RS-485 supports inexpensive local networks and multidrop communications links, using the same differential signaling over twisted pair. It is generally accepted that RS-485 can be used with data rates up to 10 Mbit/s[a] or, at lower speeds, distances up to 1,200 m (4,000 ft). As a rule of thumb, the speed in bit/s multiplied by the length in meters should not exceed 108. Thus a 50-meter cable should not signal faster than 2 Mbit/s.

Wikipedia: https://en.wikipedia.org/wiki/RS-485

Include:

• Module RS-485 (variation for ASTRA controller and ESP32R4 controller)
• RJ-Cable (1m) to: DB9 MALE DTE, DB9 FEMALE DCE, SCREW TERMINAL BLOCK, RJ-12 6P

CONNECT instruction:

ASTRA basic controller:

1. Open enclosure. DIP switch setting: all toggle to down (RS MODE).
2. Plug in the module to UART2/RS header
3. Connect the RJ-cable to port RS (left port)
4. Configure firmware: RXD – GPIO16, TXD – GPIO17

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ESP32R4 controller:

1. Configure the soldering jumpers to RS MODE: Cut off jumpers from SPI – G, 18, 19, 23. Solder jumpers RS – G, 19, 23.
2. Plug in the module to UART2/RS header
3. Connect the RJ-cable to port RS (left port)
4. Configure firmware: RXD – GPIO16, TXD – GPIO17

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PINOUT:

RJ-12 Pinout (left to fight 1-6):

 

1. – NC
2. – NC
3. – A+
4. – B-
5. – GND
6. – NC

DB9 pinout:

There are two standard pinout arrangements for the DB-9 connector, DTE and DCE. The Male will be DTE and the Female will be DCE. For a basic RS232 connection, you will only need A+, B-. The Male connector has pins and the Female connector has sockets. The pins are numbered oppositely when looking directly at the connectors.

DTE Male DB9 

2 – B-

3 – A+

5 – GND

DCE Female DB9

2 – A+

3 – B-

5 – GND

TERMINAL BLOCK

1 – GND

2 – B-

3 – A+

RJ-12

3 – A+ (green)

4 – B- (red)

5 – GND (black)