This page explains how to view data sent and received by Arduino Code in the Serial Monitor and how to inspect contact, coil, memory, and power-flow states with ladder monitoring.

The two features inspect different data and present different results.

Use the Serial Monitor to inspect data exchanged by Arduino Code through a board serial port. Use ladder monitoring to inspect the internal state of the ladder logic running on the board.

1. Choose the PC serial port under Select port at the right of the status bar.
2. Select Serial Monitor on the Activity Bar, or open the Serial Monitor tab in the bottom panel.
3. Select the same baud rate used by Serial.begin() in Arduino Code.
4. Select the receive encoding, then choose Connect.
5. Confirm that the state changes to Connected.

• 1 Target port: The PC serial port selected on the status bar.
• 2 Baud rate: Select the value used by Serial.begin().
• 3 Encoding: Select how received bytes are decoded as text.
• 4 Connect: Connect, disconnect, and check the reconnecting state.

The receive encodings are UTF-8, EUC-KR (Korean), Shift-JIS (Japanese), Latin-1 (ISO-8859-1), and Windows-1252. The default is UTF-8. Encoding affects received data in ASCII view only; it does not affect HEX view or transmitted data.

Changing the baud rate while connected does not update the active connection. Select Disconnect, then connect again. If the selected rate differs from Serial.begin(), text may be garbled or no data may appear.

The following code sends a counter value once per second and resets it to zero when the PC sends R or r.

unsigned long previousMillis = 0;
int count = 0;
 
void setup() {
  Serial.begin(9600);  // Set the Serial Monitor to 9600 baud as well.
  Serial.println("Counter ready. Send R to reset.");
}
 
void loop() {
  if (millis() - previousMillis >= 1000) {  // Send a value once per second.
    previousMillis = millis();
    count++;
    Serial.print("count = ");
    Serial.println(count);
  }
 
  if (Serial.available() > 0) {  // Read data received from the PC.
    char received = Serial.read();
    if (received == 'R' || received == 'r') {
      count = 0;
      Serial.println("-- reset --");
    }
  }
}

Build and upload the code, then connect the Serial Monitor at 9600 baud. count = 1, count = 2, and later values appear once per second. Enter R and press Enter or Send to see > R followed by the board response – reset –.

ASCII view decodes received bytes as text with the selected encoding. HEX view shows the same data as two-digit uppercase bytes separated by spaces, such as 41 42 0D 0A.

Switching the view clears the previous receive buffer and begins displaying data in the new mode. The button names the mode you will switch to, rather than the current mode.

Use the selector beside the input field to choose the bytes appended to transmitted data.

Text entered in ASCII view is always transmitted as UTF-8. In HEX view, enter raw bytes such as 52 or 52 0D 0A. 520D0A without spaces is also accepted. Input containing a non-hexadecimal character or an odd number of digits is not sent.

Copy copies the entire current receive buffer to the clipboard. Clear empties the displayed buffer without disconnecting.

The project sends ladder-monitoring data through the selected board communication channel. Select the channel first, then rebuild and upload the project to apply the change to the board.

1. Open Settings → Ladder Settings → Monitoring port.
2. Select the board communication channel connected to the PC.
3. Build and upload the project again.
4. Select the corresponding PC serial port on the status bar.

Only channels available on the selected board appear in the list. Selecting Off prevents the firmware from generating ladder-monitoring data. The available Serial, Serial1, and Serial2 entries follow the communication channels defined for the selected board. MPINO-8A4R(T)-S shows Off, Serial, and Serial1.

If you start monitoring after changing the channel but before uploading, an upload notice appears. Select Upload to apply the new channel to the board.

Port conflict: Monitoring data conflicts with project communication or Arduino Code that uses the same board channel. If a conflict notice appears, select a dedicated monitoring channel or change the communication settings and code using that channel.

After setting the port and uploading, start or stop ladder monitoring in any of these ways:

• The Monitoring button in the Serial Monitor header
• Monitoring ON or Monitoring OFF on the ladder context menu
• Ctrl + M

Shortcuts can be changed under File → Preferences → Keyboard Shortcuts.

If Monitoring port is Off, the Monitoring Port Required notice opens. Select Open Preferences and complete the settings in section 4.

If no PC serial port is selected, choose one on the status bar and start monitoring again. When monitoring starts, the button and context-menu state change to ON. Stopping monitoring closes the connection and removes live indications from the ladder.

While monitoring is on, the ladder shows both power flow and live cell values.

• 1 Box-function value: Inspect the live timer, counter, or calculation target inside the box.
• 2 Word value: Inspect D, C, T, and similar values below the cell.
• 3 Timer value: Inspect a timer address in time units or as a number.
• 4 Comparison values: The live operands appear below the contact, and power flow shows the comparison result.

If the board stops or the connection is lost, the last received values and power-flow indication may remain on screen. The time-driven @F special bit stops flashing in this state. When values stop changing, check the monitoring connection first.

Right-click a ladder cell to select the format used for live numeric values. A check mark identifies the selected format.

The image compares one 16-bit value. A 32-bit value uses eight digits in Hexdecimal and 32 digits in Binary. R memory is displayed from its stored 32-bit floating-point value.

The format is a global setting for all projects on this PC, rather than a setting for one cell or project. It persists after restarting the application. The default is Signed Decimal.

When a timer preset uses time syntax such as TON T0 1m10s, Signed Decimal displays the live value with time units such as 1m10s, 43s210ms, or 500ms. A numeric preset produces a numeric live value.

Selecting a format other than Signed Decimal displays the timer value in that number format instead of time syntax. Counter presets do not use time units.

During monitoring, a comparison such as D0 > D1 shows live operands such as 5 > 3 below the contact. Binary values wrap onto multiple lines; the other formats use one line.

The Serial Monitor and ladder monitoring share the one PC serial port selected on the status bar, so they cannot be connected at the same time.

The baud selected in the Serial Monitor remains unchanged while ladder monitoring connects at 115200 baud. The saved value is used when you reconnect the regular Serial Monitor.

If the board is disconnected, the regular Serial Monitor attempts to reconnect up to five times. After a successful reconnect, a reconnect notice is added to the receive buffer. If automatic attempts end without a connection, check the port list and cable, then reconnect manually. If ladder-monitoring values stop, do not wait for an automatic recovery; turn monitoring off and on again.

An upload disconnects the active owner first and restores the previous Serial Monitor or ladder-monitoring connection after the upload, whether it succeeds or fails. If neither feature was connected, both remain off. Running a build without uploading does not disconnect them.

During ladder monitoring, Serial.print() output on the same channel at 115200 baud can still appear in the Serial Monitor receive view. Because user data can mix with monitoring frames, use separate channels for Arduino Code communication and ladder monitoring whenever possible.

• Phase 1 · Create Your First Project — build, upload, and port selection
• Phase 2 · Understand Memory — memory types used by monitored values
• Phase 3 · Ladder Editing Basics — contacts, coils, and comparison contacts
• Phase 4 · Box Functions — timer and counter box functions
• Phase 5 · Editing Arduino Code — writing the serial example
• MPINO STUDIO 2 User Manual