Binary and Hex Tables and Illustrations

Powers of 2 and 16:

diag​.​net/file/f4gdqshi8… ​

Conversion Table:

diag​.​net/file/f2i8jdvrf… ​

Inverse Conversion Table: follow link

Notation:

diag​.​net/file/f4fz8cvot… ​

Convert hex, binary, decimal; signed and unsigned, Online:

onlinetoolz​.​net/computers

Example of Binary to Decimal conversion:

diag​.​net/file/f1zumawux… ​

Example of Hex to Decimal conversion:

diag​.​net/file/f628nk9g9… ​

Example of Byte-by-Byte Hex to Decimal conversion (for two-byte, big endian number):

diag​.​net/file/f61v7qa9u… ​

Signed Integers: 2's complement for 16-bit data:

diag​.​net/file/f3wy3t5b8… ​

Standard OBD-II PIDs:

en​.​wikipedia​.​org/wiki/OBD-II_PI…

Note on the first byte of OBD request and response:

Request: mode $01 to $0A

Response: to indicate valid response, replace the first ‘0’ in the mode with ‘4’, or, equivalently, set to $40 + mode.

Example: for mode $01, calculate $40+$01 = 64 (decimal) + 1 (decimal) = 65 (decimal) = $41

J1979 DA Apr 2021:

sae​.​org/standards/cont…

J1979 DA Apr2002 public reference:

law​.​resource​.​org/pub/us/cfr/ibr…​.​pdf

Standard ASCII:

diag​.​net/file/f49kui5kr… ​

Extended ASCII:

diag​.​net/file/f4osflkbr… ​

Most/Least Significant Bits:

diag​.​net/file/f13h1h4z5… ​

Byte Endianness:

diag​.​net/file/f779oksf1… ​

Example of Canonical Hex + ASCII Display:

diag​.​net/file/f4whdt8wt… ​

Online Canonical Hex + ASCII Display: hex-works​.​com/eng

Raw Mode 1 and 6 data, ELM327 interface for Subaru EJ25:

>atz

ELM327 v1.3a

>atrv 12.4V

>atsp0 OK

>0100 SEARCHING... 41 00 BE 3F E8 13

>010c 41 0C 00 00

>010c 41 0C 0E 96

>0600 46 00 C0 00 00 01

>063d 00A  0: 46 3D 98 FE 00 69  1: 80 00 0D 8A 00 00 00

>0641 00A  0: 46 41 9B 14 00 1F  1: …

>0671 052  0: 46 71 9E 17 27 12  1: 00 00 29 AD 71 9F 0B  2: …  3: A1 0B …  4: 32 71 B0 17 06 9A 00  5: 5D FF FF 71 B5 0B 01  6: 27 00 31 FF FF 71 B6  7: 0B … FF FF  8: 71 B8 0B 03 7E 00 00  9: 32 C8 71 B9 31 0A 62  A: … BA 31  B: 0B A…

Mode $06 response format in ELM 327 (received over CAN bus):

46 [ 1-byte MID, 1-byte TID, 1-byte SID, 2-byte Measurement, 2-byte Minimum, 2-byte Maximum]

• MID – look up in SI
• TID – look up in SI
• SID – look up in J1979 DA, Appendix E (pp. 78-94, see link above)
  • determine signed or unsigned
  • determine scale
  • determine offset

Practice questions for Module 1:

1. In one episode of animated science fiction sitcom Futurama, robot Bender runs away when binary number … is shown reflected in a mirror of a haunted castle. Why is that?
2. If PCM replied 41 00 BE 3F E8 13 to ELM327 command 0100, is Coolant Temperature PID available?
3. What is ELM327 command to show Coolant Temperature PID?
4. If the actual coolant temperature is 76 deg Celsius, what do you expect PCM's reply to the previous command be?

Notes for M…

Practice questions for Module 2:

1. Interpret the following hex numbers as 16-bit signed (2's complement) integers:
   1. FFFFh
   2. 8000h
   3. 7FFFh
   4. F000h
2. Which 16-bit hex number, if interpreted as 2's complement, corresponds to -10 (decimal)?
3. Which 8-bit hex number, if interpreted as 2's complement, corresponds to -10 (decimal)?
4. For commands discussed during the presentation, reproduce values seen on the scantool (31 Ohm for command 0641, and 0.11 inH20 for command 063d).
5. For response to command 0671 (see above), determine TIDs, SIDs, Measurements, Minimums, Maximums. Are all measurements within valid ranges?

Notes for M…