How to communicate with OBD-II device

Question

There is OBD-II device like http://www.rczd.com/c/2015/Car_Diagnostic_Tools_0223/41193.html this device provider does not have its web page or documentation source

Answer 1

If your device is compatible with the ELM327 you can use multiple PID requests but only if adapter is connected to the vehicle with CAN protocol. So it would work only with a subset of vehicles because not all vehicles support CAN.

Popular scan tools simply sends sequential requests. Maximum throughput you can gain with this approach is about 30-40 rps.

I don't know how freematics dongle works but I can see it has some SD card mounted - maybe it gives only emulation of parallelism and internally every request is sent sequentially?

If you are searching for reliable Java library for connecting to OBD II device I would recommend you https://github.com/pires/obd-java-api . You can also take a look at my library - https://github.com/devesion/java-obd-adapter