Innovate Motorsports OT-2 SDK - Manual (Page 9)

9
MTS Basics (or “Serial 2 revisited”)
Regardless of how you physically connect to an OT-1B/2, its default behavior is to
continuously send a stream of MTS data packets. We often refer to this as “in band”
communication. This is also the only way to get information from any other MTS devices
chained to the OT-1b/2, so some review of the Serial 2 protocol is in order. This protocol
is covered in the verbosely named “Innovate Serial Protocol 2 (ISP2) specification
(preliminary)”. That document, as well as the only slightly more tersely named “Serial2
Protocol Supplement” are possibly worth reading (simply email
support@innovate-
tech.com and request them). But they should be taken with a grain of salt. Some features
are not implemented in all devices, and the OT-1b/2, when accessed via USB/Wi-Fi,
‘breaks’ a couple of the documented rules (which were written with serial port
communication in mind).
The following, combined with the source samples will, hopefully, give you most, if not
all, the information typically required.
Basic Scheme
The basic scheme of MTS is not too complicated. With the exception of the host (that’s
generally you!), all devices have two serial ports. The “Serial IN” is for talking to devices
earlier in the chain. The “Serial OUT” is for talking to devices later in the chain (or, if it
is the last device, the host). Even though the terms, “IN” and “OUT” imply a direction, it
is important to understand that each is a full duplex RS-232 port that the devices use to
talk to each other. Even if you are communicating with the device via USB or Wi-Fi you
are, in an MTS sense, ‘talking’ to the “Serial OUT” port of what is, from your point of
view, the last device in the chain. Examine this simple (and reasonably common) setup:
The user has two LC-1 wideband controllers, one for each ‘bank’ in a large engine, an
OT-2 for obtaining some basic information from the vehicle’s ECU (like RPM), and one
of our gauges for monitoring air fuel measurements from the LC-1’s in real time.