Detailed Description

The CTDOperator is a rising edge counter operator, or CTD counter as referenced by IEC 61131-3 in PLC.

The CTDOperator output (Q) is set to true after the predefined number (PV) of rising edges have been detected in the input (CD).

Arguments

When operator is used inside a signal its default input is automatically tied to signal's InternalValue or previous operator's output. Its default output is automatically tied to next operator's input or to signal's Value. See also CDP Operator Usage In CDP Signals.

Example

Below are the example plots for CTDOperator(PV=5) input (CU, cyan), count down value (CD, orange) and output (Q, yellow).

Actual Processing Code of the CTDOperator

unsigned int CTDOperator<T>::Process()
{
  if (!m_PV || !m_LD || !m_Q)
    return STATUS_ERROR;

  if ((bool)*m_LD)
  {
    *m_CV = (T)*m_PV;
    *m_LD = false;
  }
  bool CD = (bool)*m_CD;
  if (CD && m_oldCD != CD && ((T)*m_CV > 0))
    *m_CV = (T)*m_CV - 1;
  *m_Q = ((T)*m_CV == 0);
  m_oldCD = CD;

  return STATUS_OK;
}