Lesson 6 · Plant logic: your first block diagram

Until now orders arrived at a fixed rate. Real plants do not work like that: lines consume material at their own pace and one event triggers the next. Plant logic lets you describe that with connected blocks, without writing any code.

Open your project from lesson 5, or its checkpoint. Prefer to watch first? Video 04 builds a small diagram.

Sequences and blocks

A diagram is made of blocks joined by connections. A trigger block (a timer, for instance) creates a sequence: an independent token that travels from block to block, waits where a block tells it to wait, and disappears at End sequence or at an output left unconnected. Many sequences can be alive at once, even in the same blocks.

Trigger

starts a sequence: Periodic timer (at a rhythm), On station drop-off (when something is unloaded), On pickup completed (after loading finishes), Cyclic mission (whenever a source is free) or Start (once). See how to request another pickup, optionally after a wait.

Flow

Wait holds the sequence for a time, Prerequisite until a condition is true, Condition chooses between Yes and No.

Missions

Generate mission queues one transport; Wait for delivery waits until the sequence's own mission has been delivered.

Variables

Plant variable and Update variable keep shared counters and flags (next lesson).

Time in a diagram is simulated time: a block that waits 40 seconds waits 40 seconds of the simulation, however fast you run it.

The Line 1 sequence

Line 1 consumes a pallet every 90 seconds. The sequence is three blocks in a row:

1. Open the workspace. Click Plant logic in the header. The diagram is empty and offers Start from an example; ignore it, you will build your own.
2. Add the three blocks. In the Blocks list on the left, click Periodic timer, then Generate mission, then End sequence. Each appears on the diagram. Drag a block by its title to put it where you want it: timer on the left, mission in the middle, end on the right.
3. Connect them. Click the dot on the right of the timer (its output, Continue), then the dot on the left of Generate mission (its input). Do the same from the mission's output to End sequence. Esc cancels a connection in progress. An unconnected Continue would end the sequence too; End sequence makes it explicit, and it is needed to close a branch, because both outputs of a decision must be connected.
4. Configure the timer. Click the timer's title. The panel on the right shows its fields: set Interval (s) to 90 and leave First start after (s) at 0.
5. Configure the mission. Click the mission block. Set Name to Line 1: generated orders will say which block created them. In Block pickups keep only Goods in ticked, and in Block drop-offs keep only Line 1: untick the other two.
6. Read the status line. At the bottom of the diagram the status reads Valid workflow. If something is wrong, it counts the issues and names the block concerned.

The Line 2 sequence

Line 2 consumes more slowly and starts later. Build a second row of three blocks below the first: a Periodic timer with Interval (s) 150 and First start after (s) 30, a Generate mission named Line 2 from Goods in to Line 2 only, and an End sequence. Connect them in order.

The two sequences are independent: they share nothing but the pickup and the fleet, and each fires on its own clock.

Switch it on and run

1. Enable the diagram. Set Order generation to Plant logic at the top left. Until you do, the diagram is a draft and the fixed-rate generator keeps working. Once on, the diagram replaces the fixed rate completely.
2. Check the scenario. In Simulate, the Pickup and drop-off step now reads From Plant logic: pickups, drop-offs and rates are defined in the blocks. The Interval field is gone from Orders, but the fleet and the dispatch rules stay where they were.
3. Run one hour. Press Start run with 1 h. During a run each block shows how many sequences are in it and how many have passed through, and the status line reports the active and completed sequences.

Line 1 asks for 40 orders an hour and Line 2 for 24, so about 64 missions an hour, with the three vehicles at roughly three quarters of their capacity and an empty queue. In the comparison table the Orders column now reads Diagram instead of an interval.

Checkpoint

It contains: 9 paths · 7 stations · 1 traffic zone · 3 AGVs · 6 workflow blocks.

Download the checkpoint (aurora-06-workflow.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.