ROV control - Page 1
Forum section: electronics / projects

author: Edwin the inductor
author_rank: Newbie
timestamp: March 05, 2020, 03:28:11 pm
content: HelloI working on a ROV (remote operating vehicle) I'm hav com to the contorol. I wonder can I use a Arduino with TX RX?the cable is 50 m or should I use rs232? and if I use rs232 how should I do it (I'm bad on programming)?grateful for help.

author: i_am_fubar
author_rank: Regular Contributor
timestamp: March 05, 2020, 07:16:44 pm
content: Depends what you need to control. If just forward backward and you have a cable, run multiple telemetry lines?

author: johankj
author_rank: Contributor
timestamp: March 06, 2020, 09:22:31 am
content: If you want to use serial communications:Keep you baud-rate low, like 9600. That is a good trade-off between speed and transmission quality.If you are using the serial-line of an arduino, that is a 3.3V or 5V line. Over 50m you may have an issue.If you use a RS232-chip (like MAX2323), the chip usually bumps the voltage up to +/- 12V. You can easily communicate over 50m at low baud rates.Have a look at the data sheet:http://www.ti.com/lit/ds/symlink/max3232.pdfYou would have to have something like an Arduino in both your top-side controller and your ROV.

author: Pack34
author_rank: Frequent Contributor
timestamp: March 09, 2020, 02:43:21 pm
content: RS485 may be your best bet. It'll handle longer cable runs than RS232

author: fcb
author_rank: Super Contributor
timestamp: March 09, 2020, 03:04:37 pm
content: As Pack34 says: RS485Good for 4KM. You can use it in half-duplex or simplex (one pair) or full duplex (two pairs). Speeds for 500M can be quite quick, easily 115K2.

author: johankj
author_rank: Contributor
timestamp: March 11, 2020, 09:10:54 pm
content: Agree, RS485 is definetivly more robust, but for 50m, I don't think it matters. Unless he needs higher baudrates?

author: james_s
author_rank: Super Contributor
timestamp: March 11, 2020, 10:39:20 pm
content: RS485 is the way to go, it's not even going to be appreciably more expensive than real RS232 with proper levels. RS485 is specifically designed for this sort of communication.

author: johankj
author_rank: Contributor
timestamp: March 12, 2020, 08:43:48 am
content: I don't disagree, but RS232 is simpler and solves his problem.

author: fcb
author_rank: Super Contributor
timestamp: March 12, 2020, 10:39:44 am
content: Quote from: johankj on March 12, 2020, 08:43:48 amHe won't be using proper EIA232 voltage levels if he has an arduino - only RS232 packet structure e.g. 8N1. The levels will be at best 5V and 0V.You could make this run many hundreds of meters at quite high data rate - if you match impedances between the launch, cable and receiver... If the ROV is battery powered then OK, if it is powered by the umbilical, then the OP needs to understand ground lift, noise, etc.. Or just use a pair of $0.50 RS485 transceiver ICs and twisted pair and be golden.

author: johankj
author_rank: Contributor
timestamp: March 12, 2020, 11:19:31 am
content: Quote from: fcb on March 12, 2020, 10:39:44 amYes, I've pointed this out, and also suggested a suitable RS232 chip.He's running 50 metres of cable, under water presumably, hence I claim doesn't matter which one he uses.

author: james_s
author_rank: Super Contributor
timestamp: March 12, 2020, 08:23:04 pm
content: Quote from: johankj on March 12, 2020, 08:43:48 amHow is it simpler? The hardware is virtually identical, actually I'd say the hardware is simpler, the level shifter IC doesn't require any charge pump capacitors. Cost is similar, cabling requirements are essentially the same, it only requires different ICs at each end.

author: johankj
author_rank: Contributor
timestamp: March 13, 2020, 06:44:29 am
content: Quote from: james_s on March 12, 2020, 08:23:04 pmBecause it is half duplex, and OP is like:Quote