Sink blocks (Scope, Display, To Workspace) in Simulink - Step-by-Step Execution

Concept Flow - Sink blocks (Scope, Display, To Workspace)

Simulink Model Runs

↓

Signal Generated

↓

Signal Sent to Sink Block

↓

Scope: Visualize Signal

↓

Display: Show Numeric Value

↓

To Workspace: Save Data

↓

End of Simulation

The model runs and generates signals that are sent to sink blocks. Each sink block handles the signal differently: Scope shows a graph, Display shows a number, and To Workspace saves data for later use.

Execution Sample

Simulink

signal = sin(t);
scope(signal);
display(signal);
to_workspace(signal);

Simulink sends a sine wave signal to Scope, Display, and To Workspace blocks to visualize, show, and save the data.

Execution Table

Step	Signal Value (t)	Scope Output	Display Output	To Workspace Output	Action
1	0.0	Plot point at 0.0	0.0	[0.0]	Signal generated and sent to sinks
2	0.5	Plot point at 0.479	0.479	[0.0, 0.479]	Signal updated and sinks updated
3	1.0	Plot point at 0.841	0.841	[0.0, 0.479, 0.841]	Signal updated and sinks updated
4	1.5	Plot point at 0.997	0.997	[0.0, 0.479, 0.841, 0.997]	Signal updated and sinks updated
5	2.0	Plot point at 0.909	0.909	[0.0, 0.479, 0.841, 0.997, 0.909]	Signal updated and sinks updated
6	2.5	Plot point at 0.598	0.598	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598]	Signal updated and sinks updated
7	3.0	Plot point at 0.141	0.141	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598, 0.141]	Signal updated and sinks updated
8	3.5	Plot point at -0.350	-0.350	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598, 0.141, -0.350]	Signal updated and sinks updated
9	4.0	Plot point at -0.757	-0.757	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598, 0.141, -0.350, -0.757]	Signal updated and sinks updated
10	4.5	Plot point at -0.977	-0.977	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598, 0.141, -0.350, -0.757, -0.977]	Signal updated and sinks updated
11	5.0	Plot point at -0.959	-0.959	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598, 0.141, -0.350, -0.757, -0.977, -0.959]	Simulation ends

💡 Simulation ends after final time step; all sink blocks have received and processed the signal.

Variable Tracker

Variable	Start	After 1	After 2	After 3	After 4	After 5	After 6	After 7	After 8	After 9	After 10	Final
signal(t)	0.0	0.479	0.841	0.997	0.909	0.598	0.141	-0.350	-0.757	-0.977	-0.959	-0.959
Scope Output	Plot point at 0.0	Plot point at 0.479	Plot point at 0.841	Plot point at 0.997	Plot point at 0.909	Plot point at 0.598	Plot point at 0.141	Plot point at -0.350	Plot point at -0.757	Plot point at -0.977	Plot point at -0.959	Plot point at -0.959
Display Output	0.0	0.479	0.841	0.997	0.909	0.598	0.141	-0.350	-0.757	-0.977	-0.959	-0.959
To Workspace Output	[0.0]	[0.0, 0.479]	[0.0, 0.479, 0.841]	[0.0, 0.479, 0.841, 0.997]	[0.0, 0.479, 0.841, 0.997, 0.909]	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598]	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598, 0.141]	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598, 0.141, -0.350]	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598, 0.141, -0.350, -0.757]	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598, 0.141, -0.350, -0.757, -0.977]	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598, 0.141, -0.350, -0.757, -0.977, -0.959]	[0.0, 0.479, 0.841, 0.997, 0.909, 0.598, 0.141, -0.350, -0.757, -0.977, -0.959, -0.959]

Key Moments - 3 Insights

Why does the Display block only show one number at a time, while the To Workspace block saves many?

The Display block shows the current signal value at each step (see execution_table Display Output column), while the To Workspace block collects all values over time into an array (see To Workspace Output column).

How does the Scope block show the signal over time?

The Scope block plots each signal value as a point on a graph at each time step (execution_table Scope Output). It accumulates points to show the signal's shape over time.

What happens if the simulation stops before the final time?

The sink blocks will only have data up to the last simulation step (see exit_note). The To Workspace block will save fewer points, and Scope and Display will show data only up to that point.

Visual Quiz - 3 Questions

Look at the execution table at Step 5. What is the Display Output value?

A 0.997

B 0.909

C 0.598

D 0.841

💡 Hint

Check the Display Output column at Step 5 in the execution_table.

At which step does the To Workspace Output first contain 5 values?

A Step 3

B Step 7

C Step 5

D Step 10

💡 Hint

Look at the length of the array in To Workspace Output column in execution_table.

If the simulation ended at Step 6, what would be the last value in the Scope Output?

A Plot point at 0.598

B Plot point at 0.141

C Plot point at 0.909

D Plot point at 0.997

💡 Hint

Check Scope Output at Step 6 in the execution_table.

Concept Snapshot

Sink blocks receive signals in Simulink models.
Scope shows signal as a graph over time.
Display shows the current numeric value.
To Workspace saves all signal values for later use.
They help visualize and save simulation data easily.

Full Transcript

In Simulink, sink blocks like Scope, Display, and To Workspace receive signals from the model. The Scope block plots the signal over time, showing how it changes. The Display block shows the current value of the signal at each simulation step. The To Workspace block saves all the signal values into an array for later analysis. During simulation, the signal updates at each time step, and all sink blocks update accordingly. When the simulation ends, the data collected by these blocks can be viewed or used for further processing.

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