I want to measure current fuel level inside my car's fuel tank using OBD2 bluetooth/USB adapter.
When i try to query that PID i got following data as "NO DATA" while at the same time i can check other PIDS like RPM and all data comes fine.
I have small python program which reads its but i am unable to get it.
import serial
#ser = serial.Serial('COM12',38400,timeout=1)
#ser.write("01 2F \r")
#speed_hex = ser.readline().split(' ')
#print speed_hex
#convert hex to decprint ("SpeedHex",speed_hex)
#speed = float(int('0x'+speed_hex[3],0))
#print ('Speed',speed,'Km/h')
ser1 = serial.Serial("COM12",38400,timeout=1)
#ser1.write("ATZ \r")
#ser1.write("ATE0 \r")
#ser1.write("ATL0 \r")
#ser1.write("ATH1 \r")
#ser1.write("ATSP 5 \r")
ser1.write("01 0C \r")
fuel_hex= ser1.readline()
print fuel_hex
#convert to hex to decprint ("FuelHex",fuel_hex)
#fuel = float(int('0x'+fuel_hex[3],0))
#print ("Fuel in Per",fuel)
Can any one suggest here how to get fuel level which is their inside in car at this current time. As i can see in my panel with bar sign.
In order to get all the available PIDs in a vehicle, you have to request the following PIDs at first exactly like you ask the rpm of the vehicle:
0x00, 0x20, 0x40, ....0x80 and so on.
For instance when you request PID 0x00 the ECU will return you 4 bytes which means if it supports PIDs from 0x01 - 0x20. Each byte has 8 bits in total of 32 bits which is exactly from PID 0x01 to PID 0x20. Now it is time to parse the data. If each bit is 1 it means the ECU will support and 0 no support. It is your duty to do some bitwise operations to translate these bits:
Also you can look out this Wikipedia link which shows in graphics!
byte 1 bit 1 : availability of PID 0x01
byte 1 bit 2 : availability of PID 0x02
byte 1 bit 3 : availability of PID ox03
....
byte 4 bit 7 : availability of PID 0x1F
byte 4 bit 8 : availability of PID 0x20 --> Here the ECU tells you if support any PIDs in next 32 PIDs. If it is 0, you do not need to check anymore!
After parsing and gathering all the supported PIDs, then you can have a roadmap to calculate or check each PIDs you want. Do not forget many of conversion rates a formulas in wikipedia is wrong due to the complexity of calculations. You have to read the ISO 15031 part 5 and do NOT forget ECU only gives you the emissions-related diagnostics and not all the data.