USB RS485 isolated converter – BLM/1
BLM/1 is an USB RS485 isolated converter rated up to 560 V, self-powered at 5 V via the USB port.
It can be used to enable a PC to communicate with an RS485 device or bus network, while also isolating the communication from power surges.
The converter is equipped with removable terminals and is powered via the USB port, so there is no need for an external power supply, and installation is very simple.
It is completely protocol-transparent, so it can be used with Modbus or any proprietary protocol that operates on an RS485 bus. The USB RS485 isolated converter appears on the PC as a virtual RS232 port (VCP, Virtual COM Port) and can be used by any program installed on the PC itself.
The RS485 USB serial adapter operates in half-duplex mode and automatically detects data direction and baud rates up to 250 kbps, so it can be easily installed in any new or existing system. The operating system usually recognizes the device and automatically installs the necessary drivers; if not, the drivers can be downloaded from this link.
Description
BLM/1 is an USB RS485 isolated converter rated up to 560 V, self-powered at 5 V via the USB port. It can be used to enable a PC to communicate with an RS485 serial bus. The converter is powered via the USB port, so no external power supply is needed.
The operating system usually recognizes the device and automatically installs the necessary drivers; if not, the drivers can be downloaded from this link. The USB RS485 isolated converter appears on the PC as a virtual RS232 port (VCP, Virtual COM Port) and can be used by any program installed on the PC. The USB RS485 isolated converter operates in half-duplex mode and automatically detects data direction and baud rates up to 250 kbps, making it easy to install in any new or existing system.
Use cases
A USB RS485 isolated converter is typically used to enable a PC to communicate with an RS485 serial network or to program a device via an RS485 bus. The USB RS485 isolated converter also protects the PC from power surges in the network, which are common in extended RS485 buses, such as in industrial settings or in photovoltaic systems.
In a network with heavy electromagnetic interference, which is common in industrial environments, it is good practice to install two or more optical-to-electrical converters to ensure signal integrity. There are also environments where electrical equipment is prohibited, such as swimming pools, saunas, and buildings at risk of fire, where fiber optics therefore become necessary.
Protocol
The BLM/1 USB RS485 isolated converter is completely protocol-independent. This means that the converter is transparent to the communication and can be used with protocols such as Modbus, BACnet, or any proprietary protocol.
This is possible because the converter operates at the logic level rather than at the protocol level. Therefore, this USB RS485 isolated converter can also be used in complex networks where multiple protocols are present simultaneously on the same RS485 bus.
Ease of installation
Removable terminals make installation and replacement extremely easy.
With a modern operating system, USB drivers are usually installed automatically once the device is connected to the PC. From a software perspective, therefore, this USB RS485 isolated converter is fully Plug & Play. If the PC is unable to communicate with the device, it is often sufficient to install the drivers manually, but we are, of course, available to provide support for resolving configuration issues.
Versatility
The USB RS485 isolated converter is also available with a non-isolated RS485 serial interface, with other combinations of serial standards, or with different connectors. The BLC/1 and BMC/1 converters, for example, use 3-pin Mini XLR connectors, with isolated and non-isolated RS485, respectively. The BTS/1 and BTV/1 feature synthetic or glass fiber optic connectors to provide additional isolation from electromagnetic interference.
The BFM/1 and BFC/1 industrial serial converters operate with the RS422 standard, featuring either removable terminals or 5-pin Mini XLR connectors. All combinations of serial standards, fiber optics, and power supply options are available in the catalog; however, special requests (such as higher data rates) can be made via the contact form.
Technical Specifications
Main features
| Power supply | USB |
|---|---|
| Power consumption | 1 W |
| Serial transmission data rate | 0 – 250 kbps (automatic) – higher data rates on request |
| Isolation voltage | 560 V (DIN EN 60747) – 2500 V for 1 minute (UL 1577) |
USB
| Connector | USB type A |
|---|---|
| Technology | USB 2.0, USB 1.1 |
| Interface type | VCP (Virtual COM Port) based on RS232 |
| Data direction | Full Duplex |
| Supported operating systems | Windows 98 and above, Mac OS 8 and above, Linux |
RS485
| Communication type | Half Duplex on a balanced line, with automatic data direction |
|---|---|
| Maximum bus voltage | ± 60 V – ESD ± 16.5 kV (Human Body Model) |
| Common mode range | ± 25 V DC |
| Slew rate | Limited, to have an error-free transmission |
Mechanical features
| Dimensions | 90 mm x 50 mm x 25 mm |
|---|
Working conditions
| Degree of protection | IP20 |
|---|---|
| Operating temperature | -20 °C to +50 °C |
| Storage temperature | -40 °C to +80 °C |
