RS-485 is a cost-effective solution in serial communication networks. It can be used up to data rates at 10 Mbit/s or distances up to 1200m at lower speeds. This RS-485 Shield is a standard add-on board for Raspberry Pi. It is integrated with simple screw terminal as well as DB9 interface.
The 485 interface uses differential signal transmission. Please make sure the port A connect to the port A of the 485 device, and port B connect to the port B of the 485 device.
485-A: The end A of RS485 data transmit wire, connect to the pin A of the MAX485 chip.
485-B: The end B of RS485 data transmit wire, connect to the pin B of the MAX485 chip.
GND: Connect to the Raspberry Pi GND.
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As you can see, GPIO14 and GPIO15 are applied for data transmission, and we use GPIO18 as the enable signal.
For the definition of logic signals, please refer to the table below.
Female Headers to Raspberry
We use a 2X13 Female Header to plug this module into the Raspberry Pi, please make sure the pins are aligned.
Extension Female Headers
This RS-485 Shield occupies 26 Raspberry Pi pins, and only 5 GPIO pins are actually used. We take these 26 pins out in case you need those pins for other purposes.
GPIO Occupied List
SDA for Grove I2C Port
SCL for Grove I2C Port
Connect to the pin DI of Max485 chip, for data transmission.
Connect to the pin RO of Max485 chip, for data transmission.
Connect to the pin RE & DE of Max485 chip, work as the enable signal.
Grove I2C Port
We have reserved the I2C interface so that you can easily use it with I2C devices. It should be noted that the VCC of this port is 5V, you need to confirm that whether the module is compatible with 5V voltage.
SCL: I2C serial clock, connect to the GPIO03 of Raspberry Pi.
SDA: I2C serial data, connect to the GPIO02 of Raspberry Pi.
VCC: Connect to the Raspberry Pi 5V pin.
GND: Connect to the Raspberry Pi GND pin.
We use the MAX485ESA IC for this shield, for more detail about this IC, please check the MAX485 Datasheet