Signals
What this tool does
Ziegler–Nichols and Cohen–Coon settings from an ultimate-gain test or a reaction curve. This page says what the tool is for, in plain language. The working formula stays on the signed-in tool.
When to use it
Open PID loop tuning when this is the job: Ziegler–Nichols and Cohen–Coon settings from an ultimate-gain test or a reaction curve. That is usually a loop check, a range change, or a signal that does not match the panel.
Step-by-step
- Open PID loop tuning from the tool list.
- Fill Rule, Mode, Time unit, Process gain K from the instrument, the drawing, or the job record. Use the unit shown beside each field.
- Fill the remaining fields the same way. Skip a field only when the screen marks it optional.
- Run Calculate when that control is on the page, then read every result row and any warning.
- Check the result against the site procedure and the manufacturer data before you change a range, a wire, a setpoint, or a weight.
- This help page is public. Opening the tool still requires a Pro session.
Inputs
- Rule
- Choose the Rule that matches the instrument, the drawing, or the job. Choices include Ziegler–Nichols ultimate, Ziegler–Nichols reaction, Cohen–Coon.
- Mode
- Choose the Mode that matches the instrument, the drawing, or the job. Choices include P, PI, PID.
- Time unit
- Choose the Time unit that matches the instrument, the drawing, or the job. Choices include Minutes, Seconds.
- Process gain K
- Process gain K is the value you read from the instrument, the drawing, or the job record.
- Dead time L
- Dead time L is the value you read from the instrument, the drawing, or the job record.
- Time constant T
- Time constant T is the value you read from the instrument, the drawing, or the job record.
- Ultimate gain Ku
- Ultimate gain Ku is the value you read from the instrument, the drawing, or the job record.
- Ultimate period Pu
- Ultimate period Pu is the value you read from the instrument, the drawing, or the job record.
Results
- Result
- The reported value for PID loop tuning. Use the unit printed on that row.
- Warnings
- A warning means an entry is incomplete or outside what this tool will stand behind. Recheck the inputs and the site procedure.
Common mistakes
- Swapping the lower range and the upper range, or typing the live reading into a range field.
- Treating a square-root flow signal as if it were a linear span.
- Changing a range while a warning is still on the screen.
- Do not treat a result from PID loop tuning as a substitute for the site procedure or the manufacturer data.
Standards references
These are the standards and public references named on this tool. Clause numbers appear only when the catalog already cites them.
- Ziegler and Nichols, Transactions of the ASME, vol. 64, 1942
- Cohen and Coon, Transactions of the ASME, vol. 75, 1953
Offline and access
This engine can run offline after the server has cached it for the signed-in account.
A free session can read this help page. The tool card shows the name and the short summary. Opening the tool requires Pro.