Lesson 11 · The whole plant: logic, warehouse and what-ifs

Everything you have learned now works together. Goods arrive, platforms carry them to the warehouse, a VNA truck stores them, lines ask for pallets and the warehouse answers; a heavy truck serves Line 2 and a chained transport on to Repack. You will wire it up, run a shift, read what limits it and compare what-if alternatives.

Time

45 min

Start from

the checkpoint of lesson 10

You will learn

combine timers, conditions on the warehouse, chained waits, variables and a drop-off trigger in one diagram
protect a shared dead end and keep each fleet on its own work
run what-if alternatives, find the limiting resource and export the results

Open your project from lesson 10, or its checkpoint.

The flows

Flow	Path of the material	Who moves it
Inbound	Goods in → WH in (platform), then stored in A01	platforms, then the VNA truck
Line 1	A01 → WH in (retrieved), then WH in → Line 1	the VNA truck, then platforms
Line 2	Goods in → Line 2, then on to Repack after 40 s	the heavy truck only

Guard the annex

The annex is a dead end with one station in it, and three kinds of vehicle now want it: platforms bringing and collecting pallets, and the VNA truck passing through to its aisle. That is the situation of lesson 5, and it fails the same way: two platforms in the stub at once block each other. Without protection this plant jams within minutes.

Draw the zone. In Draw choose Zone (9) and drag from (−13 600, −1 300) to (−10 400, 1 300): it covers the exchange station and the stretch of annex between it and the loop, and stops short of the racks and of the truck's parking. Type the four limits exactly in Properties and name it Annex gate.
Keep the truck's parking where it was. The parking lies 3.5 m beyond the exchange station, outside the zone, so the truck starts clear of it. A station inside a zone is possible, but only when the vehicles inside it have a way out, as lesson 5 explained.

Keep the truck off the goods

By default every fleet may use every station, so the VNA truck could be sent to carry goods from Goods in, which is not its job. Select Goods in and untick VNA in Permitted fleets. Now Goods in is served by the platforms and the heavy truck only.

Rebuild the diagram

Open Plant logic. You will end with three counters and four sequences. Reuse what you can: the Line 2 sequence and the chained transport to Repack stay as they are. Delete the old Line 1 sequence from lesson 7 (timer, condition, mission, counter) and the two warehouse timers from lesson 10, and the skipped variable with them.

Three counters. Add three Plant variable blocks, integers starting at 0: refused (pallets that arrived with no room), starved (times Line 1 asked and found nothing) and delivered (pallets delivered to Line 1).

Inbound

Periodic timer120 sConditionavailable empty cells ≥ 1Generate missionInbound: Goods in → WH inWait for deliveryStoreWH in · A01End sequence

…ConditionnoUpdate variablerefused + 1End sequence

Every two minutes a pallet arrives at Goods in. The condition asks the warehouse first: Available empty cells counts the empty cells that are not already reserved by an order. If there is room, a platform carries the pallet to the exchange station; Wait for delivery waits until it has been unloaded there; Store then asks the truck to put it in the best free cell. If there is no room the pallet is refused and counted.

Line 1 supply

Periodic timer150 s, first after 300Conditionavailable pallets ≥ 1RetrieveWH in · A01Wait for deliveryGenerate missionTo Line 1: WH in → Line 1Wait for deliveryUpdate variabledelivered + 1End sequence

…ConditionnoUpdate variablestarved + 1End sequence

Line 1 first waits five minutes, so some stock exists, then asks every 150 seconds. If a pallet is available, Retrieve brings it to the exchange station, a first Wait for delivery waits for the truck to unload it there, and a platform carries it to Line 1; the second wait lets the sequence count the pallet only once it has really been delivered. If nothing is available, the line is starved and the counter says so.

Line 2 and Repack

Keep these two sequences from lesson 7, but change the Line 2 timer to 240 seconds: the heavy truck is slow, and this is the rate at which it keeps up. The On station drop-off trigger on Line 2, the 40-second Wait and the mission to Repack stay.

What you should see

A valid diagram of about 30 blocks, tidy rows for the four sequences, and the three counters at the side. The Pickup and drop-off step says From Plant logic.

Run a shift

Calm the dice for a fair test. In Simulate, open Disturbances and switch every disturbance off for the comparisons below. Chance would blur the differences you are looking for; you can switch them back on at the end.
Run an hour. Press Start run for 1 h. About 120 missions are completed in the hour, counting every leg (platform transports, the truck's stores and retrievals, the heavy truck's two legs). Around 25 pallets are stored and 20 retrieved, and about 19 reach Line 1. No gridlock.
Read the plant. Open Results. Fleet usage shows the heavy truck and the VNA truck busiest, the platforms close behind; Warehouse shows the stock hovering around 40 pallets with its timeline; and the counters at the bottom of Plant logic read refused 0, starved 0 and delivered about 19. Open 3D view to watch the whole plant, forks included.

Note

Stock rises by about six pallets an hour, because more arrive than leave. Run 8 h and the warehouse fills near the end: refused then starts counting pallets sent away. That is the diagram doing its job, and a number to put in front of whoever plans the inbound flow.

Three what-ifs

Change one thing at a time and run 1 h again each time, restoring the baseline between runs. The table shows what to expect.

A faster heavy truck. In Vehicles, give Heavy custom motion of 80 cm/s on straights, 40 on curves, 40 acceleration and 60 deceleration.
Fewer platforms. Set Platforms to 2 vehicles.
A slower VNA lift. In the VNA fleet's VNA warehouse, halve the lift and lowering speeds to 15 and 20 cm/s.

Run	Completed	Lead time	Queue at the end	Delivered to Line 1
Baseline	120	≈ 240 s	6	19
Faster heavy truck	123	≈ 205 s	6	19
Two platforms	104	≈ 310 s	17	15
Slower VNA lift	117	≈ 250 s	9	18

The lesson of the numbers: the platforms are what holds the plant together. Taking one away costs more than any other change, with the queue nearly tripling, while a faster heavy truck buys a little and a slower lift costs little, because the VNA truck is busy but not the bottleneck. A study like this tells you where to spend: here, on a fourth platform, not on faster lifts.

Warning

These figures describe the model with its default speeds and times. They are good for ranking alternatives, not for promising a number to a customer.

Keep and share the work

Save a copy per variant. Use Project›Duplicate project to keep each alternative worth showing, with a name that says what changed.
Export the evidence. On a finished run, Export (.zip) writes a ZIP with the results as JSON and CSV tables, and PDF writes a report with findings and plans of the run, heatmaps included. Export CSV in the comparison table exports the runs side by side. Every run also stays in the Run archive.
Share the project. Project›Download .sim copy downloads the whole project as a .sim file that anyone can open with Project›Import project: layout, scenario, diagram and warehouse, but not the results.

What you should see

A project that you can save, a comparison table of the what-ifs, a PDF of the baseline and a plant that keeps running without a gridlock.

Try it yourself

Raise the inbound rate to one pallet every 90 s and run 8 hours. When does the warehouse fill, and how many pallets does refused count?
Add a fourth charger and platform: draw the station, tick the charger role, raise the platforms to 4 and compare with the baseline.
Switch the disturbances back on and run the baseline four times. How wide is the spread, and which of the what-ifs is larger than it?

Where to go from here

Draw your own plant on a real floor plan: CAD floor plans imports a DWG or DXF background at the right scale, and everything in this course carries over.
Give stations a 3D model (roller conveyors, racks, machines) in 3D station models and present the plant in 3D.
More focused studies, each with its setup and what to look at, are in the Scenario cookbook.
When something refuses to start or behaves oddly, Troubleshooting and FAQ lists the messages and what they mean.

Checkpoint

The plan at the end of this lesson: the finished plant: loop, repacking spur, heavy bay and warehouse annex, with the annex gate zone

It contains: 11 paths · 10 stations · 2 traffic zones · 1 warehouse aisle · 5 AGVs · 3 fleets · 28 workflow blocks.

Download the checkpoint (aurora-11-capstone.en.sim)

Open it with Project›Import project. It replaces the project you have open, so save yours first (or open it in a new browser tab). Anything you do from here on is a copy: the checkpoint file itself never changes. Use it to continue from here if you skipped a lesson, or to compare your own project with the expected one.