Pulling data from ELM327

Question

am developing an application where I can get data from ELM327 and display it on an android device.But I have a doubt,the ELM327 is not controllable,I mean it cant keep sending data automatically to the android device,so how would I be able to pull data from the ELM327.I am really stuck here.So help would be appreciated.Thank you!

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Can anyone help me with the type of commands I have to use in android to get responses from ELM 327?How would I only receive speed and rpm?How can I read that data and display it on the android device?

Answer 1

The ELM device is a command/response device which requires you to send a command in order for the ELM to process it, communicate with the ECU system, then format and deliver the response back to you. You won't get unsolicited messages (responses) from an ELM327 chip except on power up when the signature is sent, or unless you set the device into a monitor mode.