What operating modes are supported by the SoMachine Basic PID controller?

• PID mode
• AT + PID mode
• AT mode
• Word address
  

  PID Mode

  The simple PID controller mode is active by default when the PID controller starts up. The gain values Kp, Ti, and Td to be specified in the PID tab must be known in advance to successfully control the process. You can choose the corrector type of the controller (PID or PI) in the PID tab of the PID Assistant screen. If the PI corrector type is selected, the derivative time Td field is disabled.

  Using PID mode, the Auto-Tuning function is disabled and the AT tab of the Assistant Configuration screen is therefore unavailable.

  AT + PID Mode

  In this mode, the Auto-Tuning function is active when the PID controller starts up. The Auto-Tuning function then calculates the gain values Kp, Ti, and Td and the type of PID action. At the end of the Auto-Tuning sequence, the controller switches to PID mode for the adjusted setpoint, using the parameters calculated by Auto-Tuning.

  If the Auto-Tuning algorithm detects an error:
• No PID parameter is calculated.
• The Auto-Tuning output is set to the output that was applied to the process before starting Auto-Tuning.
• An error message appears in the List of PID States drop-down list.
• The PID control is cancelled.
• While in AT + PID mode, the transition from Auto-Tuning to PID mode is automatic and seamless.
  AT Mode
  In this mode, the Auto-Tuning function is active when the PID controller starts up and automatically calculates both the gain values Kp, Ti, and Td and the type of PID action. After convergence of the Auto-Tuning process and successful completion with the determination of the Kp, Ti, and Td parameters and the type of PID action (or after detection of an error in the Auto-Tuning algorithm), the Auto-Tuning numerical output is set to 0 and the Auto-Tuning Complete message appears in the List of PID States drop-down. The PID controller then stops and waits. The calculated Kp, Ti, and Td PID coefficients are available in their respective memory words (%MWx).
  Word Address
  This PID mode is selected by assigning the desired value to the word address associated with this selection:
• %MWxx = 0: The controller is disabled.
• %MWxx = 1: The controller operates in simple PID mode.
• %MWxx = 2: The controller operates in AT+ PID mode.
• %MWxx = 3: The controller operates in AT mode only.
• %MWxx = 4: The controller operates in simple PID mode, with PI corrector type.
• This mode word address enables you to manage the PID controller operating mode with the application, thus making it possible to adapt to your requirements.

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Released for:Schneider Electric Vietnam