How to send more than 8 byte message in a single frame using ELM327 device in KWP2000 protocol

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I tried sending a Higher payload data frame (containing more than 8 bytes) in KWP2000 protocol but I'm getting '?' response fron the ELM327 device. In CAN this can be achieved by using Flow control and sending the data in multiple lines seperately one-by-one.......my question is, is there any way of doing the same in KWP2000?

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DrMickeyLauer On

In general, sending multiframe payloads is not supported by plain ELM327 devices. Although with some crude combinations of ATR0 and ATR1 or alternatively appending 0 and 1 to your frames to distinguish whether you want a response or not, you could do it in theory, but it's pretty unreliable on most adapters.

There are – however – several ELM327-compatible adapters (notably those based on the STN11xx and STN22xx chipsets) which have support for builtin ISOTP (if that's what you need) transmission with payloads up to the ISOTP maximum of 4095 bytes.