Is your system fully updated?
Yes - just done a full system update and get the same error 
Hi. Some time ago I did this. I remember it being a PITA when I did it.
Tbh with all my experience now. I can help you muddle way through the modbus stuff but the best way to parse data from your victron system is via mqtt
Download this and install of your pc.
Then connect to your venus device and take a look at which topics you wish to pull out.
Then use the venus os large image with node red and you can pull the topics out using the installed victron nodes or via mqtt topics and ping them straight into emon device piece of cake.
Its easy, robust and reliable.
Cheers
Gareth
Thanks Gareth - I came to that conclusion too, but I’m not running Node Red, and am having problems with that too! See here:
Could you do a quick sketch of of your system please? Inverter/charger, battery, bms, gx or venus device and comms?
Hi John.
Perfect. Can see what your trying to do now.
If you going into your cerbo. Go to setting and scrol down do youhave venus OS large features? Like this. If so then enable node red.
Then say you ip adress of your cerbo is 192.168.0.2.
Open chrome or internet explorer and go to 192.168.0.2:1880.
Then ill show you how to do the rest.
Im pretty sure cerbo gx has the venus os large features as standard now.
Cheers
Amazing! Yep - got that up and running and I’m on the Node-red webpage
Hey Gareth - just wanted to let you know that it’s all up and running now and working perfectly. Many thanks for your help.
John.
Hi John.
Glad you got it sorted 