# Fathom to Arduino Serial Connection

**URL:** <https://discuss.bluerobotics.com/t/fathom-to-arduino-serial-connection/11634>\
**Category:** DIY ROVs\
**Created:** [February 27, 2022, 9:02am UTC](https://discuss.bluerobotics.com/t/fathom-to-arduino-serial-connection/11634 "2022-02-27T09:02:45Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jua123](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@jua123](https://discuss.bluerobotics.com/u/jua123)\
**Post date:** [February 27, 2022, 9:02am UTC](https://discuss.bluerobotics.com/t/fathom-to-arduino-serial-connection/11634/1 "2022-02-27T09:02:45Z")

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Hello!!!

I have been looking for information but I have not seen a clear guide,

I need a connection from above, out of the water, to the ROV. I only want a Serial connection, from outside a computer or arduino to the ROV with arduino, the idea is to have a Serial communication to send data and receive, I only want to send data, I don’t need video.

I have been reading that you use FATHOM but some concepts are not clear to me,

- What combination will I need???

I understand that above I would need [FXTI](https://www.bluerobotics.com/store/rov/bluerov2-accessories/fxti-asm-r1-rp/) , it has a connection for Binder 770 and a USB output that I could connect to the USB of my laptop and read through the arduino IDE serial the data that comes to me from the ROV’s arduino.  
In the ROV part, I would need another [Fathom X board](https://bluerobotics.com/store/electronics/fathom-x-tether-interface-board/) and from there connect to the Arduino serial port to have communication with the surface. Correct me if I’m wrong.

- What cable should I use if I only need to send data and receive, would the thin cable work for me? [https://bluerobotics.com/store/cables-connectors/cables/cab-nbpuf-1utp-26awg/](https://bluerobotics.com/store/cables-connectors/cables/cab-nbpuf-1utp-26awg/)
- What connections should I make from FathomX to the ROV’s Arduino Mega to make the Serial connection?

Thanks!!!

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<div class="post-metadata">

**Author:** ![john6](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@john6](https://discuss.bluerobotics.com/u/john6)\
**Post date:** [February 27, 2022, 2:21pm UTC](https://discuss.bluerobotics.com/t/fathom-to-arduino-serial-connection/11634/2 "2022-02-27T14:21:59Z")

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If you just want serial data, it would probably be easiest to utilize a second twisted pair in the tether and use a pair of RS485 converters to connect to the Arduinos.

If you want to use the Fathom it would probably be best to add an ethernet switch ([https://bluerobotics.com/store/comm-control-power/tether-interface/ethswitch/](https://bluerobotics.com/store/comm-control-power/tether-interface/ethswitch/)) top and bottom and use an ethernet shield on the Arduinos instead of using the serial ports.

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<div class="post-metadata">

**Author:** ![jua123](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@jua123](https://discuss.bluerobotics.com/u/jua123)\
**Post date:** [February 27, 2022, 3:23pm UTC](https://discuss.bluerobotics.com/t/fathom-to-arduino-serial-connection/11634/3 "2022-02-27T15:23:43Z")

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Thanks!!!

So it is much easier than I thought! The FATHOM board would be useful if you need video but since it is not my case, I understand that following this attached diagram and using the standard cable [https://bluerobotics.com/store/cables-connectors/cables/cab-nbpuf-4utp-26awg](https://bluerobotics.com/store/cables-connectors/cables/cab-nbpuf-4utp-26awg) / and RS485, it would only use two twisted pairs and it would already have serial communication.

 ![FullDuplexRS485](https://us1.discourse-cdn.com/flex019/uploads/bluerobotics/original/2X/4/4ff8aa88d036f7a7265b020d0175b04da8711c24.png)

Thanks!!!