I am running CODESYS 188.8.131.52 and Raspberry PI 184.108.40.206.
The demo application shows the same error.
I am not using the UniPian Image, but the official Raspian Stretch operating system with fixed ip adress (dhcpd), W1 disabled, OWFS running and TCP modbus overlay for UniPi installed.(https://github.com/UniPiTechnology/neuron-tcp-modbus-overlay)
My idea was to build a combined alarm clock with internet radio (squeezelite) and light alarm clock (codesys controlled dimmer over pwm). For easier setup of OWFS and squeezelite I would prefer to stay with the official Raspian installation instead of UniPian.
Could you please provide the correct modbus configuration steps on Raspian needed for having access to the device?