Optolink Duo Block

This project was created to have local access to the viessmann heating system to monitor and control and have the vitoconnect still working. In OpenV Wiki and it's issue section can be found a lot of information and links to other interesting Projects. But all of them either only monitor the communication between the heating system and the vitoconnect or the directly communicate with the heating system. Therefore, this project was started to control the connection of the vitoconnect from the monitoring pc.

The basic idea of this project was taken from USB_Duo-Sniffer. I extended the circuit to be able to block the vitoconnect to be able to send read or write commands directly to the heating system.

Finally, the heatpump should be integrated into my OpenHAB installation to monitor the status and control it depending on PV power and weather situation. Due to the reason I'm not very familiar with Java (and the long delay of PR reviews) I wrote the Software with Python and reused a simple HTTP Server from another Project to integrate it into OpenHABs via the http plugin. So this Project can be also reused in other context.

Project

Folder	Content
Datasheet	Datasheets of used components
PCB	Schematic and PCP design. Created with KiCad
Pictures	Pictures of the Optolink Duo Block
Simulation	Electrical Simulation with LTSpice
Software	Software to monitor and read/write written in Python.

Hardware

The schematic from USB_Duo-Sniffer was reused and extended in a way that with the DTR Pin of the sniffer PC the Tx as well the Rx from the Vitoconnect can be blocked. In block mode read and write messages can be sent directly to the heating system. In unblock mode the vitoconnect can communicate and the communication can be monitored.

The IR PCB was created in a similar way you can find it in OpenV Wiki as well. To fit it exact inside the cover, I simply put some tape around it and filled up the backside with hot glue, that it has nearby the same size as the original.

The circuit was soldered with TH components. And placed into an additional box. The advantage of this hardware solution over a proxy solution is that the vitoconnect can work as long the pc is not connected or the DTR pin is low.

Software

The vito_monitor_ctrl is the basic lib (it can be reused in other applications or projects) what provides the VitocalHandler class. This class factor the whole thing and provides methods to read and write data points.

Basically there is the VitoDatahandler Interface with its two implementation, for monitoring the vitoconnect and the direct read / write access. To not direct deepened on any hardware there is the OptolinkMAC to abstract them. An implementation for the OptolinkDuoBlock as well as a Dummy for testing without hardware exists. Also a implementation for the Proxy solution was created, but never tested or used.

Configuration

Data point to be read and write need to be configured either statically via value_config.py or you can set the dict during runtime. This dict contains the data point names as key and a parameter dict with fixed names.

"Aussentemperatur": { "address": 0x1234, "unit": "UT", "access": 1 , "description": "anyting, currently unused", "data_bytes": 4 }

Key	Info
address	Address of data point
unit	Unit to convert data, see vito_data_handler.py
data_bytes	Number of bytes to read / write independent from unit
access	Access type: MONITOR = 0x01, READOUT = 0x02, WRITE = 0x04 or any and combination
description	Any description, currently not used

Applications

• cmd_line_main.py: This application provides a simple shell for testing

  • press Enter to print out the current values
  • w <data_point_name> <value> to write a data point
  • exit to close

• http_server_main.py: http server to be accessed from any other tools

  • it simply can be tested with curl localhost:8006 | jq -C
  • GET http://localhost:8006 or http://localhost:8006/getstatus/ a json object with all current values and system status is provided
  • POST http://localhost:8006/set/vito/<data_point_name> to write the data, the value need to be provided as a plain test
  • POST http://localhost:8006/set/vito/configuration to set the config. It needs to be provided as a json object