Moxa NPorts FAQ | Easy World Automation

Serial-to-Ethernet connectivity allows traditional RS-232/422/485 devices to communicate over Ethernet networks. A Moxa NPort serial-to-Ethernet device server converts serial data into TCP/IP packets for integration. This enables legacy industrial equipment to connect to modern Ethernet-based systems without requiring changes to existing software.

1. Virtual COM ports allow PCs and applications to access serial devices as if they were directly connected.

2. Industrial device servers support TCP, UDP, and other network protocols for flexible communication.

3. Web-based configuration and management simplify the setup and monitoring of multiple devices.

4. Centralized tools like MXview help manage, monitor, and troubleshoot serial devices across networks.

This solution is widely used in industrial automation, SCADA, IoT, and remote monitoring applications.

The Moxa NPort works as a serial to Ethernet device server by converting RS-232/422/485 signals into TCP/IP packets and allows serial devices to communicate over Ethernet networks. This integration makes the NPort device server ideal for industrial automation, remote monitoring, and centralized control. The device, with its reliable protocol support, ensures stable and secure data transmission between legacy equipment and modern IP-based systems.

You can connect serial devices to an Ethernet network by using a serial device server like a Moxa NPort. First, connect the serial device to the server’s RS-232/422/485 port, then connect the server to your Ethernet network. Assign an IP address and configure the server via its web GUI or software.

Optionally, install virtual COM port drivers on your PC so the serial device behaves like a local COM port. Tools like MXview can help monitor and manage multiple devices across the network.

The default IP address and login for Moxa NPort devices are:

IP Address: Your specific IP

Subnet Mask: Your subnet mask is used in IP

Username: admin

Password: moxa

Tip: After the first login, it’s highly recommended to change the IP and password to match your network and security requirements.

1. Device Not Found on Network

Cause: IP mismatch, subnet issue, or disconnected cable.

Solution: Check Ethernet cables and LEDs.

Use NPort Administrator to scan the network.

Ensure PC and NPort are in the same subnet.

Reset to factory default if necessary.

2. Serial Data Not Transmitting

Cause: Serial settings mismatch or wrong operation mode.

Solution: Verify baud rate, parity, data bits, and stop bits match the serial device.

Check if the NPort is in the correct mode (Real COM, TCP Server/Client, UDP).

Test with a terminal program (PuTTY, RealTerm).

3. Connection Drops or Unstable

Cause: Network instability or firewall blocking traffic.

Solution: Ensure a stable Ethernet connection and switch port settings.

Adjust session timeout in NPort settings.

Check firewall and antivirus rules.

Update firmware if needed.

4. Virtual COM Ports Not Working (Real COM Mode)

Cause: Driver issue or port conflict.

Solution: Reinstall the Moxa Virtual COM driver.

Assign a different COM port number.

Restart the PC and try again.

5. Cannot Access Web Console

Cause: Wrong IP, browser issue, or firewall block.

Solution: Ping the NPort IP to confirm connectivity.

Use a different browser.

Temporarily disable the firewall/antivirus.

If still inaccessible, factory reset the device.

6. Firmware / Device Malfunction

Cause: Corrupted firmware or hardware issue.

Solution: Check the LED status per the user manual for error codes.

Update firmware using NPort Administrator or web console.

Contact Moxa support if hardware repair/replacement is needed.

Tip: Always keep a backup of your NPort configuration before changes. Use NPort Administrator or MXconfig for exporting settings.

step-by-step guide to reset a Moxa NPort:

Method 1: Using the Reset Button (Hardware Reset)

Ensure the NPort is powered on.

Locate the Reset button (small pinhole or button on the device).

Press and hold the Reset button for about 5–10 seconds until the Ready / SYS LED blinks.

Release the button and wait for the device to reboot.

The NPort will restore factory default settings, including IP, username, password, and serial configurations.

Method 2: Using the Web Console

Log in to the NPort web interface via browser (http://<NPort-IP>).

Navigate to Maintenance → Restore Defaults (or similar menu).

Select Factory Default and confirm.

Wait for the NPort to reboot with default settings.

Method 3: Using NPort Administrator

Open NPort Administrator on your PC.

Find and select your NPort device.

Right-click → Factory Default or choose from the menu.

Confirm and wait for the device to reboot.

A serial device server is a network device that allows traditional serial devices, like RS-232, RS-422, or RS-485 equipment, to connect to an Ethernet network. It converts serial data into TCP/IP packets, enabling devices such as PLCs, sensors, meters, or industrial controllers to communicate over a network.

Key points about serial device servers:

1. They provide virtual COM ports to communicate existing software with the serial device without modification.

2. Many offer web-based configuration and support for protocols like TCP, UDP, and Modbus TCP.

3. They are widely used in industrial automation, SCADA systems, IoT, and remote monitoring to modernize legacy serial devices.

In short, a serial device server bridges the gap between old serial hardware and modern Ethernet networks.

The number of hosts that can connect to a Moxa NPort serial port depends on the operation mode and the specific NPort model:

1. TCP Server Mode: Most NPort models support 4–16 simultaneous TCP client connections per serial port. Check the model datasheet for the exact maximum.

2. TCP Client Mode: Only one TCP server can be connected per serial port at a time.

3. UDP Mode: Multiple hosts can receive data simultaneously using broadcast or multicast, with no strict connection limit (network bandwidth permitting).

For distributing serial data to many hosts efficiently, UDP mode is preferred, and TCP Server mode is better for reliable and connection-oriented communication.

Yes, a Moxa NPort can send data from a serial device to multiple hosts over Ethernet, but it depends on the operation mode:

1. UDP Mode: Supports broadcast or multicast and allows the same serial data to be sent to multiple hosts simultaneously for real-time monitoring or data distribution in industrial networks.

2. TCP Server Mode: Allows multiple TCP clients to connect to the NPort (depending on the model, usually 4–16 clients). Each client receives the same serial data, enabling centralized data collection or remote monitoring.

3. TCP Client Mode: NPort initiates a connection to only one remote server at a time, so multiple hosts require multiple NPort devices or a network hub/router solution.

Use UDP mode if your goal is to efficiently distribute serial data to many hosts without establishing multiple TCP sessions.

Yes, you can monitor data passing through a Moxa NPort using several methods:

1. NPort Administrator / Web Console: Provides basic status and port activity monitoring. Shows which ports are active, connection status, and error counts.

2. Serial Sniffer / Logging Tools: In Real COM mode, you can use standard serial monitoring software (like PortMon or RealTerm) on the virtual COM port to capture and analyze data.

3. TCP/UDP Mode Monitoring: Use network tools like Wireshark to capture packets between the NPort and connected clients. Ideal for debugging TCP Server/Client or UDP communications.

5. Moxa MXconfig / MXview: Some Moxa software allows advanced diagnostics, logging, and historical data analysis for connected NPort devices.

Moxa NPort device servers are widely used across industries that require reliable serial-to-Ethernet communication, including:

Industrial Automation: Connecting legacy PLCs, sensors, and HMIs to modern SCADA and MES systems.

Energy and Utilities: Remote monitoring of power meters, substations, and renewable energy equipment.

Transportation: Railway signaling, traffic control systems, and fleet management.

Oil and Gas: Supervisory control and monitoring of pipelines, valves, and pumps.

Building Automation: Integrating HVAC, security, and lighting systems over IP networks.

Healthcare and Laboratory: Linking medical and lab instruments to centralized management systems.

The serial to Ethernet device server capability of NPort allows these industries to modernize legacy equipment, enable remote monitoring, and integrate with IP-based networks without replacing existing serial devices.

Yes, Moxa NPort supports multiple serial interfaces depending on the model:

RS-232: Standard point-to-point serial communication, used for PCs and legacy devices.

RS-422: Differential signaling for longer distances and higher speeds for multi-drop configurations.

RS-485: Differential bus communication for multi-device networks, widely used in industrial automation and Modbus applications.

Always check the specific NPort model datasheet to confirm which serial interfaces are supported. Some models support only RS-232, and others support RS-422/485 with automatic or switchable mode.

Step-by-step guide to set up a Moxa NPort for the first time:

Step 1: Unbox and Connect:

Mount the NPort on a DIN rail or place it on a stable surface. Connect the serial device (RS-232/422/485) to the NPort’s serial port. Connect the Ethernet cable to your network or directly to a PC. Power on the NPort using the supplied power adapter or terminal block.

Step 2: Discover the Device

Option A: Using NPort Administrator (Windows). Install and open NPort Administrator. Click Search Device to locate the NPort on the network.

Option B: Using a Web Browser. Connect a PC to the same subnet and open a browser. Enter the default IP (usually 192.168.127.254) to access the web console.

Step 3: Configure Network Settings

Assign a static IP address, subnet mask, and gateway suitable for your network. Apply and save the settings. The device may reboot.

Step 4: Set Serial Port Parameters

Match the baud rate, parity, data bits, and stop bits with your serial device.

Choose the desired operation mode:

Real COM (for virtual COM ports)

TCP Server / TCP Client

UDP

Step 5: Enable Security (Optional but Recommended)

Set a password for the admin account via the web console or NPort Administrator.

Step 6: Test the Connection

Use a terminal program or your serial application to send and receive data, and verify that the NPort properly relays data between the serial device and Ethernet network.

For initial setup, using NPort Administrator + Real COM mode is the easiest approach, especially if you’re connecting legacy software that expects a COM port.

Step-by-step guide to change the IP address of a Moxa NPort:

Step 1: Access the Device

Option A: Using NPort Administrator (Windows), Open NPort Administrator and click Search Device to find your NPort on the network. Select your NPort from the list.

Option B: Using a Web Browser. Open a browser and enter the current IP of the NPort (e.g., http://<NPort-IP>). Log in with your username and password.

Step 2: Open Network Settings

Navigate to Network / TCP/IP Settings in the configuration menu.

Step 3: Assign a New IP

Choose Static IP (or DHCP if your network uses it). Enter the new IP address, subnet mask, and gateway. Double-check the values to avoid IP conflicts.

Step 4: Apply and Save

Click Apply or Save. The NPort may reboot to apply the new IP settings.

Step 5: Verify

After reboot, ping the new IP from your PC (ping <new-IP>). Use NPort Administrator or the web console to confirm connectivity.

If the NPort is not reachable after changing IP, you may need to set your PC to the same subnet temporarily to reconnect and verify settings.

Step-by-step guide to configure a Moxa NPort in TCP Server mode:

Step 1: Access the NPort: Connect your PC to the same network as the NPort. Open a web browser and enter the NPort’s IP (e.g., http://<NPort-IP>), or use NPort Administrator. Log in with your credentials.

Step 2: Navigate to Operation Mode: In the configuration menu, go to Serial Settings / Operation Mode. Select TCP Server as the mode for the desired serial port.

Step 3: Configure TCP Server Parameters: Port number – set the TCP port clients will connect to (default is often 4001). Maximum connections – define how many TCP clients can connect simultaneously. Serial settings – set baud rate, parity, data bits, and stop bits to match your serial device.

Step 4: Apply and Save: Click Apply / Save to confirm settings. The NPort will reboot if required.

Step 5: Test the Connection: On a remote client (SCADA, PLC, terminal program), connect to the NPort’s IP and TCP port. Send/receive data to verify that serial-to-Ethernet communication is working properly.

TCP Server mode is ideal when the NPort device should wait for multiple clients to initiate connections, rather than actively connecting to a server.

Step 1: Install the Virtual COM Driver

Download the Moxa NPort Windows Driver from the Moxa website. Install it on your PC following the installer prompts. This driver allows your PC to create virtual COM ports mapped to the NPort serial ports.

Step 2: Discover the NPort Device

Open NPort Administrator. Click Search Device to find the NPort on your network. Make note of the IP address of the NPort device.

Step 3: Configure Serial Port Settings

Select the NPort device in NPort Administrator and click Configure. Under Serial Settings, set the baud rate, parity, data bits, and stop bits to match your serial device.

Step 4: Enable Real COM Mode

In the configuration window, select Real COM / COM Port Mode. Assign a virtual COM port number (e.g., COM3, COM4). Apply the settings.

Step 5: Test the Connection

Open your serial application (e.g., SCADA, terminal software). Select the assigned virtual COM port. Send/receive data to ensure communication between the PC and the serial device over Ethernet.

NPort Administrator:

A Windows-based utility to discover NPort devices on the network. Allows configuration of IP addresses, serial port settings, and operation modes (TCP/UDP, Real COM). Useful for batch configuration and firmware updates.

MXconfig:

A cross-platform tool for more advanced configuration and monitoring. Supports mapping of serial ports, setting security options, and device diagnostics.

Web Console:

Access via a browser using the NPort’s IP address. Provides basic setup, status monitoring, and password management without installing software. Virtual COM Driver – (optional, for Real COM mode).

Installs virtual COM ports on your PC to let legacy software communicate with NPort devices over Ethernet as if they were physical serial ports.

Yes, you can access a Moxa NPort through a web browser. Its models come with a built-in web console, allowing you to:

Log in using the device’s IP address (e.g., http://<NPort-IP>).

View device status and connected serial ports.

Configure network settings such as IP address, subnet mask, and gateway.

Set serial port parameters like baud rate, parity, and stop bits.

Enable security features, including password protection.

Choose operation modes such as Real COM, TCP Server/Client, or UDP.

The Moxa NPort is a reliable serial to Ethernet device server that allows legacy serial devices to connect to modern IP-based networks. The NPort devices, by converting RS-232/422/485 signals into Ethernet, ensure efficient data communication across industrial and commercial applications. This makes it an essential solution for integrating serial equipment into today’s smart and connected infrastructures.

Yes, you can use a Moxa NPort behind a firewall or NAT, but there are some considerations:

1. TCP/UDP Modes: The NPort initiates the connection to a remote server, so NAT/firewall traversal is usually straightforward. For TCP Server or UDP modes, you may need to forward the appropriate ports on the firewall or router to the NPort’s local IP.

2. Static IP / Port Forwarding: Assign a static IP to the NPort and configure port forwarding if external devices need to reach it.

3. Firewall Rules: Ensure the firewall allows traffic on the configured TCP/UDP ports for the NPort device server.

4. VPN Option: For secure remote access, using a VPN to bring the NPort into the same network can simplify NAT/firewall issues and improve security.

This setup ensures your serial to Ethernet device server works reliably even across segmented or protected networks.

1. Windows

Option A: Real COM Mode (Recommended for legacy apps)

Install Moxa NPort Windows Driver (Virtual COM port driver).

Open NPort Administrator, discover your NPort device on the network.

Assign a virtual COM port to the NPort serial port.

Open your serial application (SCADA, terminal software, or PLC tool) and select the assigned COM port. Data is transmitted over Ethernet transparently.

Option B: TCP/UDP Mode (Direct IP communication)

Configure NPort in TCP Client, TCP Server, or UDP mode using NPort Administrator or web console.

Use a terminal program like PuTTY or RealTerm to connect to the NPort’s IP and port.

Send/receive data directly over the network without virtual COM ports.

2. Linux

Option A: TCP/UDP Socket Communication

Configure the NPort in TCP/UDP mode via web console or configuration file.

Use Linux commands or programs (e.g., telnet <IP> <PORT>, netcat, or Python socket scripts) to communicate with the serial device.

Option B: Real COM Mode (via Moxa NPort Linux Driver)

Install Moxa’s Linux Virtual COM driver (if available for your distribution).

Assign virtual serial ports to the NPort device.

Use your serial application or scripts to communicate as if it were a local COM/TTY port.

Always check IP/subnet settings and firewall rules. For remote or VM systems, Real COM mode works best for software that expects a physical serial port.

Yes, Moxa NPort is compatible with virtual machines like VMware and Hyper-V when using Real COM mode. By installing the NPort Virtual COM driver inside the VM, the virtual machine can treat the NPort’s virtual COM ports as if they were physical serial ports. This allows legacy serial applications running on VMs to communicate with remote serial devices over Ethernet for modernized industrial setups and testing environments.

In a Moxa NPort, Real COM mode is a configuration for the serial to Ethernet device server to create virtual COM ports on a PC. These virtual ports behave exactly like physical serial ports, so existing software can communicate with remote serial devices over Ethernet without any modification. Real COM mode is widely used in industrial automation and legacy applications where software expects a standard COM interface for data exchange.

In a Moxa NPort, TCP Server mode is a setting for the serial to Ethernet device server where the NPort waits for incoming connections from TCP clients rather than initiating the connection itself.

In this mode, remote devices or applications (like SCADA systems or PLCs) can connect to the NPort to exchange serial data over Ethernet. TCP Server mode ensures reliable and connection-oriented communication for scenarios where multiple clients need to access the same serial device.

In a Moxa NPort, TCP Client mode is a communication setting for the serial to Ethernet device server where the NPort actively initiates a connection to a remote TCP server. In this mode, the device sends serial data over Ethernet only when the target server is available and ensures reliable delivery. It’s ideal for industrial applications where the central system (like a SCADA or PLC) acts as a server and multiple NPort devices send data to it over a stable TCP connection.

In a Moxa NPort, UDP mode refers to the User Datagram Protocol communication mode for the serial to Ethernet device server. Unlike TCP, UDP is connectionless, meaning data packets are sent without establishing a dedicated session between devices. This allows faster transmission with lower latency, for applications like real-time monitoring or broadcast messaging, but it doesn’t guarantee delivery or order of packets. NPort’s UDP mode is commonly used when speed is more critical than reliability in industrial networks.

Access the NPort device

Connect your PC to the same network as the NPort.

Open a web browser and enter the NPort’s IP address, or use NPort Administrator.

Log in using the default credentials (usually admin/moxa).

Navigate to User/Password settings

In the web interface: go to System → User Management (or Maintenance → Password depending on the model).

In NPort Administrator: right-click the device → Configure → Password.

Set a new password

Enter a strong password for the admin account (and other user accounts if available).

Confirm the password and apply the changes.

Save and reboot if needed

Some models require a device reboot to apply the password protection.

After this, all future access (web, telnet, or NPort Administrator) will require the new password.

Optional – Enable remote login restrictions

You can further secure access by limiting which IP addresses can log in.

IP address mismatch: The NPort might have a static IP in a different subnet. Use NPort Administrator to scan the network or temporarily set your PC to the same subnet.

DHCP not enabled/no IP assigned: If DHCP is off and no static IP is set, the device won’t appear. Configure a static IP via serial console if needed.

Network cabling/port issues: Check Ethernet cables, switches, and port LEDs. Use a direct connection if unsure.

Firewall/antivirus blocking discovery: Temporarily disable firewall or antivirus software that may block broadcast packets.

Device not powered or malfunctioning: Ensure proper power supply; check the SYS/Ready LED for status.

Old firmware or corrupted settings: Consider a factory reset if none of the above works, then reconfigure with NPort Administrator.

To reset a Moxa NPort to factory defaults, press and hold the Reset button on the device for about 5 seconds until the Ready LED blinks. This restores all settings on the serial to Ethernet device server back to default values, including IP address and configuration parameters. After the reset, you can reconfigure the NPort device server using NPort Administrator or the web console.

To test serial-to-Ethernet communication on NPort, first connect your serial device to the Moxa NPort serial to Ethernet device server and configure the correct COM port settings. Use NPort Administrator or Virtual COM driver to create a virtual COM port on your PC. Then, run a serial terminal program (like PuTTY or RealTerm) to send and receive data, verifying smooth communication between the serial device and the Ethernet network.

If your Moxa NPort keeps disconnecting from the host, first check the network stability and cabling to rule out physical issues. Next, review the serial to Ethernet device server’s firmware version and update if needed.

Adjust session timeout settings, verify IP configurations, and ensure no port conflicts with firewalls or routers. For persistent issues, the NPort device server diagnostic tools can help pinpoint and resolve connectivity problems.

Yes, Moxa NPort supports Modbus RTU to TCP conversion and enables communication between Modbus RTU serial devices and Modbus TCP-based systems. By acting as a serial to Ethernet device server, NPort simplifies protocol conversion to legacy Modbus equipment with SCADA, PLCs, or other IP-based industrial applications.

You can integrate Moxa NPort with PLCs by connecting the PLC’s serial interface (RS-232/422/485) to the serial to Ethernet device server, which converts the data into TCP/IP for Ethernet communication. Once configured, the PLC can be monitored, controlled, or programmed remotely over the network. This integration helps unify legacy PLC systems with modern SCADA, HMI, or MES applications for industrial automation.