USB RS485 Converter – BMM/1
BMM/1 is a USB RS485 converter, powered by the USB port itself. It appears on the computer as a virtual COM port and automatically manages data direction and baud rates up to 250 kbps.
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 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 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.
FAQ
Are drivers needed?
Yes, and the operating system usually downloads them automatically. If that doesn’t happen, you can download them from the manufacturer’s website.
What’s the difference between this and BLM/1?
BLM/1 is the isolated version. It protects the PC from any power surges on the RS485 bus and isolates it from potential ground potential differences, which are the most common cause of damaged serial ports in industrial environments. In industrial environments, the isolated serial port is the safest choice.
Can I use this to configure a RS485 device?
Yes, that’s one of the most common uses. However, it can also be used to establish continuous communication with a fieldbus.
Description
BMM/1 is a USB RS485 converter, self-powered via the USB port at 5 V. It can be used to enable communication between a PC and an RS485 serial bus. The converter is equipped with removable terminals and is powered via the USB port, so there is no need for an external power supply, so installation is very simple.
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 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 converter 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.
When is a USB RS485 converter needed?
A USB RS485 converter is typically used to enable a PC to communicate with an RS485 serial network, or to program a device via the RS485 bus. To protect the PC from power surges in the network, you can use an isolated USB RS485 converter such as the BLM/1.
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.
Modbus and other protocols
BMM/1 USB RS485 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 converter can also be used in complex networks where multiple protocols are present simultaneously on the same RS485 bus.
Ease of installation
The 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 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
This USB RS485 converter is also available with an RS485 serial interface isolated up to 560 V, 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. 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 |
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 |
