JaamSim Remote Control --- User Manual

What It Does

This Python script connects to your JaamSim simulation through Kafka. It lets you control the simulation and modify entities in real-time from outside JaamSim --- no need to touch the JaamSim GUI.

Your Java plugin (KafkaCommandListener) runs inside JaamSim and listens for commands on the Kafka topic jaamsim-commands. This Python script sends commands to that topic.

Requirements

• Kafka running on localhost:9092

• JaamSim running with the Java Kafka plugin loaded

• Python with kafka-python installed (pip install kafka-python)

Starting Up

python jaamsim_control.py

You'll see this menu:

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JaamSim Remote Control

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--- Toggle Buttons ---

1 = Toggle ToggleButton1

2 = Toggle ToggleButton2

--- Simulation Control ---

s = Start/Resume simulation

p = Pause simulation

x = Stop simulation

--- Entity Control ---

e = Edit any entity input

qe = Query any entity input

q = Quit

Commands

1 --- Toggle ToggleButton1 {#toggle-togglebutton1}

Flips ToggleButton1 between ON and OFF. If it's currently ON, it goes OFF, and vice versa.

Enter command: 1

-> Sent: {'entity': 'ToggleButton1', 'action': 'TOGGLE'}

Use case: ToggleButton1 might control a branch in your model --- e.g., enabling/disabling a conveyor path.

2 --- Toggle ToggleButton2 {#toggle-togglebutton2}

Same as above but for ToggleButton2.

Enter command: 2

-> Sent: {'entity': 'ToggleButton2', 'action': 'TOGGLE'}

s --- Start / Resume Simulation {#s-start-resume-simulation}

Starts the simulation if it's stopped, or resumes it if it's paused.

Enter command: s

-> Sent: {'action': 'SIM_START'}

p --- Pause Simulation {#p-pause-simulation}

Pauses the simulation. The sim time freezes but everything stays in place. Use s to resume.

Enter command: p

-> Sent: {'action': 'SIM_PAUSE'}

x --- Stop Simulation {#x-stop-simulation}

Fully stops the simulation and resets it. You'd need to press s to start from the beginning.

Enter command: x

-> Sent: {'action': 'SIM_STOP'}

e --- Edit an Entity Input {#e-edit-an-entity-input}

This is the most powerful command. It lets you change any input on any entity in the running model.

How it works:

1. You type the exact entity name (as it appears in JaamSim)

2. You type the exact input/keyword name

3. You type the new value

Example 1 --- Change a server's processing time:

Enter command: e

Entity name: Server1

Input name: ServiceTime

New value: 5 s

This changes Server1's service time to 5 seconds.

Example 2 --- Change an entity's position:

Enter command: e

Entity name: Server1

Input name: Position

New value: 1.0 2.0 0.0 m

Example 3 --- Change a generator's arrival rate:

Enter command: e

Entity name: EntityGenerator1

Input name: InterArrivalTime

New value: 10 s

Example 4 --- Change a queue's max size:

Enter command: e

Entity name: Queue1

Input name: MaxValidLength

New value: 20

Tips:

• Entity names and input names are case-sensitive --- they must match exactly what's in JaamSim

• Values must be in the same format JaamSim expects (including units like s, m, h)

• To find the exact input names, click on an entity in JaamSim and look at the Input Editor panel

qe --- Query an Entity Input {#qe-query-an-entity-input}

Sends a request to read an entity's current input value.

Enter command: qe

Entity name: Server1

Input name: ServiceTime

-> Sent: {'entity': 'Server1', 'action': 'QUERY', 'input': 'ServiceTime'}

⚠️ Important limitation: The response is sent back on the jaamsim-events Kafka topic, but this script does not listen to that topic. So you won't see the answer in this script. The result will appear in JaamSim's console/log output instead.

q --- Quit {#q-quit}

Closes the Kafka connection and exits the script.

Enter command: q

Bye!

Typical Workflow

1. Open JaamSim with your model and the Kafka plugin loaded

2. Start Kafka (zookeeper + kafka-server-start)

3. Run the Python script

4. Press s to start the simulation

5. Press 1 or 2 to toggle buttons as needed

6. Use e to tweak parameters while the sim runs

7. Press p to pause and inspect, s to resume

8. Press x to stop and reset

9. Press q to exit

Troubleshooting

Problem	Solution
NoBrokersAvailable	Kafka isn't running --- start Zookeeper and Kafka first
Command sent but nothing happens in JaamSim	Make sure the Java plugin is loaded and listening on jaamsim-commands
e command doesn't change anything	Double-check entity name and input name --- they're case-sensitive
Unknown entity error in JaamSim logs	The entity name you typed doesn't exist in the model