-

CTUD / CTUD_S

CTUD_S

Type Function block

Available as standard (non-safety-related) and safety-related type (*_S). For the safety-related type, the safety-related data types (SAFE*) are expected at the formal parameters.
Description Counts up or down. In case of a rising edge at the input CU, CV is increased by one. In case of a rising edge at the input CD, CV is decreased by one. If CV = PV, QU is set to TRUE. If CV = 0, QD is set to TRUE.

If RESET = TRUE, the counter is initialized to 0. If LOAD = TRUE, the counter is initialized to PV. To enable counting, RESET and LOAD must be FALSE. Otherwise the counter will always be re-initialized.
Notes
  • The inputs CU, CD, RESET, LOAD and the outputs QU and QD can be negated.

    Note: The negation of formal parameters is not supported in safety-related code (SNOLD).

  • Function blocks have to be instantiated. The instance name of the function block has to be declared in the 'Variables' table of the POU where the FB is going to be used. The instance name must be unique within the POU.
Parameters Inputs

CU

CD

RESET

LOAD

PV

Outputs

QU

QD

CV