Sink blocks (Scope, Display, To Workspace) in Simulink

Introduction

Sink blocks help you see or save the results of your Simulink model. They show outputs or save data for later use.

You want to watch how signals change during simulation.

You need to save simulation data to analyze it outside Simulink.

You want a quick visual check of signal values while the model runs.

You want to export data to MATLAB workspace for plotting or calculations.

You want to monitor multiple signals at once in one place.

Syntax

Simulink

Scope
Display
To Workspace

Scope shows signals as graphs during simulation.

Display shows numeric values updating live.

To Workspace saves data to MATLAB workspace after simulation.

Examples

Scope lets you watch signal changes over time visually.

Simulink

Add a Scope block and connect it to a signal line.
Run simulation to see the signal graph.

Display shows the numeric value of the signal during simulation.

Simulink

Add a Display block connected to a signal.
Run simulation to see the current value update.

To Workspace saves signal data for later analysis or plotting.

Simulink

Add a To Workspace block connected to a signal.
Set variable name and format.
Run simulation.
Check saved data in MATLAB workspace.

Sample Program

This code creates a simple Simulink model with a Sine Wave source. It sends the signal to a Scope for live viewing and to a To Workspace block to save data. After simulation, it shows the first 5 rows of saved data in MATLAB workspace.

Simulink

% Create a simple Simulink model programmatically
model = 'simple_model';
new_system(model);
open_system(model);

% Add Sine Wave block
add_block('simulink/Sources/Sine Wave', [model '/Sine Wave']);
set_param([model '/Sine Wave'], 'Frequency', '1');

% Add Scope block
add_block('simulink/Sinks/Scope', [model '/Scope']);

% Connect Sine Wave to Scope
add_line(model, 'Sine Wave/1', 'Scope/1');

% Add To Workspace block
add_block('simulink/Sinks/To Workspace', [model '/To Workspace']);
set_param([model '/To Workspace'], 'VariableName', 'simData');

% Connect Sine Wave to To Workspace
add_line(model, 'Sine Wave/1', 'To Workspace/1');

% Run simulation
sim(model);

% Display saved data
simData(1:5,:)

Important Notes

Scope is good for visual checks but does not save data after simulation ends.

Display shows only current values, not history.

To Workspace saves data in different formats: array, structure, or timeseries.

Summary

Sink blocks let you view or save simulation outputs.

Use Scope for graphs, Display for live numbers, and To Workspace to save data.

They help analyze and understand your Simulink model results.

Practice

1. Which Simulink sink block is best for showing a live numeric value during simulation?

easy

A. Display block

B. Scope block

C. To Workspace block

D. Gain block

Solution

1. Step 1: Understand the purpose of Display block

   The Display block shows numeric values updating live during simulation.

2. Step 2: Compare with other sink blocks

   Scope shows graphs, To Workspace saves data, Gain modifies signals, so they don't show live numbers directly.

3. Final Answer:

   Display block -> Option A

4. Quick Check:

   Live numeric value = Display block [OK]

Hint: Display shows live numbers; Scope shows graphs [OK]

Common Mistakes:

• Confusing Scope with Display
• Thinking To Workspace shows live values
• Selecting Gain which is not a sink block

2. Which of the following is the correct way to configure a To Workspace block to save data as a structure?

easy

A. Set 'Save format' to 'Array'

B. Set 'Save format' to 'Timeseries'

C. Set 'Save format' to 'Structure with time'

D. Set 'Save format' to 'Matrix'

Solution

1. Step 1: Identify the save format options in To Workspace block

   To Workspace block allows saving data as Array, Structure with time, Timeseries, or Matrix.

2. Step 2: Choose the option that saves data as a structure

   'Structure with time' saves data as a structure containing time and signals.

3. Final Answer:

   Set 'Save format' to 'Structure with time' -> Option C

4. Quick Check:

   Structure save format = 'Structure with time' [OK]

Hint: Structure format is named 'Structure with time' in To Workspace [OK]

Common Mistakes:

• Choosing 'Array' which saves plain arrays
• Confusing 'Timeseries' with structure
• Selecting 'Matrix' which is not a valid option

3. Given this Simulink model snippet:

Signal -> To Workspace block (Save format: Array)

After simulation, what is the format of the saved data in MATLAB workspace?

medium

A. A numeric array containing signal values only

B. A structure with time and signals fields

C. A timeseries object with time and data

D. A cell array with signal data

Solution

1. Step 1: Understand 'Array' save format in To Workspace block

   When 'Array' is selected, only the signal values are saved as a numeric array without time info.

2. Step 2: Compare with other formats

   Structure and Timeseries formats include time; cell arrays are not used here.

3. Final Answer:

   A numeric array containing signal values only -> Option A

4. Quick Check:

   Save format 'Array' = numeric array [OK]

Hint: Array format saves only values, no time info [OK]

Common Mistakes:

• Assuming time is saved with Array format
• Confusing Array with Timeseries
• Expecting a structure instead of array

4. You added a Scope block but see no graph during simulation. What is the most likely cause?

medium

A. The simulation time is zero

B. The Display block is missing

C. The To Workspace block is set to 'Array' format

D. The Scope block is not connected to any signal

Solution

1. Step 1: Check Scope block connection

   Scope requires a connected signal to display data; no connection means no graph.

2. Step 2: Evaluate other options

   Display block absence doesn't affect Scope; To Workspace format doesn't affect Scope display; simulation time zero means no data but usually simulation runs longer.

3. Final Answer:

   The Scope block is not connected to any signal -> Option D

4. Quick Check:

   Scope needs signal connection [OK]

Hint: Scope shows graphs only if connected to signals [OK]

Common Mistakes:

• Thinking Display block affects Scope
• Confusing To Workspace settings with Scope display
• Ignoring signal connections

5. You want to analyze simulation data after running a model. Which sink block should you use to save the data for MATLAB post-processing, and how should you configure it to include time information?

hard

A. Use Scope block; enable data logging

B. Use To Workspace block; set 'Save format' to 'Structure with time'

C. Use Display block; no configuration needed

D. Use To Workspace block; set 'Save format' to 'Array'

Solution

1. Step 1: Identify the sink block for saving data

   To Workspace block is designed to save simulation data to MATLAB workspace for post-processing.

2. Step 2: Choose the save format to include time

   Setting 'Save format' to 'Structure with time' saves both signal data and time stamps.

3. Final Answer:

   Use To Workspace block; set 'Save format' to 'Structure with time' -> Option B

4. Quick Check:

   Save data with time = To Workspace + 'Structure with time' [OK]

Hint: To save with time, use To Workspace + 'Structure with time' [OK]

Common Mistakes:

• Using Display or Scope blocks to save data
• Choosing 'Array' format which lacks time info
• Not configuring save format properly