monitoring of the request signal (EdgeMonitoring = TRUE) is configured, an error is signaled when it comes to an undercutting of the minimum duration or an exceeding of the maximum duration. Such an error is reset:
- When the falling edge has occurred before the minimum duration MinEdgeTime has elapsed: by switching the request signal at the ResetIn input to TRUE.
- When no falling edge has occurred before the maximum duration MaxEdgeTime has elapsed: by a rising edge of the request signal at the ResetIn input from FALSE to TRUE (the request signal at the ResetIn input must be previously switched to FALSE).