====== lamaPLC: TTL to RS485 Module ======
{{ :sensor:max485_2.png?120|TTL to RS485 Module}}
The module is often listed as **HW-097**.

The onboard MAX485 chip is a low-power, slew-rate-limited transceiver for **RS-485** communication. It is connected to 5.08 mm pitch 2P binding posts, which makes [[com:basic_rs485|RS-485]] wiring convenient. All the chip's pins are exposed and can be controlled and operated by the microcontroller. It operates on a single 5V power supply with a rated current of 300μA.


RS-485 is a type of asynchronous serial communication protocol because no synchronizing clock signal is transmitted with the data. RS-485 uses differential signaling to transfer binary data between devices. This differential signaling creates a differential voltage using positive and negative 5V supplies. The advantage of this method is its ability to reject common-mode noise.

RS-485 supports a **maximum data transfer rate of 30 Mbps** and can connect many slaves to a single master. The protocol allows up to 32 devices to be connected.

The module is suitable for Arduino and [[com:basic_modbus#rtu|Modbus RTU]] applications. In this setup, the Arduino should use Tx/Rx TTL communication, while the standard Modbus A+, B-, and GND connections should be made on the other side of the module.

===== MAX485 switching logic =====
{{:sensor:max485_1.png|TTL to RS485 Module}}

===== MAX485 modul pinout =====
{{ :sensor:max485_2.png?300|TTL to RS485 Module}}
^RO|TTL side|Receiver output|
^RE|TTL side|Receiver output enable|
^DE|TTL side|Driver output enable|
^DI|TTL side|Drive input|
^Vcc||**5V DC** power supply|
^A+|RS-485 side|The non-inverting input of the receiver and the non-inverting output of the driver|
^B-|RS-485 side|Receiver inverting input and driver inverting output|
^GND||Ground|

===== Modbus topics on lamaPLC =====
{{topic>modbus}}

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{{tag>modbus rtu modbus_rtu HW-097 RS-485 MAX485}}
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