solo 2 dl vs. mxm, and connections

I have an old solo 1 dl, bought new in 2013. I have a SmartyCam HD.

I want to replace the solo 1 dl with something newer. The replacement must work with the SmartyCam HD.

After much searching and googleing, this is what I THINK is correct. Please correct me if I'm wrong.

1--Solo2DL and MXM are about the same, except MXM can accept 4 inputs for sensors; S2DL none.

    (I have settled on these two because above MXM it gets much more expensive, and I don't need 50         inputs).

2--OBD2 connection is poor (not much data and very slow). Car is 1999.

     So, can connect them directly to ECU via RS232 cable. (Right?)

3--If #2 is correct, any instructions available for how to connect RS232 wires to ECU?

4--Do I need an ECU bridge or data hub with S2DL or MxM?

5--Anything else I need to know? (I do know that these units are on forever backorder, but I want to be prepared).

Thanks.

Miata ECU doesn't send data via RS232. The only analog input you can have with a Solo2DL is RPM.

I believe MXM is all you need, then use the supplied cable for your analog signals and plug your SmartyCam in.

So, S2DL can only connect with an OBD2 cable or an RPM cable?

MXM cable connects to ECU via OBD2 port or wired directly to ECU?

Thanks.

Further research has yielded:

For NB, It doesn't matter what data logger is used, or what cable is used, or whether it's connected to the OBD2 port or directly to the ECU, there is very little data that can be pulled. To get additional data, sensors have to be installed, and S2DL does not accept additional sensors, MxM can accept four of them. Correct me if I'm wrong.

Correct