Hardware

The RS-485 / Modbus module has been tested with various devices and is compatible with the majority of commercial modules, but this does not ensure the working with all of them. Be sure that the RS-485 module fits your technical requirements. The final user is the responsible for perform the task of communicating the RS-485 module with other commercial devices.

Electrical features

  • Board power voltages: 3.3 V

  • Maximum admitted voltage: -0.3 V to +4 V

  • Max data rate: 2.5 Mbps

  • Temperature range: [-40 °C, 85 °C]

  • Dimensions: 33 x 31.5 mm

Consumption

The RS-485 module uses a low power transceiver. The board is guaranteed to run at data rates of 460800 bps. The typical consumption on the board is 7mA but this consumption can increase, due to current peaks while the module is transmitting data trough the bus. The typical peak current consumption is about 30mA.

Connector

The RS-485 standard does not specify the type of connector or pin-outs. RS-485 connectors can be DB9, DB25, Terminal Blocks, RJ-11, R-J45 or one of the round DIN connectors. The DB9 connector is one of the most common connectors and is used in many applications because it provides size and cost benefit. The RS-485 module uses pins 2 and 3 to transmit and receive data. Ground pin is not necessary because it is a differential bus.

Figure: DB9 connector

The RS-485 module comes with a standard male-female DB9 cable. This cable is useful for connecting the module to other RS-485 devices which have a DB9 male connector.

Figure: Male-female DB9 cable

Many devices do not have standard connectors. The RS-485 module includes a block connector for making wired connections.

Figure: Terminal block connector