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Appendix O RS 232 Greater Than 100 Feet

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jgyates edited this page Feb 6, 2022 · 9 revisions

Using Genmon with RS-232 with Distances greater than 100 feet.

Various factors can play a role in the placement of your raspberry pi. In many cases it is best to pair the pi with an enclosure and mount the enclosure in the generator enclosure. I some instances this is not the ideal configuration. In these cases it is beneficial to house the raspberry pi at a distance from the generator that is greater than the RS-232 standard will support. There are a few options to support this configuration.

Serial over TCP via Wifi

Using a serial to TCP converter with a wifi connection is a viable solution. This method is described in detail on this page.

RS-422

This approach uses RS-232 to RS-422 converters. Below is a diagram.

RS-422 Wiring Diagram

The equipment used follows.

##TTL to RS-232 Converter

[Anmbest 2PCS MAX3232 3.3V to 5V DB9 Male RS232 Serial Prot to TTL Converter Module Root Connector for Arduino Raspberry Pi and Microcontrollers](https://www.amazon.com/gp/product/B07LBDZ9WG/ref=ppx_yo_dt_b_asin_title_o03_s 01?ie=UTF8&psc=1) *** NOTE *** The ones I received in January, 2022 came with the Dupont connectors needed for connecting it to the Raspberry Pi GPIO pins.

##RS-232 to RS-442 Converter

[DTECH RS232 to RS485 / RS422 Serial Communication Data Converter Adapter Mini-Size](https://www.amazon.com/gp/product/B0196AO1IG/ref=ppx_yo_dt_b_asin_title_o00_s0 0?ie=UTF8&psc=1&qty=2)

##DB-9 to RS-232 Adapter

[Fielect D-sub DB9 Breakout Board Connector 9 Pin 2 Row Male RS232 Serial Port Solderless Terminal Block Adapter with Positioning Nuts 1PCS](https://www.amazon.com/gp/product/B082S73GTP/ref=ppx_yo_dt_b_asin_title_o03_s0 0?ie=UTF8&psc=1) [Futheda 2PCS D-sub DB9 Interface Breakout Board Connector 9 Pin 2 Row Male RS-232 Serial Port Solderless Terminal Block Adapter](https://www.amazon.com/Futheda-Interface-Breakout-Connector- Solderless/dp/B08C9PYHVG/ref=sr_1_51?crid=25UBMQYBOOOXI&keywords=db9+breako ut+connector+male&qid=1643583281&sprefix=db9+breakou%2Caps%2C138&sr=8-51)

##Notes

  • RS-422 communication protocol is full duplex so the conversion to RS232 is straightforward
  • The length of cable used was approximately 120 feet. The cable runs in a separate conduit from the main electrical drop to the house circuit breaker box. The cable does run in a conduit with the coaxial cable supplying internet/phone/TV and, once in the basement, next to normal electrical wiring. Did a successful loopback test at the generator end, showing that a 240 foot wire run worked (in this instance) without supplemental power.
  • If there is a signal problem due to the length of the cable, power (+9 VDC?) can be supplied to one end of the Cat 5e cable between VCC and GND. An extra wire will need to be connected between the VCC terminals on the RS-232 to RS-422 converters.
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