PIDSnap

Turn a photo of a trend into the next tuning value

PIDSnap is software for industrial PID loops. Photograph the trend screen and the faceplate. It reads the shape, classifies the loop signature, and — where tuning is the answer — computes each next value to type, one observed change at a time.

Run a free check

Step 1: your loop is misbehaving A trend showing an under-damped process variable oscillating around setpoint through several peaks without settling. 1 Your loop is misbehaving Hunting, overshooting, never settling Four peaks and still going PVSP
Your loop is misbehaving. PV is hunting and the output is driving it.
Step 2: photograph the trend and the faceplate The same misbehaving trend, captured by photographing the operator screen. 2 Snap the trend The screen and the faceplate, as they are A photo of the screen is enough PVSP
A photo from your phone. No connection needed.
Step 3: PIDSnap classifies the problem The oscillating trend, read as aggressive tuning with the gain too high for the loop's dead time. 3 PIDSnap says what it is Named, and whether tuning can fix it Aggressive tuning: gain too high PVSP
PIDSnap classifies the shape — and computes the next value, or tells you tuning cannot help.
Step 4: one change at a time, with the value to type The previous oscillating response shown faintly behind the new damped response, with the exact gain change that produced it. 4 One change at a time The value to type, in your own units Take the gain from 0.40 to 0.28 the faint trace is where it was before PVSP
Reduce the gain, re-snap, confirm it worked.

And when tuning is not the answer

Valve stiction: a limit cycle tuning cannot remove A trend in which the controller output ramps smoothly while the process variable moves in abrupt steps past where it was asked to go, producing a cycle of constant amplitude that does not decay. MECHANICAL — NOT TUNING Valve stiction The output ramps. The PV jumps. PVOP The cycle holds its amplitude instead ofdecaying — that is what separates stictionfrom a loop that is merely over-tuned. Put the loop in manual and it stops.
Valve stiction — the controller output ramps smoothly while the process variable moves in abrupt steps. Put the loop in manual and the cycle stops. No tuning session is worth buying until the valve is fixed.
Output saturation: the controller pinned against its limit A trend in which the controller output sits flat at its upper limit while the process variable stalls below setpoint, so no tuning change reaches the valve. MECHANICAL — NOT TUNING Output saturation The output pins at 100%. The PV stalls below setpoint. The output is flat on its limit and the PVis still short of setpoint. While the outputis pinned, no tuning change reaches the valve. Put the loop in manual and it stays pinned.
Output saturation — the output sits pinned at its limit while the process variable stalls below setpoint. The controller is not in control, and no tuning change reaches the valve until the limit lets go.

What it reads

Every trend PIDSnap receives is classified against a closed set of loop signatures.

Valve stiction producing a limit cycle Trend showing valve stiction: the controller output ramps smoothly while the process variable moves in abrupt steps, producing a limit cycle that does not decay. high low PV SP Output PIDSnap time Valve stiction
Controller output saturated at its limit Trend showing controller output saturation: the output sits flat against its upper limit while the process variable never reaches setpoint. high low PV SP Output PIDSnap time Output saturation
An over-tuned loop hunting after a setpoint change Trend of an over-tuned PID loop: the process variable hunts for several cycles after a setpoint change before settling. high low PV SP Output PIDSnap time Aggressive tuning
A healthy control loop response Trend of a healthy PID loop: after a setpoint step the process variable overshoots slightly and settles within two peaks. high low PV SP Output PIDSnap time Healthy response

What you get

Pre-flight check

Deterministic checks against the loop's configuration, run before you touch anything. Derivative on a fast loop, reset faster than the dead time, a valve running wide open — the things no test will fix. Free, unlimited, no signup.

Trend analysis

Upload a photo of the trend. PIDSnap classifies the shape and reports plainly when the signature is mechanical and no tuning session is worth buying.

Step-by-step tuning

One change at a time, phrased in your controller's own units and direction, with the value to type. Paid after the first session. If the problem is not tuning, the session is not worth buying.

Run a free PIDSnap check

Two photos, no signup. The pre-flight check finds structural problems no amount of tuning will fix — before you touch the controller.

Run a free check