This page explains how to create and manage Arduino Code files, write code, use completion and Go to Definition, find and replace text, and locate code errors.

Select a file under Code in Explorer to open it in the Arduino Code editor. The markers correspond to the descriptions below.

• 1 Code group: Lists the Arduino Code files in the project.
• 2 Line numbers and folding: Shows code locations and folds or expands functions and blocks.
• 3 Editing area: Used to write and edit Arduino C/C++ code.
• 4 Minimap: Shows the file structure and the currently visible area.

Selecting a file displays its contents and updates the selected item in Explorer.

The first code file in a new project is named main. When the project is saved for the first time, its name changes automatically to match the project file name.

The first code file is the project entry file. It stays at the top of the Code list and cannot be renamed, deleted, or moved directly.

Do not type the extension in a code file name. A name cannot be empty, start with a period, contain /ㆍ\ㆍ.., or differ from an existing name only by letter case.

Moving an additional file updates the current working list. When the project is opened again, additional files are sorted by name.

Separating code by function makes a project easier to navigate and maintain. In this example, a function that limits a value is written in control and called from the primary code file.

int limitValue(int value) {
  return constrain(value, 0, 100);  // Limit the value to the range 0 to 100.
}

void setup() {
}
 
void loop() {
  D0 = limitValue(D1);  // Limit D1 to 0 through 100 and store it in D0.
  ladderLoop();         // Run the ladder logic.
}

• limitValue() uses the Arduino function constrain() to return its argument within the range 0 through 100.
• Multiple .ino files in one project are built together as one sketch, so a function in one file can be called from another.
• This example was compiled successfully in an MPINO-8A4R(T)-S project.

For the storage types of D0 and D1 and sharing PLC memory with Arduino Code, see Phase 2 · Understand Memory. To call an Arduino function from a ladder box function, see Calling an Arduino Code Function.

Caution: If ladderLoop() is removed from loop(), the ladder logic will not run.

As you type the beginning of a function or variable name, available items appear in the completion list.

1. Type the beginning of a function or variable name in the code editor.
2. If the list does not open, press Ctrl + Space.
3. Select an item with ↑ or ↓.
4. Insert the selected item with Enter or Tab.

In the preceding example, typing limitV lets you select limitValue() from the other code file.

Board-core and library items may appear after code analysis finishes. A completed name still needs the argument count and types required by its definition.

Place the cursor on a function or variable name and press F12 to open its definition.

Pressing F12 on limitValue() in the primary code file opens its definition in control. Arduino-core functions such as constrain() open in a read-only definition view. Close that view with its close button or Esc.

• 1 Call site: The function whose definition you want to inspect.
• 2 Function definition: The declaration or implementation opened by F12.
• 3 Read-only: Arduino-core and library definitions cannot be edited here.

The same shortcut performs a different action according to the focused editor.

Arduino Code and Ladder Logic use a find-and-replace interface suited to the active editor.

Match Case, Match Whole Word, and Regular Expression options are available.

Focus the ladder grid and press Ctrl + F. Search the current ladder or all ladders for contact and coil addresses and code text in cells.

When a new error or warning is added, you can inspect its message and location in the bottom Problems panel. If the panel is hidden, press Ctrl + J and select Problems.

1. Read the badge on the Problems tab for the combined error and warning count.
2. Read the severity and diagnostic message.
3. Check the displayed file name and line and column numbers.
4. Selecting a problem in the primary code file moves to that code location.

• 1 Problems and count: The combined number of errors and warnings.
• 2 Error message: The diagnostic text used to identify the cause.
• 3 File, line, and column: The location where the problem was found.
• 4 Code location: The line opened by selecting the problem.

For an error in an additional code file, read its file name and line number in Problems, then open that file directly from Explorer.

For the full build output and rebuilding a project, see Phase 1 · Create Your First Project.

Shortcuts can be changed under File → Preferences → Shortcuts.

F2, F12, Delete, and Ctrl + ↑ or Ctrl + ↓ can perform other actions when focus is elsewhere. Select the code area or file in Explorer before using them.

• Phase 1 · Create Your First Project — Build, upload, and build output
• Phase 2 · Understand Memory — Share PLC memory with Arduino Code
• Phase 3 · Ladder Editing Basics — Edit ladder cells, contacts, and coils
• Phase 4 · Box Functions — Box functions and Arduino function calls
• MPINO STUDIO 2 User Manual