Placing an Engineered Template

How an engineered template gets onto a drawing, and why the drop stops to ask you questions first.

Which simulation? This page is about placing a unit. Running one uses the client-side, single-unit, PLC-style scan simulation in your browser — not the server-side biokinetic process simulation described under Simulation.

Before you start

• You need a drawing open in the P&ID editor (/draw).
• The engineered template must be visible to you. Five units are published and visible to everyone who passes the plan, tenant and allocation gates; Chemical Dosing and Storm Overflow Chamber are draft (awaiting owner sign-off), so only a company Admin or Owner (or a SuperAdmin) sees those two in the stencil. See Why you may not see them in the stencil yet.
• Engineered templates sit in the category Process Units/engineered, and their names carry the suffix (Engineered Unit).

The three steps

1. Drag the template onto the canvas

Drag the template out of the stencil and drop it where you want the unit to sit, exactly as you would any other template. The drop position is recorded at that moment and reused later, so you do not have to drop it twice.

No screenshot: the Engineered category shows "No templates published yet" in the demo tenant this guide is captured against, so this screen cannot be shown honestly here.

2. Confirm key parameters

Nothing is drawn yet. For an engineered template the drop is intercepted, and a panel titled Confirm key parameters opens on the right of the canvas area. It carries the template's name, a line saying how many values are confirmed on placement, one field per asked parameter, and two buttons: Place and generate and Cancel.

No screenshot: the Engineered category shows "No templates published yet" in the demo tenant this guide is captured against, so this screen cannot be shown honestly here.

Why it asks. An engineered template generates control logic, an I/O schedule and a calculation sheet from a resolved model. A handful of answers decide the shape of all of it — how many pumps, which control method, what the chamber area is — and those cannot sensibly be guessed and corrected later, because correcting them means regenerating the drawing. Everything else keeps the template's own default and is edited afterwards in the workspace. The panel says so in as many words:

N values are confirmed on placement. Everything else is edited in the template workspace.

What it asks. Only the template's own ask-on-drop parameters, in schema order. Each unit declares its own list — they are given on the unit pages — and the count is deliberately kept small:

Unit	Asked on drop
Wastewater Pumping Station	9 for a new station, 14 for an existing one
Flow Balancing Tank	10 for a new vessel, 15 for an existing one
Aeration Blower Set	10 for a new set, 14 for an existing one
Flow to Full Treatment Control	15, the same list either way
Storm Tank	16, the same list either way

New versus existing. Three of the five published units carry a new / existing parameter. Choosing existing adds a few surveyed figures to the form — the ones you would measure on a site that already has the asset, such as the real main diameter, the real tank dimensions or the real duty point — and the panel re-derives its field list the moment you change that answer. The other two units (Flow to Full Treatment Control and Storm Tank) deliberately have no such parameter, so their list is the same in both cases.

Field types. The panel renders each parameter with the control its type calls for — a number spinner with the parameter's own unit as a hint, a searchable dropdown for an enumerated choice, a yes/no switch for a boolean, a text box otherwise.

Cancel closes the panel and places nothing. You can drag the template out again.

3. Place and generate

Place and generate hands your answers back to the drop handler, which then:

1. builds the unit's P&ID at the position you dropped it, through the live template registry;
2. wraps the placed elements in a movable group, and selects it, so dragging any part moves the whole unit;
3. registers a template instance against that group — its slug, its template version, the answers you confirmed and the template's default setpoints.

That third step is what distinguishes an engineered placement from an ordinary one. The instance record is what the workspace reads, what the port chips publish from, and what survives a reload of the drawing.

No screenshot: the Engineered category shows "No templates published yet" in the demo tenant this guide is captured against, so this screen cannot be shown honestly here.

After placing

Port value chips

A placed engineered instance shows port value chips on the canvas: the process values it reads at its inbound ports off the west edge, the values it publishes at its outbound ports off the east edge, and its signal set under the south edge. The reading of each chip follows the port's declared medium, so a water port reads in l/s and DN, and an air port does not pretend to.

The Template instance properties section

Select any element inside the placed unit — a pump, a valve, the panel — and the properties panel gains a Template instance section. It resolves upwards from whatever you selected to the instance that owns it, so you do not have to click the group container. It shows:

• Inputs (read) — the values the unit reads at its inlet port.
• Outputs (published) — what its outlet and signal ports publish downstream.
• Open template workspace — the button that opens the workspace.

About the inlet values. Today they are the values the instance itself was placed with, and every input row says so ("from instance"). Reading an inlet from a project design basis, or from the connected upstream instance's outlet, is not built yet — so nothing on this panel claims a source it does not have.

Opening the workspace

Two routes, same destination:

• Double-click the placed unit on the canvas.
• Use Open template workspace in the Template instance properties section.

Both go to /drawings/<drawingId>/units/<instanceId>. Carry on at The Template Workspace.

A workspace link needs its drawing open. The placed instance lives in the drawing's own model in your browser tab. A workspace URL pasted into a fresh tab cannot reach a drawing that has not been loaded there; the workspace says so plainly — "That template instance is not on this drawing" — and offers a link back. Open the drawing first, then the workspace from it.

What we could not verify from the code

The behaviours above are read from the implementation. Nobody has yet recorded watching this flow run in a browser, so anything that depends on live rendering — how the panel reflows at a narrow window, how long the drop takes to draw a large unit, whether the port chips stay legible at low zoom — is not described here, and should not be assumed from this page.