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I try to read out OBD-2 data from Hyundai Ioniq Electro (Version 28kWh), using a Raspberry PI and a Bluetooth ELM327 interface. Connection and data transfer works fine.

For example: sending 2105<cr><lf> gives a response (<cr> is value 0x0d = 13):
7F2112<cr>7F2112<cr>7F2112<cr>02D<cr>0:6105FFFFFFFF<cr>7F2112<cr>1:00000000001616<cr>2:161616161621FA<cr>3:26480001501616<cr>4:03E82403E80FC0<cr>5:003A0000000000<cr>6:00000000000000<cr><cr>>

The value C0 in 4:03E82403E80FC0 seems to be the State of charge (SOC) display value:
C0 -> 192 -> 192/2 % = 96%

There are some tables for decoding available (see https://github.com/JejuSoul/OBD-PIDs-for-HKMC-EVs/tree/master/Ioniq%20EV%20-%2028kWh), but how to use these tables?

For example sending 2101<cr><lf> gives the response:

02C<cr>
0:6101FFFFF800<cr>
01E<cr>
0:6101000003FF<cr>
03D<cr>
0:6101FFFFFFFF<cr>
016<cr>
0:6101FFE00000<cr>
1:0002D402CD03F0<cr>
1:0838010A015C2F<cr>
7F2112<cr>
1:B4256026480000<cr>
1:0921921A061B03<cr>
2:000582003401BD<cr>
2:0000000A002702<cr>
2:000F4816161616<cr>
2:00000000276234<cr>
3:04B84100000000<cr>
3:5B04692F180018<cr>
3:01200000000000<cr>
3:1616160016CB3F<cr>
4:00220000600000<cr>
4:00D0FF00000000<cr>
4:CB0100007A0002<cr>
5:000001F3026A02<cr>
5:5D4000025D4600<cr>
6:D2000000000000<cr>
6:00DECA0000D8E6<cr>
7:008A2FEB090002<cr>
8:0000000003E800<cr>
<cr>
>

Please note, that the line feed was added behind every carriage return (<cr>) for better readability and is not part of the original data response.

How can I decode temperature, currents, ... from these data?

Manfred Steiner
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1 Answers1

2

I have found the mistake by myself. The ELM327 description (http://elmelectronics.com/DSheets/ELM327DS.pdf) explains the AT commands in detail.

The problem on this issue was the mixing of CAN responses from multiple ECU's caused by the AT H0 command (headers off) in the initialization phase (not described in question). See also EM327DS.pdf page 44 (Multiple Responses).

When using AT H1 on startup, the responses can be decoded without problem.

Initialization (with AT H1 = headers on)

AT D\r\n
AT Z\r\n
AT L0\r\n
AT E0\r\n
AT S0\r\n
AT H1\r\n
AT SP 0\r\n

Afterwards communication with ECU's:

  1. Response on first command 0100\r\n:
SEARCHING...\r7EB06410080000001\r7EC06410080000001\r\r>
  1. Response on second command 2101\r\n:
7EE037F2112\r7ED102C6101FFFFF800\r7EA10166101FFE00000\r7EC103D6101FFFFFFFF\r7EB101E6101000003FF\r7EA2109211024062703\r7EC214626482648A3FF\r7ED2100907D87E15592\r7EB210838011D88B132\r7ED2202A1A7024C0134\r7EA2200000000546900\r7EC22C00D9E1C1B1B1B\r7EB220000000A000802\r7EA2307200000000000\r7ED23050343102000C8\r7EC231B1B1C001BB50F\r7EB233C04B8320000D0\r7EC24B5010000810002\r7ED24047400C8760017\r7EB24FF300000000000\r7ED25001401F387F46A\r7EC256AC100026CB100\r7EC2600E3C50000DE69\r7ED263F001300000000\r7EC27008CC38209015C\r7EC280000000003E800\r\r>
  1. Response on third command 2105\r\n:
7EE037F2112\r7ED037F2112\r7EA037F2112\r7EC102D6105FFFFFFFF\r7EB037F2112\r7EC2100000000001B1C\r7EC221C1B1B1B1B2648\r7EC2326480001641A1B\r7EC2403E80803E80147\r7EC25003A0000000000\r7EC2600000000000000\r\r>

Now every response starts with the id of the ECU. Take attention only to responses starting with 7EC.

Example:

Looking for battery current in amps. In the document Spreadsheet_IoniqEV_BMS_2101_2105.xls you find the battery current on:

  • response 21 for 2101: last byte = High Byte of battery current
  • response 22 for 2101: first byte = Low Byte of battery current

So look to the response of 2101\r\n and search for 7EC21 and 7EC22: You will find:

  • 7EC214626482648A3FF: take last byte for battery high value -> FF
  • 7EC22C00D9E1C1B1B1B: take first byte after 7EC22 for battery low value -> C0

The battery current value is: FFC0

This value is two complements encoded:
0xffc0 = 65472 -> 65472 - 65536 = -64 -> -6.4A

Result: the battery is charged with 6.4A

For a coding example see:
https://github.com/greenenergyprojects/obd2-gateway, file src/obd2/obd2.ts

Manfred Steiner
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