The Overvis OPCB-221B is a communication controller device suitable for industrial applications. Its main function is to connect MODBUS equipment with the Overvis cloud monitoring system or other SCADA systems. OPCB-221B operates as a MODBUS RTU↔TCP converter.
The Controller OPCB-221B (hereinafter referred to as the “Controller”, “Product”, “Device”, or “OPCB-221B”) provides MODBUS communication between clients and servers in TCP networks (Internet) and between devices in the RS-485 interface.
OPCB-221B is used to remotely monitor and control the operation of:
Refrigeration controllers
HVAC systems controllers
Agricultural smart devices
Power network relays, meters, and other electrical equipment
When connecting to the RS-485 bus, use a twisted pair cable, cat. 1 or higher. Strip the ends of insulation by 4±0.5 mm and tighten with bushing tips. A shielded grounded cable is recommended.
DO NOT LEAVE ANY BARE WIRE PROTRUDING BEYOND THE TERMINAL BLOCK.
For reliable contact, tighten the terminal screws with the force indicated in the technical characteristics table.
When connecting to Ethernet, use the supplied cable, or a twisted pair cable of cat. 5e with an 8P8C (RJ45) plug.
When fixing the wires, avoid mechanical damage, twisting, or wearing down the insulation of wires.
Unpack and inspect the product for damage after transportation. If any damage is found, contact the supplier or the manufacturer.
Before connecting to the power supply, keep the product under operating conditions for two hours (in case of possible condensation on the elements).
Carefully study the operating manual.
If you have any questions about the installation of the product, please contact technical support.
Figure 2 – Product Connection Diagram
Connect OPCB-221B according to Figure 2, in the following order:
Using a twisted-pair cable of category 1 or higher, connect the terminal block of the RS-485 module to the serial interface bus (or directly to a device with this interface).
If the product should have access to the Internet or LAN, use the Ethernet connection cable (included in the package) or a twisted pair cable of cat. 5e with an 8P8C (RJ45) plug to connect the “ETH” connector (8P8C/RJ45) to the local network or computer.
Ensure the memory card is present in the “MEM” slot (installed by the manufacturer).
Connect the RS-485 module to one of the “EXT1” or “EXT2” (USB Type-A) connectors.
Connect the power unit (included) to the “PWR” (DC Plug) connector.
Optionally: Secure the USB connections with plastic cable ties to avoid accidental disconnection.
Connect the power unit to the power supply network (220-240VAC, 50Hz).
OPCB-221B has a 32-bit processor running a POSIX-compliant OS (Armbian). It routes traffic between the USB extension modules, such as serial RS-485 / RS-232 interfaces (MODBUS RTU/ASCII protocols), and Ethernet/Wi-Fi LAN interfaces (MODBUS TCP protocol), possibly routed further to the Internet.
OPCB-221B has a built-in web interface that can be used for configuration.
OPCB-221B can connect to a cloud server for remote monitoring and configuration of the product and connected devices.
OPCB-221B provides a Wi-Fi Access Point (hotspot) to simplify the initial setup. Wi-Fi Access Point can be disabled in the settings.
OPCB-221B stores the operating system and data on the pre-installed microSD memory card. Removing or replacing the memory card will render the product inoperable.
After powering up, OPCB-221B loads the operating system and sets up the communication interfaces. This process usually takes up to 1 minute.
With an internet connection provided, OPCB-221B automatically connects to the cloud server if allowed in the settings. By default, unconfigured OPCB-221B creates a Wi-Fi access point with SSID “OPCB_XXXXXX” (where XXXXXX are the last 6 characters of the device’s MAC) and a password specified on the Registration sticker (attached to this manual).
Soft Reboot: Use the web interface by pressing the “Reboot device” button on the “Control” page. This will finish all ongoing operations, store the data, and reboot the device within 1 minute.
Hard Reboot: Turn off the power by unplugging the device, wait 5 seconds, and then turn the power back on.
OPCB-221B provides an HTTP web interface and HTTP REST API for web applications. OPCB-221B accepts HTTP connections via Ethernet or Wi-Fi interfaces on TCP port 80.
To access the HTTP web interface:
Connect to the OPCB-221B Wi-Fi access point with a PC or mobile device and open the following URL in the browser: http://192.168.4.1/
Alternatively, using any PC or mobile device in the local network, open the IP address of the OPCB-221B in the browser. The OPCB-221B IP address can usually be found by accessing the local network router interface.
The default username for the web interface is “admin” with the password specified on the Registration sticker (attached to this manual).
OPCB-221B receives MODBUS TCP requests via Ethernet or Wi-Fi interfaces and transmits them in MODBUS RTU or MODBUS ASCII format over the serial interface. Responses are converted to MODBUS TCP and sent back to the requesting side.
OPCB-221B can also be configured to receive MODBUS RTU or MODBUS ASCII requests via the serial interface and transmit them in MODBUS TCP format to specified IP addresses via Ethernet or Wi-Fi interfaces. In this case, the responses (converted to the request protocol) are sent back to the serial line.
Connections from a PC or mobile device can be made using any software MODBUS TCP clients.
MODBUS registers of the OPCB-221B are configurable in the web interface on the “Connections” page in the section “OPCB Modbus access.”
MODBUS routing between the connected devices is configured in the web interface on the “Connections” page in the section “Routing.”
OPCB-221B Operation Using the Overvis Cloud Server
OPCB-221B can establish connections to the Overvis cloud server using any interface with Internet access. OPCB-221B communicates with the Overvis cloud using an Overvis VPN connection, which provides full encryption of traffic between the device and the Overvis cloud server.
Overvis VPN cloud connection is enabled by default and can be disabled in the settings.
The cloud operation can be configured and managed by creating an account on the Overvis cloud: https://www.overvis.com/
The OPCB-221B product set includes an Overvis Cloud registration sticker. Sticker information includes:
Model of the device (OPCB-221B)
MAC address of the LAN interface
Private key: The unique private key of the device for Overvis VPN access, also used as a unique registration code for the Overvis cloud. This key is needed to restore the device license in case of firmware reflashing
PIN code: The unique PIN code for quick identification of the device on the Overvis cloud
Wi-Fi SSID and password for the initial connection to the Wi-Fi Access Point
Default username and password for web interface access
Quick setup link (with QR-code) for easy connection to the Overvis cloud
Access the link on the sticker and follow the instructions on the Overvis website to set up the device cloud operation and access the OPCB-221B interface through the Overvis cloud.
A partial factory reset can be performed in one of the following ways:
Using a control key USB flash drive:
Write an empty file or an empty folder named "RESET_CONF" to a USB flash drive, then connect it to one of the “EXT1” or “EXT2” slots to reset the settings to the factory defaults. The reset may take up to 30 seconds; the USB flash drive can be disconnected afterward.
Through the web interface:
Use the “Control” page in the web interface.
Device firmware is updated continuously by the manufacturer. By default, the new version is installed automatically after the device is powered on or within 24 hours of operation. Automatic updates guarantee the backward compatibility of all OPCB-221B functions. Releases without backward compatibility require manual installation.
A manual update requires a full factory reset by uploading a new firmware image to the SD memory card. All current firmware images can be found on the release page: https://github.com/overvis/opcb-release/releases
After the device is plugged in and operational, access the web interface by connecting to the Wi-Fi Access Point or using the local network.
By default, an unconfigured OPCB-221B creates a Wi-Fi access point with SSID “OPCB_XXXXXX” (where XXXXXX are the last 6 characters of the device’s MAC) and a password specified on the Registration sticker (attached to this manual).
Connect to the OPCB-221B Wi-Fi access point with a PC or mobile device and open the following URL in the browser: http://192.168.4.1/
After logging in, the quick setup page will be displayed. If the device was configured previously and reconfiguration is needed, the quick setup page can be accessed from the drop-down drawer in the header under the logo.
After the initial setup, the device will connect to the internet using the specified settings and will be available in the Overvis cloud.
Access the link on the sticker and follow the instructions on the Overvis website to set up the device cloud operation and access the OPCB-221B interface through the Overvis cloud.
At the end of its service life, please contact the manufacturer.
During the warranty period (in case of failure), the manufacturer repairs the product free of charge.
Warranty service is performed at the place of purchase or by the manufacturer.
Post-warranty maintenance of the product is performed by the manufacturer at current rates.
Before sending the product for repair, it must be packed in the factory or other packaging that prevents mechanical damage.
If returning the product or submitting it for warranty (post-warranty) service, please state in detail the reason for return in the complaint information field.
The product in its original packaging is permitted to be transported and stored at temperatures ranging from -45 to +60 °C and with relative humidity of no more than 80%. During transportation, the product should be protected from mechanical damage.
