Node.js中Hex转ASCII异常？RS232秤通信数据解析问题

Hey there! I totally get how frustrating it can be when you’ve got communication working but hit a snag parsing the data. Let’s break down what’s going on with that buffer and fix the conversion issue.

First, let’s start with the raw buffer you have:

const scaleBuffer = Buffer.from([0x06, 0x02, 0x30, 0x32, 0x1b, 0x33, 0x1b, 0x31, 0x31, 0x34, 0x34, 0x35, 0x1b, 0x30, 0x30, 0x30, 0x1b, 0x30, 0x30, 0x1b, 0x30, 0x30, 0x1b, 0x30, 0x30, 0x03]);

Why the "Error" Happens (Spoiler: It’s Probably Not an Error!) #

When you convert this buffer to ASCII, you’re seeing what looks like errors because it contains control characters that are part of the RS232 protocol your scale uses:

• 0x06: ACK (acknowledge signal) – invisible in standard output
• 0x02: STX (start of text) – marks the beginning of the data frame
• 0x1b: ESC (escape character) – used to signal protocol-specific commands/segments
• 0x03: ETX (end of text) – marks the end of the data frame

These are normal parts of the scale’s communication, not conversion errors. Let’s convert it properly and extract the useful data.

Step 1: Convert Buffer to ASCII Correctly #

Use Node.js’s built-in toString('ascii') method – this won’t throw an error, but you’ll see invisible control characters in the output:

const asciiString = scaleBuffer.toString('ascii');
console.log(asciiString);
// Output will look like: 0231144500000000000
// (The weird symbols are the control characters mentioned above)

Step 2: Extract Useful Data #

If you want to get rid of the control characters and focus on the printable data, filter out non-printable ASCII bytes (0x20 to 0x7E are printable):

const printableData = scaleBuffer
  .filter(byte => byte >= 0x20 && byte <= 0x7E)
  .toString('ascii');
console.log(printableData); // Output: 023114450000000000

Step 3: Parse the Scale’s Protocol #

For more precise parsing, use the STX and ETX markers to isolate the core data frame, then split by the ESC characters to get individual segments:

// Find positions of STX (0x02) and ETX (0x03)
const stxPos = scaleBuffer.indexOf(0x02);
const etxPos = scaleBuffer.indexOf(0x03);

if (stxPos !== -1 && etxPos !== -1 && etxPos > stxPos) {
  // Extract the data between STX and ETX
  const dataFrame = scaleBuffer.slice(stxPos + 1, etxPos).toString('ascii');
  // Split by ESC character (\x1b) to get protocol segments
  const protocolSegments = dataFrame.split('\x1b');
  
  console.log('Raw data frame:', dataFrame);
  console.log('Parsed segments:', protocolSegments);
  // Output segments: ['02', '3', '11445', '000', '00', '00', '00', '00']
}

Those segments (like 11445) are likely the weight reading or other scale metrics – you’ll need to cross-reference your scale’s communication manual to know exactly what each segment represents.

内容的提问来源于stack exchange，提问作者João Moreira