Innovate Motorsports OT-2 SDK - Manual (Page 14)

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The last piece of information that we generally care about is the packet type (remember,
we have two):
Word Bit
15 Bit
14 Bit
13 Bit
12 Bit
11 Bit
10 Bit
9 Bit
8 Bit
7 Bit
6 Bit
5 Bit
4 Bit
3 Bit
3 Bit
1 Bit
0
0 1 R 1 D/S HF X 1 B7 1 B6 B5 B4 B3 B2 B1 B0
This is all handled by bit 12. A 1 indicates that it is a DATA packet, a 0 indicates that it is
a RESPONSE packet.
This leaves three other bits:
Word Bit
15 Bit
14 Bit
13 Bit
12 Bit
11 Bit
10 Bit
9 Bit
8 Bit
7 Bit
6 Bit
5 Bit
4 Bit
3 Bit
3 Bit
1 Bit
0
0 1 R 1 D/S HF X 1 B7 1 B6 B5 B4 B3 B2 B1 B0
Of these, only bit 14 might be of interest. It indicates that someone in the chain is
recording. This is how our gauges know when to blink the ‘recording’ light. Bits 10 and
11 should be ignored.
Now that we can sync to the stream and grab packets, let’s look at what is inside them.
Data Packets
In discussing the basic MTS scheme, we referred a lot to ‘devices’, but when analyzing a
data packet, it is much easier to think in terms of what we commonly refer to as
‘channels’. A channel would be a single sensor reading.
Devices can add more than one channel to the data packet (though the firmware in many
of the devices, and our LogWorks software assumes that the total count of channels in the
packet will not exceed 32). But, while an LC-1 adds 1 channel, an LMA-3 adds 5, an OT-
1b/2 adds from 1-16, and an LM-2 can add up to a whopping 23, the channels added will
always be one of three types:
• An Aux Channel
• A ‘new’ lambda/AFR channel
• An ‘old’ (LM-1) lambda/AFR channel
Aux Channels
An Aux Channel is the simplest, as we can see from the Serial 2 Specification:
Word Bit
15 Bit
14 Bit
13 Bit
12 Bit
11 Bit
10 Bit
9 Bit
8 Bit
7 Bit
6 Bit
5 Bit
4 Bit
3 Bit
3 Bit
1 Bit
0
N 0 0 D12 D11 D10 D9 D8 D7 0 D6 D5 D3 D3 D2 D1 D0