Before you connect

Record the SB1000 serial number and firmware version, the field-device models, and the system they will connect to. Have the field-device wiring and register documentation available. Arrange any interruption to an existing bus before changing modes or starting a scan.

1. Establish local access

1. Connect the specified power supply and check that the device starts. SB1000 accepts 9–24 V AC/DC; follow its product label and the installation's wiring requirements.
2. Prefer Ethernet for the first connection when it is available. Check the physical link, then obtain the actual IP configuration from the device or the installation records. Do not assume a DHCP address or copy an example IP from a guide.
3. Put the computer on a network that can reach that address. Check subnet, routing, and duplicate static addresses. Open the device's configured HTTP or HTTPS address and port.
4. If the device cannot be reached over the network, the Varibits app can read supported settings over NFC on compatible hardware when the device's NFC policy permits it. Use the current snapshot to check the network configuration.
5. If using the commissioning hotspot, join the network shown by the device's instructions. A phone's “no internet” warning does not itself mean local access failed. Use the local address supplied for that hotspot if the captive page does not open.

Wi-Fi uses 2.4 GHz. A metal cabinet can substantially reduce reception. Ethernet access is a useful comparison when diagnosing a radio problem.

The Wi-Fi password, web login, MQTT credentials, and NFC write permission serve different purposes. Changing one does not change the others.

2. Choose who starts the communication

• A BMS/PLC sends Modbus TCP requests to RTU equipment: select TCP → RTU for the connected serial port. The default gateway ports are 4001 for Port 1 and 4002 for Port 2.
• An existing RTU controller sends requests to a TCP server: select RTU → TCP and configure the remote server and its listening port. This is the opposite request direction.
• SB1000 reads field points and publishes MQTT messages: select the MQTT mapping mode and configure the broker, devices, and points.
• A BACnet/IP system needs objects representing Modbus points: select the BACnet mapping mode and configure the BACnet identity and point definitions.
• A serial application expects a virtual COM port: use the matching RFC2217 client and mode.
• Equipment needs unmodified serial frames over a TCP connection: use the raw bridge mode and its client/server and frame-timing settings.
• A serial controller must communicate across two serial segments: use the supported RTU bridge arrangement and define the controller and device sides.

Selecting a protocol mode does not configure the external system's point definitions. A Modbus TCP client still needs the field device's register map. A raw TCP bridge or virtual COM port is not a Modbus TCP server.

The optional management interface on default TCP port 502 exposes SB1000 settings. It is separate from the serial gateway ports. Use the actual saved ports, not just these defaults.

3. Verify one result

1. Save the selected mode and matching serial settings. Note any service restart or reconnect.
2. If you used commissioning, finish the tests and exit commissioning so normal port operation resumes.
3. Choose one documented read-only point. Verify its raw response and engineering value in the destination system before adding a larger point list.
4. Record the working IP, port, bus, Unit ID, protocol, and versions.

When settings change access

Before changing an IP address, Wi-Fi network, web port, or HTTPS setting, record how you will reconnect. Reopen the new address after the change and any restart. A disappearing page can be an expected result of changing the connection you are using.

Keep a recoverable configuration before major changes. The native app's reusable template contains only supported settings and is different from a device configuration backup.