node.js implementation of chunking a CAN response into ISO-TP frames

isotp-frames.js

const FIRST_FRAME_PCI_BYTE = 0x01
const CONSECUTIVE_FRAME_PCI_BYTE = 0x02
const FIRST_FRAME_DATA_LENGTH = 5
const CONSECUTIVE_FRAME_DATA_LENGTH = 7
const PADDING_BYTE = 0xAA

const buildFirstFrame = (responseSid, data) => {
  const responseLength = data.length + 1 // add a byte for response SID
  const firstFrameData = data.slice(0, FIRST_FRAME_DATA_LENGTH)
  const firstFrameHeader = Buffer.from([
    (FIRST_FRAME_PCI_BYTE << 4) ^ (responseLength >> 8),
    responseLength & 0xFF,
    responseSid
  ])
  return Buffer.concat([
    firstFrameHeader, 
    firstFrameData
  ])
}

const buildConsecutiveFrame = (consecutiveFrameCounter, remainingData) => {
  let frameData = remainingData.slice(0, CONSECUTIVE_FRAME_DATA_LENGTH)
  // Pad last frame
  if (frameData.length < CONSECUTIVE_FRAME_DATA_LENGTH) {
    const paddingLength = 7 - frameData.length
    let padding = Buffer.from(new Array(paddingLength).fill(PADDING_BYTE))
    frameData = Buffer.concat([frameData, padding])
  }
  const consecutiveFrameHeader = Buffer.from([
    (CONSECUTIVE_FRAME_PCI_BYTE << 4) ^ consecutiveFrameCounter
  ])
  return Buffer.concat([
    consecutiveFrameHeader, 
    frameData
  ])
}

const buildIsoTpFrames = (responseSid, data) => {
  const frames = []
  frames.push(buildFirstFrame(responseSid, data))
  let remainingData = data.slice(FIRST_FRAME_DATA_LENGTH)
  const numConsecutiveFrames = Math.ceil(remainingData.length / CONSECUTIVE_FRAME_DATA_LENGTH)
  let consecutiveFrameCounter = 1
  for (let i = 0; i < numConsecutiveFrames; ++i) {
    frames.push(buildConsecutiveFrame(consecutiveFrameCounter, remainingData))
    consecutiveFrameCounter += 1
    // Wrap consecutive frame counter
    if (consecutiveFrameCounter === 10) {
      consecutiveFrameCounter = 0
    }
    remainingData = remainingData.slice(CONSECUTIVE_FRAME_DATA_LENGTH)
  }
  return frames
}

const vin = 'WDDZF8KB1KA539167'
const vinDataIdentifier = 0xF190
const readDataResponse = Buffer.concat([
  Buffer.from([vinDataIdentifier >> 8, vinDataIdentifier & 0xFF]), 
  Buffer.from(vin)
])
buildIsoTpFrames(0x62, readDataResponse)

> buildIsoTpFrames(0x62, readDataResponse)
[ <Buffer 10 14 62 f1 90 57 44 44>,
  <Buffer 21 5a 46 38 4b 42 31 4b>,
  <Buffer 22 41 35 33 39 31 36 37> ]