PROFINET Recipe Transfer

A laser positioning system can receive a recipe in two ways: the operator enters it on the panel, or the line automation sends it. The two are not alternatives. Most installations use both, with a priority rule defined between them.

Three integration levels

Data structure

Whether the protocol is PROFINET or EtherNet/IP, the exchange is the same in substance: a small bidirectional data block. Its typical content is set out below.

From the line to the system

• Recipe number — or an array of position values sent directly
• Number of active reference lines — how many reference lines are to be set
• Command bit — “start setup”, “return home”, “lasers off”

From the system to the line

• Status — ready / setting up / set / fault
• Progress — how many reference lines are in position
• Fault code — limit exceeded, position not reached, communication lost
• Acknowledge bit — confirmation that the command was received

Why a handshake is necessary

A setup cycle takes seconds; the PLC works in milliseconds. That difference opens a gap between a command being “sent” and being “done”. The handshake closes it.

1. The line writes the commandThe recipe number and the start bit pass to the system.
2. The system acknowledgesIt raises the acknowledge bit. The line then knows the command has been received.
3. The line drops the command bitThis prevents the same command from being processed twice.
4. The system performs the setupThe status stays “setting up” while the progress value updates.
5. The system reports completionThe line now knows every reference line is in position and can move to the next step.

That four-bit loop settles the “I sent the recipe but I do not know whether the machine is ready” question. It matters most on lines that change product automatically.

Define fault conditions in advance

The biggest time sink at commissioning is an exception nobody discussed. Agree these three scenarios up front:

• The requested position falls outside the usable travel. The system rejects the command and returns a fault code. What should the line do — stop, or move to the nearest valid position?
• Communication is lost. Should the reference lines hold position or retract home? On most lines the right answer is “hold position”, because production may still be running.
• A new command arrives during setup. Is the current cycle cancelled, or allowed to finish?

Commissioning sequence

1. Physical connection and addressingNetwork topology, device names and the IP plan. This stage is normally handled with the line automation team.
2. Data block matchingCheck that the variables on both sides match in order and in type. Most errors appear here.
3. Dry runRun the command/acknowledge loop with the lasers switched off.
4. Position verificationMeasure the reference line positions on the machine for a few recipes.
5. Fault scenariosTrigger the three conditions above deliberately and record the behaviour.

To discuss your line’s automation infrastructure and recipe flow, get in touch.