Interfacing with Resol VBus using Basic HTTP

I have ComfortClick interfaced to my KNX devices but I would like to also link to my Solar Controller.  The controller is a Resol Deltsol MX  http://www.resol.de/index/produktdetail/kategorie/1/id/69/sprache/en connected to the Resol DL2 Dataloger http://www.resol.de/index/produktdetail/kategorie/2/id/12/sprache/en

All Resol and compatible controllers use the VBus and their are a variety of ways to connect to it.  You can get raw VBus over TCP by telneting to port 7053 of any device on the VBus with an Ethernet interface (see here https://danielwippermann.github.io/resol-vbus/vbus-over-tcp.html) for example.  This lets you issue commands as well as read data.

Initially I am just trying to read data from the bus by using the JSON Data Download API https://danielwippermann.github.io/resol-vbus/dlx-data-download-api.html

If I connect to my device on the following URL I get a JSON formatted response

http://dl2/dlx/download/live?sessionAuthUsername=admin&sessionAuthPassword=password

I am trying to read the temperature that is available as "value" in the following snipit

        "headersets" : [
        {
                "timestamp" : 1506413326.784000,
                "packets" : [
                {
                        "header_index" : 0,
                        "timestamp" : 1506413311.424000,
                        "field_values" : [
                        {
                                "field_index" : 0,
                                "raw_value" : 22.900000,
                                "value" : "22.9"
                        },

Using the basic HTTP device with the the following settings I am able to read this Temp

The JSON token name is 

headersets[0].packets[0].field_values[0].raw_value