PID-Feature computes with outdated temperature values

[Wintespe]

PROBLEM DESCRIPTION

A clear and concise description of what the problem is.

This problem report refers to the PID-feature implemented in xdrv_49_pid.ino.

The PID algorithm is called at the time intervals specified by the PID-command PidUpdateSecs. The temperature for the algorithm is updated by TelePeriod time slice.
If the time interval of TelePeriod is greater then the time interval from PidUpdateSecs the temperature value for the PID algorithm is outdated.

Code analysis
To run the PID algorithm, the function

void PIDEverySecond()
   ...
   PIDRun();
   ...

is called.

The temperature for the algorithm is transmitted within the function

void PIDShowSensor()
  ...
   Pid.pid.setPv(temperature, Pid.last_pv_update_secs);
   ...

If the time interval of TelePeriod is greater then the time interval from PidUpdateSecs
the temperature value for the PID algorithm is outdated.

To fix the problem change:

void PIDEverySecond() {
  static int sec_counter = 0; // overflow after 70 years, ok
  Pid.current_time_secs++;    // increment time
  //AddLog(LOG_LEVEL_INFO, PSTR("PIDEverySecond sec_counter: %d"), sec_counter );

  // run the pid algorithm if Pid.run_pid_now is true or if the right number of seconds has passed or if too long has
  // elapsed since last pv update. If too long has elapsed the the algorithm will deal with that.
  if (Pid.run_pid_now  ||  Pid.current_time_secs - Pid.last_pv_update_secs > Pid.max_interval  ||  (Pid.update_secs != 0 && sec_counter++ % Pid.update_secs  ==  0)) {
    PIDRun();
    Pid.run_pid_now = false;
  }
}

to

void PIDEverySecond() {
  static int sec_counter = 0; // overflow after 70 years, ok
  Pid.current_time_secs++;    // increment time
  //AddLog(LOG_LEVEL_INFO, PSTR("PIDEverySecond sec_counter: %d"), sec_counter );

  // run the pid algorithm if Pid.run_pid_now is true or if the right number of seconds has passed or if too long has
  // elapsed since last pv update. If too long has elapsed the the algorithm will deal with that.
  if (Pid.run_pid_now  ||  Pid.current_time_secs - Pid.last_pv_update_secs > Pid.max_interval  ||  (Pid.update_secs != 0 && sec_counter++ % Pid.update_secs  ==  0)) {
    if (Pid.run_pid_now == false) PIDShowSensor(); // set actual process value
    PIDRun();
    Pid.run_pid_now = false;
  }
}

by adding the line

if (Pid.run_pid_now == false) PIDShowSensor(); // set actual process value

That calls P IDShowSensor() if it wasn't triggered by PIDShowSensor() itself.

REQUESTED INFORMATION

Make sure your have performed every step and checked the applicable boxes before submitting your issue. Thank you!

• Read the Contributing Guide and Policy and the Code of Conduct
• Searched the problem in issues
• Searched the problem in discussions
• Searched the problem in the docs
• Searched the problem in the chat
• Device used (e.g., Sonoff Basic): NodeMcu
• Tasmota binary firmware version number used: 11.0.2 and above
  • Pre-compiled
  • Self-compiled
• Flashing tools used: Tasmitizer
• Provide the output of command: Backlog Template; Module; GPIO 255:

  Configuration output here:
na

• If using rules, provide the output of this command: Backlog Rule1; Rule2; Rule3:

  Rules output here:
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• Provide the output of this command: Status 0:

  STATUS 0 output here:
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• Set weblog to 4 and then, when you experience your issue, provide the output of the Console log:

  Console output here:
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TO REPRODUCE

Steps to reproduce the behavior:
na

EXPECTED BEHAVIOUR

A clear and concise description of what you expected to happen.

The PID algorithm should not run with outdated temperature data.

SCREENSHOTS

If applicable, add screenshots to help explain your problem.

TelePeriod 300
PidUpdateSecs 1
The picture shows a time/temperature diagram of a step function (setpoint 25 ->30 °C) after the software fix.

ADDITIONAL CONTEXT

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(Please, remember to close the issue when the problem has been addressed)

[arendst]

Thx.

[Wintespe]

Thanks for the effort