10. Instructor and Operator on Separate PCs

On a single PC the instructor and the trainee share a screen and a mouse. A training rig puts them apart: the instructor's DWSIM runs the plant, and one or more operator stations, each a DWSIM of its own on any PC of the network, mirror the session and send the trainee's actions back.

What you will learn

• Publishing the session to stations
• Launching a station on the same PC, and connecting one from another PC
• What a station mirrors and what it can do
• Requirements and limits

Prerequisites

• Page 5 and page 6
• The flowsheet saved to a file both PCs can open

How it works

sequenceDiagram
    participant I as Instructor's DWSIM
    participant S as Operator station (another DWSIM)
    S->>I: hello (station name, object list)
    I->>S: welcome (screens, interlock logic)
    loop every step (throttled) and once a second
        I->>S: frame: plant state, time, alarms, interlocks, journal lines
    end
    S->>I: command: set point, valve, ack, reset...
    I->>I: applied as an operator action, journaled with the station's name

The station opens the same flowsheet file and keeps a local copy of the plant in step with the instructor's: every frame carries the whole process state, compressed, and the station loads it into its own objects. Its operator panel, screens, faceplates, alarm summary, interlocks and trends then work exactly as on the instructor's PC, reading local objects. The station's clock, however, belongs to the instructor: Start, Freeze and Stop are refused there.

Everything the trainee does on a station travels back as a command and is applied by the instructor's session, so the journal reads PID-012 set point -> 2.5 bar [Station 1 @ ROOM-B].

Publishing the session

Stations... on the Instructor Station.

1. Port 4850 (or any free one), Start. The window lists the addresses stations can connect to (every IPv4 address of the PC).
2. The grid shows each connected station: name, address, connected at, frames sent, commands received.
3. Launch an operator station on this PC starts a second DWSIM with the same file, told to connect back automatically. Use it to give the trainee a second monitor with a window of their own, or to try the setup before the second PC arrives. The flowsheet must be saved first: the station opens the file.

The server keeps running when the window closes; Stop disconnects everyone.

Connecting from another PC

On the trainee's PC:

1. Open the same .dwxmz (a shared folder, or a copy: the objects must be the same, screens and interlocks come from the instructor).
2. Operator Training > Operator Station (Remote).
3. Instructor PC: the address shown in the instructor's Stations window; Port 4850; Station name: what the journal will show for this trainee.
4. Connect. The operator panel opens, and the screens if the file has any. The window stays as a link monitor (frames received, last frame age, apply time) with Disconnect and Operator windows to reopen them.

If the file on the station lacks objects the instructor has, the connection is refused with the missing tags listed: open the instructor's current file.

What a station can and cannot do

Works on a station	Stays with the instructor
Operator panel, faceplates, screens, alarm summary, interlock status	Start, Freeze, Step, Stop, speed
Set points, manual outputs, valve openings, switches, duties, pump start and stop, screen buttons	Malfunctions, scenarios, snapshots, backtrack
Acknowledge alarms; reset and bypass interlocks	Force reset of interlocks
Trends (sampled from the frames it receives)	Screens designer, interlock configuration
	OPC UA server, this window

Requirements and limits

• Both DWSIMs need the Patreon level 3 subscription active.
• One TCP port open from the station to the instructor's PC (4850 by default). Nothing else is needed: no shared database, no admin rights.
• Frames are throttled so serialising the plant costs the instructor at most a fifth of the step time; on a small plant that is a few milliseconds and four frames a second. A slow station always gets the newest frame; older ones are dropped.
• A station shows the plant with a delay of one frame; commands are applied at the instructor's next step.
• If the link drops, the station's clock shows the last state and the link window reports the reason; Connect again once the instructor is back.

The next page covers the pressure-flow network solver, which runs on the instructor's side.