question

jm0278 avatar image
jm0278 asked

Cerbo GX ESS Mode 2 Intermittent Code 2 "Connection Error"

I have a Multiplus-II, SmartSolar MPPT, with a Cerbo GX for the brains. I've written an ESS mode 2 control program that runs on a dedicated Raspberry Pi. The program queries the Cerbo on a one-minute cycle using Modbus TCP, sleeping between queries, and gets an intermittent code 2 (Connection Error) communicating with the Cerbo several times over the course of a 24-hour day.

The error has shown up at all times of day and generally lasts for 10 minutes or less. I know the Raspberry Pi is still online because that's how I access it during the error. I know the Cerbo is still online because I can see it on the router. I suspect the Cerbo is not locked up or rebooting because it still feeds data to the VRM portal while the code 2 is going on. My program has code to retry querying the Cerbo up to four times over the course of 12.5 minutes -- all the retry loop does is reissue the "read register" request, it doesn't close or open the connection.

Any ideas? All firmware is current as of this date.


cerbo gxESSModbus TCPcommunication protocol
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
lifeingalicia avatar image
lifeingalicia answered ·

Could be another unit using same IP e.g. printer waking up - phone connecting etc...

Does it show any error on the GX / Cerbo under modbus...

https://www.victronenergy.com/live/ccgx:modbustcp_faq

at the bottom is advanced error checking maybe this helps

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

jm0278 avatar image jm0278 commented ·
@Lifeingalicia It definitely isn't another device stepping on the IP address. I have a static IP address set for the printer and my router almost always reuses the same address for the same mac address.

I should add that I have seen that the Cerbo has uploaded data to the VRM portal while this error is occurring. And, I'm pretty sure I was able to "ping" the device during the error.

Another "symptom" I'll add is that I am unable to establish a Remote Console connection to the Cerbo while this is happening.

I used to work data communications; LANs, WANs, routers, bridges, etc, and am fairly convinced the cause is software within the Cerbo and not its network connectivity. I really have to wonder if there's some sort of event taking place in the Cerbo that causes a daemon or something similar to reset/restart.

0 Likes 0 ·
lifeingalicia avatar image
lifeingalicia answered ·

Only other I can think of is the connection is closed just when you hit it thus repeat requests will fail

When repeating requests try a ful blown communication or make sure


2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.