# DCS\-BIOS RS485 Nano Module

## Description

Arduino Nano\-based DCS\-BIOS RS\-485 interface module using a MAX487CPA\+ transceiver and two RJ45 sockets for bus daisy\-chaining\.

## Project Details

- **Owner:** alfamike
- **Created:** 7/11/2026
- **Last Updated:** 7/11/2026
- **Visibility:** Public

## Key Components

### A1 — [Arduino Nano V3](https://flux.ai/electech/arduino-nano-v3~nh.md)

- Manufacturer Name: Arduino
- Part Type: Microcontroller
- Role: Logic\-level Shifting
- Role Details: DCS\-BIOS Arduino Nano V3; D0 RX, D1 TX, D2 TXENABLE\. Power selected by SW1: 12V\_BUS to VIN or 5V\_BUS to local 5V rail\.

**Pins:**
- 3\.3V [pin 2]
- 5V [pin 12]
- A0 [pin 4]
- A1 [pin 5]
- A2 [pin 6]
- A3 [pin 7]
- A4 [pin 8]
- A5 [pin 9]
- A6 [pin 10]
- A7 [pin 11]
- D10 [pin 28]
- D11 [pin 29]
- D12 [pin 30]
- D13 [pin 1]
- D2 [pin 20]
- D3 [pin 21]
- D4 [pin 22]
- D5 [pin 23]
- D6 [pin 2]
- D7 [pin 25]
- D8 [pin 2]
- D9 [pin 27]
- GND [pin 19]
- GND [pin 14]
- Ref [pin 3]
- RST [pin 18]
- RST [pin 13]
- RX0 [pin 17]
- TX1 [pin 16]
- VIN [pin 15]

### J1 — [SS\-7188\-NF](https://flux.ai/adrian95/ss-7188-nf~dn3.md)

- Part Type: Connector
- Datasheet URL: https://www\.cinch\.com/media/drawings/products/ethernet\-usb/dr\-stw\-ss\-7188\-nf\.pdf
- Package or Case Code: BEL\_SS\-7188\-NF
- License: https://creativecommons\.org/licenses/by/4\.0/
- Role: Connector
- Manufacturer Name: Stewart Connector
- Manufacturer Part Number: SS\-7188\-NF
- Role Details: RJ45 bus\-in pinout: 1=RS485\_A, 2=RS485\_B, 3=12V\_BUS, 4=3V3\_BUS, 5=5V\_BUS, 6=NC, 7/8=GND

**Pins:**
- 1 [pin 1]
- 2 [pin 2]
- 3 [pin 3]
- 4 [pin 4]
- 5 [pin 5]
- 6 [pin 6]
- 7 [pin 7]
- 8 [pin 8]

### J2 — [SS\-7188\-NF](https://flux.ai/adrian95/ss-7188-nf~dn3.md)

- Part Type: Connector
- Datasheet URL: https://www\.cinch\.com/media/drawings/products/ethernet\-usb/dr\-stw\-ss\-7188\-nf\.pdf
- Role Details: RJ45 bus\-out daisy\-chain pinout: 1=RS485\_A, 2=RS485\_B, 3=12V\_BUS, 4=3V3\_BUS, 5=5V\_BUS, 6=NC, 7/8=GND
- Package or Case Code: BEL\_SS\-7188\-NF
- License: https://creativecommons\.org/licenses/by/4\.0/
- Manufacturer Name: Stewart Connector
- Manufacturer Part Number: SS\-7188\-NF
- Role: Connector

**Pins:**
- 1 [pin 1]
- 2 [pin 2]
- 3 [pin 3]
- 4 [pin 4]
- 5 [pin 5]
- 6 [pin 6]
- 7 [pin 7]
- 8 [pin 8]

### SW1 — [EG2208](https://flux.ai/adrian95/eg2208~gfq.md)

- Manufacturer Name: E\-Switch
- License: https://creativecommons\.org/licenses/by/4\.0/
- Role: Switching
- Datasheet URL: https://sten\-eswitch\-13110800\-production\.s3\.amazonaws\.com/system/asset/product\_line/data\_sheet/119/EG\.pdf
- Role Details: EG2208 DPDT ON\-ON\. One position: 12V\_BUS to Nano VIN and 5V\_BUS open\. Other position: 5V\_BUS to 5V\_LOCAL and 12V to VIN open\. Do not exceed Nano VIN regulator thermal limits\.
- Part Type: Switch
- Manufacturer Part Number: EG2208

**Pins:**
- COM\_1 [pin 2]
- COM\_2 [pin 5]
- MH1 [pin MH1]
- MH2 [pin MH2]
- NC\_1 [pin 1]
- NC\_2 [pin 4]
- NO\_1 [pin 3]
- NO\_2 [pin 6]

### SW2 — [EG2208](https://flux.ai/adrian95/eg2208~gfq.md)

- Manufacturer Name: E\-Switch
- License: https://creativecommons\.org/licenses/by/4\.0/
- Role: Switching
- Datasheet URL: https://sten\-eswitch\-13110800\-production\.s3\.amazonaws\.com/system/asset/product\_line/data\_sheet/119/EG\.pdf
- Role Details: Programming isolation: connects Nano RX0/TX1 to MAX487 RO/DI in RUN position; disconnects them in PROGRAM position
- Part Type: Switch
- Manufacturer Part Number: EG2208

**Pins:**
- COM\_1 [pin 2]
- COM\_2 [pin 5]
- MH1 [pin MH1]
- MH2 [pin MH2]
- NC\_1 [pin 1]
- NC\_2 [pin 4]
- NO\_1 [pin 3]
- NO\_2 [pin 6]

### SW3 — [DS04\-254\-2\-01BK\-SMT](https://flux.ai/jecstronic/ds04-254-2-01bk-smt~t2.md)

- Role Details: RS\-485 termination enable: closes to place R1 120Ω between RS485\_A and RS485\_B
- Manufacturer Part Number: DS04\-254\-2\-01BK\-SMT
- Manufacturer Name: CUI Devices
- Part Type: Switch
- Datasheet URL: https://www\.cuidevices\.com/product/resource/ds04\-254\-smt\.pdf
- License: https://creativecommons\.org/licenses/by/4\.0/
- Role: Switching

**Pins:**
- \~ [pin 1B]
- \~ [pin 1A]

### U1 — [MAX487CPA\+](https://flux.ai/lcsc/max487cpaplus~t2i2.md)

- Role Details: MAX487CPA\+ 5V half\-duplex transceiver; RO/DI to Arduino UART; DE and /RE to D2 TX enable
- LCSC Part Number: C1543795
- Manufacturer Part Number: MAX487CPA\+
- Role: Logic\-level Shifting
- JLCPCB Part Class: Extended Part
- Package or Case Code: PDIP\-8\_L9\.6\-W6\.4\-P2\.54\-LS7\.9\-BL\-1
- Manufacturer Name: ADI\(亚德诺\)/MAXIM\(美信\)

**Pins:**
- \~\{RE\} [pin 2]
- A [pin 6]
- B [pin 7]
- DE [pin 3]
- DI [pin 4]
- GND [pin 5]
- RO [pin 1]
- VCC [pin 8]

*The full schematic, PCB layout, bill of materials, and interactive design are available at [https://flux\.ai/alfamike/dcs\-bios\-rs485\-nano\-module\~gv](https://flux.ai/alfamike/dcs-bios-rs485-nano-module~gv).*

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*Generated from [https://flux\.ai/alfamike/dcs\-bios\-rs485\-nano\-module\~gv](https://flux.ai/alfamike/dcs-bios-rs485-nano-module~gv)*