node-serialport: readline Hex encoding problem

Hi i have problems reading line with hex encoding

1) c0a8
2) fe534d415254434c4f5544aaaa091600010c022d2cd1c0a8
3) fe534d415254434c4f5544aaaa091600010c022d2cd1c0a8
4) fe534d415254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223afc0a8
5) fe534d415254434c4f5544aaaa0e012b01b8f036ffff000000d80bc0a8
6) fe534d415254434c4f5544aaaa091600010c022d2cd1c0a8
7) fe534d415254434c4f5544aaaa0653004178e2c0a8
8) fe534d415254434c4f5544aaaa1a150001523128312e3433293c31322d313e5b315d2a002af89ac0a8
9) fe534d415254434c4f5544aaaa1a150002523128312e3433293c31322d323e5b325d2a002ab006c0a8
10) fe534d415254434c4f5544aaaa1a150003523128312e3433293c31322d333e5b335d2a002a8872c0a8
11) fe534d415254434c4f5544aaaa1a150004523128312e3433293c31322d343e5b345d2a002a213ec0a8
12) fe534d415254434c4f5544aaaa1a150005523128312e3433293c31322d353e5b355d2a002a194ac0a8
13) fe534d415254434c4f5544aaaa1a150006523128312e3433293c31322d363e5b365d2a002a51d6c0a8
14) fe534d415254434c4f5544aaaa1a150007523128312e3433293c31322d373e5b375d2a002a69a2c0a8
15) fe534d415254434c4f5544aaaa1a150008523128312e3433293c31322d383e5b385d2a002a136fc0a8
16) fe534d415254434c4f5544aaaa1a150009523128312e3433293c31322d393e5b395d2a002a2b1bc0a8
17) fe534d415254434c4f5544aaaa1a1500
18) 523128312e3433293c31322d31303e5b31305d2ac295c0a8
19) fe534d415254434c4f5544aaaa1a15000b523128312e3433293c31322d31313e5b31315d2a9832c0a8
20) fe534d415254434c4f5544aaaa1a15000c523128312e3433293c31322d31323e5b31325d2a1060c0a8
21) fe534d415254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223afc0a8
22) fe534d415254434c4f5544aaaa0e012b01b8f036ffff000000d80bc0a8
23) fe534d415254434c4f5544aaaa091600010c022d2cd1c0a8
24) fe534d415254434c4f5544aaaa091600010c022d2cd1c0a8
25) fe534d415254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223afc0a8

first problem is line 1 and it always happen randomly
bigger problem is line 17 & 18 and ‘0a’ is mising ! The complete line is

fe534d415254434c4f5544aaaa1a15000.0a.523128312e3433293c31322d31303e5b31305d2ac295c0a8 my packets always start with fe534d415254434c4f5544aaaa please help me Thanks

About this issue

Original URL
State: closed
Created 6 years ago
Comments: 16 (9 by maintainers)

Most upvoted comments

> Buffer.from('aaaa030130')
<Buffer 61 61 61 61 30 33 30 31 33 30>

☝️ uses utf8 by default

To use HEX pass the encoding on the second argument.

> Buffer.from('aaaa030130', 'hex')
<Buffer aa aa 03 01 30>

Glad we could help!

reconbot on Oct 26, 2018

@reconbot @HipsterBrown Hi Here is what you want and my problems solved

{ port: 'c0a80afe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe534d415254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223af' }
{ parser: 'fe534d415254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223af' }
{ port: 'c0a80afe534d4152' }
{ port: '54434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ parser: 'fe534d415254434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ port: 'c0a80afe53' }
{ port: '4d415254434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe534d' }
{ port: '415254434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe53' }
{ port: '4d415254434c4f5544aaaa12012b01b8efffffff' }
{ port: '03fefefe0c2d0223af' }
{ parser: 'fe534d415254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223af' }
{ port: 'c0a80afe534d' }
{ port: '415254434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ parser: 'fe534d415254434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ port: 'c0a80afe534d' }
{ port: '415254434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe53' }
{ port: '4d415254434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe534d' }
{ port: '415254434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe534d' }
{ port: '415254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223af' }
{ parser: 'fe534d415254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223af' }
{ port: 'c0a80afe534d4152' }
{ port: '54434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ parser: 'fe534d415254434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ port: 'c0a80afe534d41' }
{ port: '5254434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe534d41' }
{ port: '5254434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe534d41' }
{ port: '5254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223' }
{ port: 'af' }
{ parser: 'fe534d415254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223af' }
{ port: 'c0a80afe534d4152' }
{ port: '54434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ port: 'c0' }
{ parser: 'fe534d415254434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ port: 'a80afe534d41' }
{ port: '5254434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe534d41' }
{ port: '5254434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe534d' }
{ port: '415254434c4f5544aaaa12012b01b8efffffff03fefefe0c' }
{ port: '2d0223af' }
{ parser: 'fe534d415254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223af' }
{ port: 'c0a80afe534d41' }
{ port: '5254434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ parser: 'fe534d415254434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ port: 'c0a80afe534d41' }
{ port: '5254434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe534d4152' }
{ port: '54434c4f5544aaaa091600010c022d2cd1' }
{ parser: 'fe534d415254434c4f5544aaaa091600010c022d2cd1' }
{ port: 'c0a80afe534d41' }
{ port: '5254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d' }
{ port: '0223af' }
{ parser: 'fe534d415254434c4f5544aaaa12012b01b8efffffff03fefefe0c2d0223af' }
{ port: 'c0a80afe534d41' }
{ port: '5254434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ parser: 'fe534d415254434c4f5544aaaa0e012b01b8f036ffff000000d80b' }
{ port: 'c0a80afe534d41' }
{ port: '5254434c4f5544aaaa0653004178e2' }
{ parser: 'fe534d415254434c4f5544aaaa0653004178e2' }
{ port: 'c0a80afe534d41' }

1 ) I found ‘0a’ “The line feed” was the responsible for parser going to next line , i changed delimiter to ‘c0a80a’ and now it perfectly works

2 )And for the error

TypeError: "delimiter" has a 0 or undefined length

when the encoding is hex , i should not use ‘\n’ , ‘\r’ , if we use ‘hex’ it works correctly

Another Question : how could i write ‘hex’ ? Is it correct? The system does not show anything ( system is SBus Home Automation System)

port.write(Buffer.from('aaaa030130'));

Thanks a lot for your helps and answers 👍

aminjoharinia on Oct 26, 2018

If you log data events of the source data and the parser we can construct a test from the output and determine if the parser is doing something wrong.


var SerialPort = require('serialport');
const Readline = require('@serialport/parser-readline')
var port = new SerialPort('/dev/ttyS0', {
baudRate:115200

});

const parser = port.pipe(new Readline({ delimiter: '\n', encoding: 'hex' }))
port.on('data', data => console.log({ port: data.toString('hex') }))
parser.on('data', data => console.log({ parser: data }))

reconbot on Oct 24, 2018