Device PanelSampler

PanelSampler

This page is generated from the Unity twin. Published from _docs/context/devices/panelsampler.md — edit it there, not here. Changes made in the wiki are overwritten on the next sync.

Not a device: a collector. Packs up to 32 buttons and lamps into a single 32-bit word in each direction, so a whole operator panel costs the PLC one address.

Twin device type · twin FB FB_Panel · 2 instances in FG_System · Unity component OC.Interactions.PanelSampler

What it is

An operator panel has a dozen buttons and lights on it. Giving each one its own PLC address is wasteful and tedious, so the panel is sampled: every control it lists is packed, bit by bit, into one 32-bit status word going up and one 32-bit control word coming down.

What the PLC sees

One 32-bit word each way. Bit n of the status word is the n-th listed control's status bit; bit n of the control word is written back to that same control. In practice, for a panel of push buttons: the status word says which buttons are pressed, and the control word lights their lamps.

Which control sits on which bit is a property of one particular panel, so it is stated on that panel's own device — see the Bit mapping section of the group page that owns it.

How the twin models it

The panel holds an ordered list of controls. Each declares how many bits it needs — a button one, a lamp one — and they are allocated in list order from bit 0. At startup the panel switches off each listed control's own PLC link and takes it over; a sampled button is no longer a device the PLC can address by itself. It also builds the on-screen operator panel from the same list.

Watch out

• The list order is the bit assignment. Reordering the list in Unity silently moves every signal to a different bit, and a control program written against the old order keeps running and does the wrong things.
• 32 bits is the ceiling. A panel that asks for more is rejected at startup and reports nothing at all.

In this machine

There are 2 of them, in FG_System:

Device	Twin PLC path	Group	Role / Signal
H_ControlPanel †	MAIN.FG_System.H_ControlPanel	FG_System	PanelSampler. Disables its children's individual communication and exposes one aggregated FB_Panel DWORD, packing their status bits in and unpacking control bits back.
H_SignalTower	MAIN.FG_System.H_SignalTower	FG_System	PanelSampler. Aggregates the four tower lamps into one FB_Panel DWORD, with the lamps own links disabled. Same packing mechanism as the control panel.

† From the reference scene only. Every scene instances the same Machine_1 prefab, but each adds its own vendor's operator panel, so this row is VC_Demo_1_Beckhoff_1's and another scene spells it differently. The machine is what is unmarked; a marked row is an example. Each vendor's own is on its page below.

Control implementations

The twin is master for structure, and that is all this page states. Which control function block each instance becomes, its process-image members and its published HMI struct is the control platform's own knowledge base:

• Beckhoff
• Siemens — no knowledge base published yet