DIY isolated VE.Direct interface for four devices on Venus OS — FT4232HL or four isolated FT232 modu

Got a similar dilemma on the narrowboat — running four VE.Direct devices into a Pi 4 with Venus OS and trying to figure out the cleanest solution without ending up with a rats nest of USB hubs and cheap CH340 adaptors.

Currently eyeing up two options:

Option 1 — FT4232HL breakout board
Single USB connection, four UART channels. Tidy. But galvanic isolation is trickier — you'd need to add something like ADuM1201 isolators on each channel, which starts getting fiddly if you're not handy with a soldering iron.

Option 2 — Four separate isolated FT232 modules
Something like the ones from Waveshare with built-in isolation. Plug-and-play-ish, but then you're back to needing a decent USB hub (powered, obviously — ideally something like a StarTech unit) and four separate cables.

My setup is a SmartSolar 100/50, SmartShunt, and Cerbo GX already talking nicely, but I'm adding an Orion XS and a second MPPT soon, which is why I'm revisiting this.

Main questions I can't quite nail down:

• Does Venus OS reliably enumerate four FT232 devices without udev rule faff?
• Anyone actually running the FT4232HL route with isolation added — worth the effort?
• Is galvanic isolation even strictly necessary on a 12V DC-only narrowboat/camper system, or is it more of a "belt and braces" thing?

Would love to hear from anyone who's gone down either path. Particularly interested if anyone's used Fogstar or Victron kit in a similar multi

@Jason1970 done exactly this on the motorhome using a FT4232HL breakout — single USB, four UART channels, works a treat with Venus OS once you sort the udev rules. Isolation's the bit people skip then regret; I added ADM2483 isolators on each channel, overkill maybe but no ground loop grief.

One thing worth knowing — Venus OS enumerates VE.Direct by port path not by tty name, so physical USB layout matters. With the quad chip you need to be consistent about which channel maps to which device or it'll drive you mental after a reboot.

Four separate isolated FT232 modules works but it's messy and you'll end up with a chunky USB hub anyway. The quad route is cleaner if you're handy with a soldering iron.

@Jason1970 welcome to the forum — great first post, and narrowboat installs are always an interesting challenge given the space constraints!

Worth considering the isolation side carefully before committing to either route. On my narrowboat I found that without proper galvanic isolation between VE.Direct ports you can get ground loops causing weird data corruption — particularly nasty when shore power is involved.

If you go the FT4232HL route as @SuffolkSolar suggests, you'll likely still need external isolation per channel (something like the ADuM1201 or dedicated ADUM-based modules). Four separate isolated FT232 modules is messier physically but each handles its own isolation cleanly out of the box.

What four devices are you connecting? Battery monitor, MPPT, inverter, and...? That might influence which way makes more sense practically.

@Jason1970 one thing worth flagging that nobody's mentioned yet — the isolation side matters a lot on a narrowboat specifically. You've got 12/24V DC running alongside shore power, potentially a generator, and wet bilge environments all conspiring to create nasty ground loops. Even on my motorhome I got intermittent MPPT data corruption until I added proper galvanic isolation on the VE.Direct lines.

If you go the FT4232HL route, you'll need external isolators per channel anyway — something like the ADuM1201 or a dedicated SI8642 does the job nicely. Four separate isolated FT232 modules (the ones with built-in ADuM isolation) actually work out simpler to wire even if it looks messier on paper.

Victron's own VE.Direct to USB cables are isolated, but at ~£20 each plus a decent USB hub you're looking at meaningful cost vs rolling your own properly.

@AndyRobinson raises a really good point about isolation — keen to understand more on that front actually. I'm doing a shepherd's hut build at the moment rather than a narrowboat but I've been wrestling with the same four-device VE.Direct question (MPPT, BMV, inverter, Cerbo workaround).

@SuffolkSolar did you need any level shifting on the FT4232HL or did the 3.3V UART lines talk to VE.Direct without issue? VE.Direct is nominally 5V tolerant but I've seen conflicting info online.

Also wondering whether four individual isolated FT232 modules (something like the Waveshare units) might actually be cleaner to wire despite the extra USB hub — at least then each channel is independently isolated rather than sharing isolation across the quad chip. Anyone done a direct comparison?