ANT Forum

Hi,

I am reverse engineering the ANT+ messaging between Zwift and Tacx Neo Smart in order to create an adapter for Tacx legacy trainers.

I noticed many messages in the main data exchange use data pages between F0 and FE which are manufacturer specific stuff according to ANT+ Common Pages document.

I also noticed those messages exceed the 8 data byte prescribed by the ANT+ specifications. See example below:

[A4] [14] [4E] [2] [F0] [0] [0] [0] [0] [0] [0] [0] [E0] [FB] [4D] [11] [5] [10] [0] [68] [0] [AD] [DF] [44]
[A4] [14] [4E] [2] [FB] [0] [3] [2] [0] [4] [2] [0] [E0] [FB] [4D] [11] [5] [10] [0] [68] [0] [AC] [FF] [69]

Questions:

1- Where can I find the data page specifications for those F0-FE messages ?

2- What is page 1B below? It's in the range of ANT+ standard messages but I cannot find it in the specs.
[A4] [14] [4E] [0] [1B] [EE] [5B] [0] [F8] [EF] [D4] [0] [E0] [EB] [26] [79] [1] [10] [0] [68] [0] [22] [8D] [11]

3- Just like page 1B, page 10 below is longer than the 8 data bytes described in the FE-C specification. Where can I find the meaning of those extra bytes? (interrestingly enough the first 8 bytes match the spec)
[A4] [14] [4E] [1] [10] [23] [FF] [0] [19] [9F] [0] [0] [E0] [EB] [26] [0B] [5] [10] [0] [68] [0] [D0] [9B] [A5]

Thanks !
     

Hi LFrigon,

I'm going to answer your questions out of order.

1. Pages in the manufacturer specific page range are defined on a per manufacturer basis. You'll have to contact Tacx to determine what the messages mean.

3. What you are seeing is extended messaging. Please read section 7.1 of the ANT Message Protocol and Usage Document to better understand the contents of the message beyond the 8 byte payload.

2. The messages on channel 0 are actually ANT+ SPD&CAD; messages.
[A4] [14] [4E] [0] [1B] [EE] [5B] [0] [F8] [EF] [D4] [0] [E0] [EB] [26] [79] [1] [10] [0] [68] [0] [22] [8D] [11]
The bolded byte above describes the Device Type. ANT+ defines Device Type 0x79 to mean ANT+ SPD&CAD;. Please read the ANT+ Speed and Cadence Profile to better understand this message.

BK