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SignalP/PID - RG350861

Description

This block implements a PID control algorithm.  It has a single output.

The error between the setpoint and feedback is determined and this is used along with information stored from previous invocations to compute the proportional, integral and derivative terms.  These terms are summed together to form the output.  The PID Enable input can override this computation and force an output of zero.  The Integral Enable input can eliminate the integral term from the output summation.

The block has facilities for reducing integral wind-up.  If the Feedback is outside the Pos FB Limit or the Neg FB Limit, the integrator is held at its current value.  The integrator is also held if the magnitude of the proportional term exceeds the PG Limit.

Although all of the inputs may be connected to other function blocks in the system, a new output is computed only when the Feedback input receives a message.  Furthermore, the Feedback input should receive messages on a regular basis (the block is designed to tolerate timing jitter but should not be left without a feedback input for long periods).

Parameters

Feedback	Feedback to the block.  Expects a value (-100% to +100%).

Setpoint	Setpoint for the block.  Expects a value (-100% to +100%).

PID Enable	Enables the PID output.  Expects Disable (false) or Enable (true).

Integral Enable	Enables the integral term.  Expects Disable (false) or Enable (true).

Proportional	Sets the proportional gain.  Expects a value between 0 and 30 (100% = 30).

Derivative	Sets the derivative time constant.  Expects a value between -5 and 5 seconds (100% = 5 seconds).

Integral	Sets the integral gain.  Expects a value between 0.1 and 15 seconds -1 (100% = 15 seconds -1).

Pos FB Limit	Sets the positive feedback limit.  Expects a value (-100% to +100%).

Neg FB Limit	Sets the negative feedback limit.  Expects a value (-100% to +100%).

PG Limit	Sets the proportional gain limit.  Expects a value (0% to +100%).

Get Output	Returns the current value of the output:  -100% to +100%.

Get Setpoint	Returns the current value of the setpoint:  -100% to +100%.

Get PID Enable	Returns the current state of the PID enable:  Disabled (false) or Enabled (true).

Get Integral Enable	Returns the current state of the integral enable:  Disabled (false) or Enabled (true).

Get Proportional	Returns the current value of proportional gain:  0 to 30.

Get Derivative	Returns the current value of derivative gain:  -5 to 5 seconds.

Get Integral	Returns the current value of integral gain:  0.1 to 15 seconds -1.

Get Pos FB Limit	Returns the current value of the positive feedback limit:  -100% to +100%.

Get Neg FB Limit	Returns the current value of the negative feedback limit: -100% to +100%.

Get PG Limit	Returns the current value of the proportional gain limit:  -100% to +100%.


Description

This block implements a PID control algorithm.  It has a single output.

The error between the setpoint and feedback is determined and this is used along with information stored from previous invocations to compute the proportional, integral and derivative terms.  These terms are summed together to form the output.  The PID Enable input can override this computation and force an output of zero.  The Integral Enable input can eliminate the integral term from the output summation.

The block has facilities for reducing integral wind-up.  If the Feedback is outside the Pos FB Limit or the Neg FB Limit, the integrator is held at its current value.  The integrator is also held if the magnitude of the proportional term exceeds the PG Limit.

Although all of the inputs may be connected to other function blocks in the system, a new output is computed only when the Feedback input receives a message.  Furthermore, the Feedback input should receive messages on a regular basis (the block is designed to tolerate timing jitter but should not be left without a feedback input for long periods).


Parameters

Feedback	Feedback to the block.  Expects a value (-100% to +100%).

Setpoint	Setpoint for the block.  Expects a value (-100% to +100%).

PID Enable	Enables the PID output.  Expects Disable (false) or Enable (true).

Integral Enable	Enables the integral term.  Expects Disable (false) or Enable (true).

Proportional	Sets the proportional gain.  Expects a value between 0 and 30 (100% = 30).

Derivative	Sets the derivative time constant.  Expects a value between -5 and 5 seconds (100% = 5 seconds).

Integral	Sets the integral gain.  Expects a value between 0.1 and 15 seconds -1 (100% = 15 seconds -1).

Pos FB Limit	Sets the positive feedback limit.  Expects a value (-100% to +100%).

Neg FB Limit	Sets the negative feedback limit.  Expects a value (-100% to +100%).

PG Limit	Sets the proportional gain limit.  Expects a value (0% to +100%).

Get Output	Returns the current value of the output:  -100% to +100%.

Get Setpoint	Returns the current value of the setpoint:  -100% to +100%.

Get PID Enable	Returns the current state of the PID enable:  Disabled (false) or Enabled (true).

Get Integral Enable	Returns the current state of the integral enable:  Disabled (false) or Enabled (true).

Get Proportional	Returns the current value of proportional gain:  0 to 30.

Get Derivative	Returns the current value of derivative gain:  -5 to 5 seconds.

Get Integral	Returns the current value of integral gain:  0.1 to 15 seconds -1.

Get Pos FB Limit	Returns the current value of the positive feedback limit:  -100% to +100%.

Get Neg FB Limit	Returns the current value of the negative feedback limit: -100% to +100%.

Get PG Limit	Returns the current value of the proportional gain limit:  -100% to +100%.