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Author Topic: Pylontech US2000 RS485 communication results in ALM  (Read 1798 times)
Caesium
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« on: August 31, 2019, 08:05:19 PM »

Hello all Smiley

I have a stack of Pylontech US2000+ that are attached to a LuxPower LXP3600ACS inverter. They're only a couple of weeks old, and mostly it all seems to be working as it should.

I've been exploring communicating with the battery stack over RS232 and RS485. I have all the protocol documentation etc and have working communications over RS232 at 1200bps - I can query analog data and get replies back, all well and good.

The problems start when I try to send the same data over RS485, which I'm trying to do because it's a lot faster (RS485 can work at 115200bps on these units). As soon as I send a single communication to the master battery, its red ALM light comes on. Curiously, I do get the proper reply I'm expecting, so it is working apart from the ALM light!

Few things to note..

The ALM light doesn't seem to affect operation, the battery still seems to operate as normal, with the exeption that it has a red light on, and the RS485 alarm data output is full of "cell under voltage" alarms.

The ALM light is only on when discharging. When charging, it goes off. When discharging again, it comes back on.

Resetting the master via the "SW" button makes the ALM go away until I send RS485 communications again.

I'm scratching my head for ideas here - any idea what I might be doing wrong? I'm especially confused that the communication does actually work, just seems to trigger this alarm! And I don't want a red ALM light on my battery, whether its affecting operation or not Smiley

Thanks for any ideas Smiley
« Last Edit: August 31, 2019, 08:09:07 PM by Caesium » Logged

3.99kWp Solar PV :: LXP3600ACS + 14.4kWh Pylontech US2000
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pantsmachine
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« Reply #1 on: September 01, 2019, 08:33:14 AM »

What distance are you running your cable over? Maybe drop your comm rate down to 9600?
« Last Edit: September 01, 2019, 09:05:56 AM by pantsmachine » Logged

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Caesium
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« Reply #2 on: September 01, 2019, 10:41:41 AM »

That's a good shout - my cable is a 2m cat5e that I cut one end off and wired the appropriate cables (GND green/white (pin 3), A orange (pin 1), B orange/white (pin 2)) into a £5 RS485 adapter off Amazon (uses CP2102 chip, pretty ubiquitous).

It doesn't need to be anywhere near that long so I'll chop the cable down to a few cm and rewire it and try again. If I get the same result I'll try 9600 baud - I think I just need to change DIP1 to "1" to do that and restart the battery..

Thanks for the reply, appreciated Smiley
« Last Edit: September 01, 2019, 10:51:45 AM by Caesium » Logged

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nowty
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« Reply #3 on: September 01, 2019, 10:47:42 AM »

Hey Caesium

I would love to communicate to my stack of Pylontech's.

Where do I find out about the protocol documention ?
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Caesium
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« Reply #4 on: September 01, 2019, 10:54:00 AM »

Hi nowty,

The best source of information I've found is, oddly enough, a German forum! This post has all the links I've been using: https://www.photovoltaikforum.com/thread/130061-pylontech-us2000b-daten-protokolle-programme/

You want "PYLON LFP Battery communication protocol - RS232 V2.8 20161216.pdf" (the RS485 one is much the same, the protocol is the same over both connections).

https://www.photovoltaikforum.com/thread/118958-pylontech-us2000b-daten-über-konsole-rs232-auslesen/?pageNo=1 also has a wealth of information, I spent a fun evening trawling through that via Google Translate Smiley

In case you're interested, I started writing some Ruby to implement the Pylontech protocol, this is what I'm currently using: https://github.com/celsworth/lxp-pylon-utils

It's all terminal based though as I'm quite old-school Smiley I knocked up a little terminal-based monitor that looks like this:



And because I'm a numbers freak, I graph the cell voltages and stuff in Munin:

« Last Edit: September 01, 2019, 11:10:47 AM by Caesium » Logged

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pantsmachine
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« Reply #5 on: September 01, 2019, 03:53:33 PM »

All dips on my us2000b's are in down position.
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HUGE insulation depth.
5.12 kw PV system with Solar edge.
4.8 kw Pylon tech battery storage.
All Low energy bulbs.
Solar I boost charging 210 ltr OSO system tank.
Balanced & zoned CH wet system & Hive 2
Wood fired thermosiphon cedar hot tub.
Masanobu Fukuoka inspired veg garden & fruit trees
Caesium
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« Reply #6 on: September 02, 2019, 01:50:47 PM »

Yeah, mine were too.

Unfortunately no success with a shorter RS485 cable - same result. And the same at 9600 baud after flipping the first DIP switch up. So I'm at a bit of a loss now really, I've gone back to serial for now as it does the job, just a bit more slowly.

pantsmachine are you communicating with your Pylons over RS485? What software are you using? Perhaps if I try some off-the-shelf software and it works, it at least isolates it to my code rather than my hardware, but I'm very confused that I do get replies back with the correct data.

It couldn't be that I have A/B inverted because then it wouldn't work at all right?
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3.99kWp Solar PV :: LXP3600ACS + 14.4kWh Pylontech US2000
LXP & Pylontech Ruby Comms Library
pantsmachine
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« Reply #7 on: September 02, 2019, 02:18:05 PM »

Comes software is thru the Goodwe charge controller and batteries. Beyond that I have not investigated.
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HUGE insulation depth.
5.12 kw PV system with Solar edge.
4.8 kw Pylon tech battery storage.
All Low energy bulbs.
Solar I boost charging 210 ltr OSO system tank.
Balanced & zoned CH wet system & Hive 2
Wood fired thermosiphon cedar hot tub.
Masanobu Fukuoka inspired veg garden & fruit trees
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