Connections and Network Setup

Important

Connecting an incorrectly configured device to a data transmission network can disrupt communication between other devices. Ensure all connected devices have compatible settings. Network connections involving more than 2 devices should be performed by qualified network personnel.

Quick Start

For a streamlined connection guide, see the Quick Start Guide.

IP Addressing

The EM-482 uses standard TCP/IPv4 addressing for Wi-Fi communication. DHCP is enabled by default, allowing the device to automatically obtain network settings from your router. Without DHCP the factory default IP address is 192.168.0.111.

IP Addressing Fundamentals

When devices communicate over a network using the TCP/IPv4 protocol, each device uses IP addressing settings to identify the sender and receiver of data. EM-482 stores the following in its memory:

• IP Address: A unique address within the subnet (four bytes written as integers 0-255, separated by dots)
• Subnet Mask: Identical for all devices within the subnet (written similar to IP address)
• Gateway Address: Used to communicate with other networks

Requirements for Proper Communication:

Devices within a subnet communicate properly when these conditions are met:

• Common Subnet Mask: All devices in the subnet must use the same mask. Most small LANs use 255.255.255.0.
• Valid Mask Format: The mask starts with consecutive 1 bits, followed by consecutive 0 bits.
• Subnet Address: All IP address bits corresponding to the mask’s 1 bits must be identical across all devices. Common LANs use 192.168 as the address prefix with mask 255.255.255.0. The third byte can serve as a subnet number in complex LANs; in smaller LANs, it’s typically 0.
• Unique Host Address: The IP address bits corresponding to the mask’s 0 bits must be unique to each device within the subnet.
• Gateway Configuration: A router or gateway device that communicates with other networks typically uses an address like 192.168.0.1, 192.168.0.100, or 192.168.0.101. Other devices can use this address as their gateway. The gateway address is not required for intra-subnet communication—only for connecting to external networks (such as the Internet).

Wi-Fi Connection Methods

EM-482 supports three connection methods via Wi-Fi.

Method 1: Wi-Fi setup access point mode

This mode is only used to configure EM-482 essential communication parameters. It is not intended for Modbus communication.

1. Press the R button on the front panel for about 3 seconds.
2. After the button is released, on entering this mode the WI-FI and SRV LEDs would start blinking.
3. The Wi-Fi access point EM482_XXXXXX would become available, where XXXXXX are the last symbols of the device MAC address (shown on its label).
4. Connect to this access point with your device, open the browser and enter em.com (or 192.168.4.1) in its address line.
5. Select the Wi-Fi access point for EM-482 to connect to.
6. Save settings then restart the device.

Method 2: Network with DHCP Server

If your network access point has DHCP server that assigns IP addresses to new devices:

1. Enter EM-482 configuration mode (see method 1)
2. Select Wi-Fi access point for EM-482 to connect to
3. Enable DHCP server addressing
4. Save settings and reboot EM-482
5. EM-482 would connect to the cloud server, and can be managed there (if the access point provides Internet access)
6. To access EM-482 locally, check its local IP address in the access point router DHCP table, or fix the EM-482 address as static in the access point router settings

Method 3: Network Without DHCP

If DHCP is unavailable, or a static address should be used outside the DHCP range:

1. Enter EM-482 configuration mode (see method 1)
2. Select Wi-Fi access point for EM-482 to connect to
3. Disable DHCP server addressing
4. Set the static IP address, mask and gateway address according to your access point network setup. The EM-482 address should be unique in the network. The gateway is needed only for Internet access (cloud server and firmware updates)
5. Save settings and reboot EM-482
6. EM-482 may connect to the cloud server, and can be managed there (if the manual IP settings are correct and the gateway provides Internet access)
7. To access EM-482 locally, use its manually configured address

Internet Connection via Wi-Fi

STRONGLY RECOMMENDED

Connect the device to the Internet under the supervision of your network system administrator and/or Internet service provider representative.

Basic Internet Setup

To connect EM-482 to the Internet via Wi-Fi:

1. Connect EM-482 to a router using one of the methods above
2. Ensure the router is connected to your Internet service provider (ISP)

This setup enables outgoing connections (e.g., active-mode connection to cloud servers, connections to other servers using their static IP addresses).

graph LR
    A[EM-482] -->|Wi-Fi| B[Router]
    B -->|WAN| C[Internet/ISP]
    B -->|LAN| D[Local Network]
    C --> E[Cloud Server / Remote Modbus TCP Devices]
    D --> F[Modbus TCP Devices]

Fig. 3 – EM-482 Internet connection topology via Wi-Fi with DHCP

Incoming Connections Setup

To access the device from the Internet via incoming connections (direct TCP connection or web interface):

1. Acquire a Static IP: Get a dedicated line with a static IP address from your ISP

   • Connect the ISP cable to the router’s uplink port (usually color-coded, see router documentation)
   • Connect EM-482 to the router

2. Configure Router: Following your ISP’s recommendations, configure the router for Internet access using the router documentation.

3. Set Up Port Forwarding: Configure the router to redirect queries from your static public IP address to EM-482’s local IP address. For Modbus TCP access: redirect to the incoming connections port (register 450, factory default: 502). See Modbus Interface for register configuration details.

   graph LR
       A[Internet Client] -->|Public IP:Port| B[Router]
       B -->|Port Forward| C[EM-482]
       C -->|RS-485| D[Modbus Devices]

   Fig. 4 – EM-482 incoming connections via port forwarding

4. Configure DHCP Reservation: Either:

   • Configure the router to always assign the same IP address to EM-482 via DHCP, OR
   • Disable DHCP in EM-482 settings and use a static IP

   This ensures port forwarding works correctly.

5. Verify Security: Confirm that EM-482’s Internet connection is protected by standard security measures (see Connection Security). Specifically set the setup password and write access password to some unique values. It is also recommended to set the read access password.

6. Access the Device: When accessing EM-482 from the Internet, use the static IP address provided by your ISP and the public port specified in your port forwarding configuration

Connection Security

EM-482 provides several security features to protect against unauthorized access:

Built-in Security Features

EM-482 has basic protection against unauthorized access via network. Access for writing and/or reading via Modbus can be deactivated in settings.

Device settings can be changed remotely by entering a password (minimum 5 characters). Access passwords can be set for restriction of writing and/or reading via Modbus.

When entering the password, all settings are only available to the specific client. In case of no requests from the client over a long period, the access returns to locked mode.

SECURITY WARNING

For Modbus connections, passwords are transmitted in unencrypted form. Even with correct password authentication, the HTTP and Modbus connections remain unsecured at all segments except Wi-Fi.

Security Limitations and Recommendations:

• Attack Protection: The device protection system is not designed to counter malicious network attacks, especially denial-of-service attacks aimed at blocking EM-482 rather than gaining access
• Network Segmentation: For complex and large networks (especially when providing Internet access to EM-482), it is strongly recommended to:
  • Separate EM-482 from unprotected networks using standard security equipment
  • Use a properly configured router with traffic filtering
  • Deploy a firewall or similar protective measures

Server Connection

EM-482 supports constant communication with data collection and management servers, for example, Overvis Cloud.

About Overvis

Overvis (www.overvis.com) is a system for monitoring and remote control of technological processes that enables you to read data from and control devices including EM-482, store data in a database, review the data in various formats, and receive alarm notifications via SMS or email.

EM-482 factory settings are preconfigured for Overvis connection, once the Internet access is provided, EM-482 would connect to the cloud server. The Overvis system uses MAC address-based authentication — the device’s unique MAC address is sent to the server at each connection session.

Connection Methods Overview

There are two ways to connect EM-482 to Overvis Cloud:

1. Using PIN/QR Code from Label (Recommended for first-time setup) — The fastest method using reverse connection where EM-482 connects to Overvis. Simply scan the QR code on your device label. Detailed in Quick Start Guide.

2. Direct Connection from Overvis (For advanced users) — Overvis connects directly to EM-482 through router port forwarding, requiring a static public IP address. Used rarely due to complexity and security considerations.

Method 1: Using PIN/QR Code from Device Label

This is the recommended method for first-time setup, using the registration information from your EM-482 label.

sequenceDiagram
    participant EM-482
    participant Overvis
    participant User

    EM-482->>Overvis: Connect & send handshake (MAC address)
    Overvis->>EM-482: Confirm handshake
    Note over EM-482,Overvis: Connection established, waiting for binding

    User->>Overvis: Scan QR code / Enter PIN URL
    User->>Overvis: Login to account
    User->>Overvis: Submit PIN in "Create Network" page
    Overvis->>Overvis: Link PIN to MAC address
    Overvis->>Overvis: Find matching connection by MAC
    Overvis->>User: Create network under user's account

    loop Data Communication
        User->>Overvis: Request device data
        Overvis->>EM-482: Read registers (via established connection)
        EM-482->>Overvis: Return data
        Overvis->>User: Display data
    end

Fig. 6 – Connection sequence for PIN/QR code method (reverse connection)

Connection Flow: EM-482 initiates outbound connection to Overvis and maintains it. User registers by linking the PIN to this existing connection. No port forwarding required.

Prerequisites:

• EM-482 connected to Internet
• QR code label on device (or PIN code from label)
• Overvis Cloud account (or create during setup)

Connection Steps:

1. Verify Internet Connection

   Ensure EM-482 is connected to the Internet. Check the Wi-Fi and SRV LEDs are both on.

2. Access Overvis Server

   Scan the QR code on the device label with your phone or tablet, OR manually enter the URL from the label (format: https://c.overvis.com/ABCD1234). The link automatically redirects to Overvis server login page with the PIN embedded in the URL.

3. Login or Create Account

   If you have an account, enter your credentials. New users should register for a free account first.

4. Create Network

   After login, Overvis displays the “Create Network” page. If you came from the QR code/link, the PIN is pre-filled automatically. Otherwise, manually enter the PIN from the device label. Click “Check connection” to verify EM-482 is online.

5. Configure Network

   Give your network a descriptive name (a “network” represents your EM-482 plus all connected Modbus devices). EM-482 itself (Modbus unit ID 111) is added automatically. Add your RS-485 devices by selecting models and entering their Modbus addresses.

6. Verify Operation

   Open a device page in Overvis and read parameters to confirm real-time communication.

Method 2: Direct Connection from Overvis

This method allows Overvis to connect directly to your EM-482 using its public IP address. It requires more advanced network configuration.

sequenceDiagram
    participant User
    participant EM-482
    participant Router
    participant Overvis

    User->>Router: Configure port forwarding<br/>(Public IP:Port → EM-482:502)
    User->>EM-482: Set static/reserved IP
    User->>Overvis: Add network with direct connection method
    User->>Overvis: Enter public IP & port
    Overvis->>Router: Connect to Public IP:Port
    Router->>EM-482: Forward to EM-482:502
    EM-482->>Router: Modbus TCP response
    Router->>Overvis: Forward response
    Overvis->>User: Show device online
    loop Data Communication
        User->>Overvis: Request device data
        Overvis->>Router: Read registers request
        Router->>EM-482: Forward request to EM-482:502
        EM-482->>Router: Return data
        Router->>Overvis: Forward response
        Overvis->>User: Display data
    end

Fig. 11 – Connection sequence for direct connection method (incoming connection)

Connection Flow: Overvis initiates inbound connection to EM-482 through router port forwarding. Requires static public IP.

Prerequisites:

• Static public IP address from your ISP
• Router with port forwarding capability
• EM-482 connected to your LAN
• Overvis Cloud account
• Basic understanding of router configuration and network security

Advanced Configuration

This method requires configuring your router’s port forwarding and exposing EM-482 to the Internet. Ensure you follow security best practices and consult your network administrator if operating on a corporate network.

Connection Steps:

1. Obtain Static Public IP

   Contact your Internet Service Provider to obtain a static public IP address for your location. Dynamic IP addresses are not recommended as they may change. Some ISPs offer static IP as a paid add-on service.

2. Configure Router Port Forwarding

   Access your router’s configuration interface and set up port forwarding to redirect external connections to EM-482. Forward to EM-482’s Modbus TCP port (default: 502). External port can be the same (502) or different for security. Forward to EM-482’s internal IP address (e.g., 192.168.0.111).

   graph LR
       A[Overvis Cloud] -->|Public IP:Port| B[Router]
       B -->|Port Forward to 192.168.0.111:502| C[EM-482]
       C -->|RS-485| D[Modbus Devices]

   Fig. 12 – Direct connection port forwarding configuration

3. Configure DHCP Reservation or Static IP

   Ensure EM-482 always has the same internal IP address:

   • Option A: Configure your router to assign EM-482 a reserved IP via DHCP (recommended)
   • Option B: Disable DHCP on EM-482 and manually configure a static IP address in the web interface

4. Verify EM-482 Accessibility

   Test the connection from outside your network. Use a Modbus TCP client from a different network (e.g., mobile hotspot), connect to your public IP address on the forwarded port, and try reading a register from EM-482 (unit ID 111, register 1 for firmware version).

5. Configure Security (Strongly Recommended)

   Set the strong Modbus TCP password in EM-482 settings. Consider changing the external port to a non-standard number. Configure your router’s firewall to restrict access by IP range if possible. See Connection Security for additional recommendations.

6. Create Network in Overvis

   Log in to your Overvis Cloud account at www.overvis.com. On the “Create Network” page, select the direct connection method. Enter your static public IP address and the external port number (as configured in router). Enter EM-482’s Modbus address (default: 111) and Modbus password if configured.

7. Configure Network

   Give your network a descriptive name (a “network” represents your EM-482 plus all connected Modbus devices). EM-482 itself (Modbus unit ID 111) is added automatically. Add your RS-485 devices by selecting models and entering their Modbus addresses.

8. Verify Operation

   Open a device page in Overvis and read parameters to confirm real-time communication. Monitor connection stability over 24-48 hours.

Connecting to Other Servers

The only method of connection EM-482 to other cloud servers and SCADA systems is the direct connection method via Modbus TCP.

Configure EM-482 in the monitoring system as a remote Modbus TCP device. This requires setting up port forwarding on your router to redirect external connections to EM-482’s local IP address and Modbus TCP port (default: 502). Your server will initiate connections to EM-482 through your router, similar to Method 2 described above. You’ll need a static public IP address from your ISP.

Since EM-482 uses the standard Modbus TCP protocol for direct connections, no special server software is required—any Modbus TCP client can communicate with the device. See the Modbus Interface documentation for complete register mappings and communication protocols.

Troubleshooting

Problem: EM-482 WI-FI LED does not remain on, but is blinking rarely (every 3 seconds, for more than 2 minutes).

EM-482 is not connected to your Wi-Fi access point. Either Wi-Fi access point is misconfigured, or the access point is unavailable. If the issue persists, verify the Wi-Fi access point is properly configured in EM-482 settings.

Problem: EM-482 SRV LED remains off (for more than 2 minutes).

EM-482 is not connected to the Internet. Verify the server connection is enabled in the web interface. Check that the server address and port are correct in settings. Your network firewall may be blocking outgoing connections. If the issue persists, check the router internet access.

Problem: EM-482 WI-FI and SRV LEDs keep blinking alternately.

The EM-482 is in setup access point mode. Either complete the configuration, or exit the mode by pressing the R button on the front panel for about 3 seconds.

Problem: Cannot access EM-482 web interface

Check the EM-482 is in setup access point mode (the LEDs are blinking alternately). Check your device is connected to EM-482 access point. Use em.com or 192.168.4.1 address to access the web interface.

Problem: “Device already registered” error

The device is bound to another Overvis account. Use the Restart Activation button in the Cloud settings page to unbind it, or contact the server administration (or the previous owner) to remove the device from their account.

Problem: Intermittent connection drops

Check that the power supply voltage is within the required range (7-30V DC) and can provide sufficient current (up to 110mA). Look for electrical noise or interference sources near the device. Update EM-482 firmware to the latest version.

Problem: RS-485 devices not responding

Verify the RS-485 wiring is correct (A and B terminals). Check that the RS-485 bus termination is properly configured. Verify Modbus RTU/ASCII settings match the connected devices. See the Modbus Interface documentation for detailed communication settings.

Further Reading

• Quick Start Guide – Get your EM-482 up and running in 15 minutes with step-by-step setup instructions
• Modbus Interface — Register mappings and communication protocols for Modbus TCP/RTU/ASCII

Need Help?

If you’re experiencing issues not covered in this guide, we’re here to help:

• Technical Support: Contact the manufacturer’s support team
• Documentation: Visit overvis.com/support for additional resources
• Community: Check the user forums for solutions from other EM-482 users

For warranty service or hardware issues, please contact your authorized distributor or the manufacturer directly.