Freediag Scantool for Linux

Application Manual.

CVSID $Id: Scantool-Manual.htm,v 1.2 2003/04/20 22:43:19 rpalmeida Exp $

This manual applies to Version 0.3 of Freediag/Scantool.

OBDII Introduction: -

In the Mid 1990’s the US introduced mandated diagnostics on all vehicles sold in the USA for certain emissions related information. The idea behind this is that cars would monitor for emissions related problems and when they occur to light a “Check Engine” lamp on the dashboard and log fault information that could be then read by a Scantool. Scantools would become cheap and available to the smallest of vehicle repairers. These diagnostic protocols were grouped under the term “OBD II”.

Europe has recently introduced similar, compatible systems, which are known as EOBD (European OBD).

OBDII/EOBD requires a standardised physical connector to be present within a small distance of the vehicle’s steering wheel. OBDII allows 3 types of physical interface (ISO9141/14230, SAEJ1850 VPW and SAEJ1850-PWM) and the related software protocols that are used with those physical interfaces.

This manual assumes that you have some knowledge of vehicle systems and have probably used a scantool before.

Scantool Introduction.

This Scantool uses SAEJ1979 (ODB II) protocol on ISO9141, ISO14230, SAEJ1850 VPW and SAEJ1850-PWM interfaces depending on what hardware interface is attached to the PC. The scantool does not yet support any manufacturer specific protocols for talking to non OBDII vehicles.

It is configured by default to use a generic serial to ISO9141 converter such as those used on the VAG-COM software, It also supports smart interfaces from Multiplex Engineering and from B.Roadman for SAEJ1850 vehicles (mainly Ford and GM).

Please refer to the “supported interfaces” document to determine which interface support what protocols.

1) Building the scantool.

The scantool distribution is a source-code distribution, so you will have to configure/compile it for your Linux system. To do this, unpack the archive and in the src directory, type

./configure

make

2) Running Scantool

The Scantool should be run as SuperUser as the process has to set real-time scheduling in order to get accurate timing control under Linux. If it is run by an un-privileged user than a warning will be printed and the scantool may not work. It is extremely unlikely to work on ISO9141/ISO14230 interfaces, it may work with SAEJ1850 type interfaces where timing is not so critical..

Start the Scantool CLI by running "./Scantool", you will get a command prompt: -

.

scantool>

The scantool will read commands from a startup file called .scantoolrc in your home directory.

Many people will put the appropriate

set interface <type>

command (see section 4) in their .scantoolrc file and will just want to use the scan,and the cleardtc commands.

3) Using the Command Line Interface (CLI): -

The CLI is hierarchical, with normal commands at the top level – these commands include: -

scan start a scan
monitor loop repeatedly checking/displaying ECU values

2nd level commands, such as commands to set the address used by the scantool can be accessed as
set testerid VALUE
or by entering the set menu
set
and then using the testerid command
testerid VALUE

Note the cli prompt will change from
scantool>
to
scantool/set>

To leave that menu and return to the main menu, type
quit

Using the quit command at the main menu will end the scantool application.

All numeric values can be entered as
123 decimal 123
$27 hexadecimal 27
0x27 hexadecimal 27
012 Octal 012

The help command is available at every menu and gives you help for the commands available at that menu. Further information about a specific command can be obtained by typing help <command>.

The CLI supports shell like command line editing if supported by your Linux version.

Commands: -

The following commands are available. Other commands may be visible from the CLI but are not supported

Main Menu: -
scan Does an OBDII Scan for all parameters
monitor [english/metric] Loops requesting/displaying OBD
Mode1/2/7 results
cleardtc Clear stored Diagnostic Trouble Codes

source <filename> Read commands from <filename>

log [logfile] Basic data logging to logfile specified
stoplog Stops logging

watch [raw] Watch the K line bus and attempt to decode data

test - SUBMENU, see later, perform various tests - mostly performed
in scan process

set - SUBMENU, see later, set parameters for diagnostic functions
diag - SUBMENU, see later, extended diagnostic functions
debug - SUBMENU, see later

help [command] Help
quit Quit/Exit
exit Quit/Exit

Test Sub-Menu: -
rvi Do OBD Mode 9 requests for vehicle info (vin etc)
cms Request/Display continuously monitored system results
ncms Request/Display non continuously monitored system results
[more verbose than in scan]
readiness Do readiness tests [more verbose than in scan]

Set Sub-Menu: -
show show all item values

speed [value] show/set the speed to connect to ECU at
testerid [val] Set the source address to use
destaddr [val] Set the destination address to connect to
protocol [val] Set the protocol to use. Use protocol ? to get list
initmode [val] Set the initmode to use. Use initmode ? to get list
display [english/metric] Sets default display mode for monitor command
interface [type] Set the type of hardware interface. Use interface ? to get a list

of interface types, and refer to the supported interface document.

Diag Sub-Menu :-
connect Connect to an ECU, but do not run any tests. Uses the protocol/speed etc set,

i.e does not try multiple protocols.
sendreq Send data on the bus
sr Same

read [timeout] Read data from the bus, timeout after timeout seconds
rx Same

Debug Sub-Menu: -
show show debug levels
l0 [val] show/set layer 0 debug value
l1 [val] show/set layer 1 debug value
l2 [val] show/set layer 2 debug value
l3 [val] show/set layer 3 debug value
cli [val] show/set layer cli debug value
all [val] show/set debug values for all the layers

pids show supported PIDS/TESTs for mode 1/2/5/6/9
dumpdata show received data for mode 1/2 tests

4) Hardware Interfaces: -

Please refer to the “supported” interface document to determine which hardware interface is appropriate for your usage and which version of the interface you should purchase.

In order to use the appropriate driver for your hardware interface the appropriate “set interface XXX” command needs to be run. The default interface driver is the se9141 driver which works with most generic serial to ISO9141 interfaces. It is recommended that you put this command in your .scantoolrc file.

Andy Whittaker's OBD-II ISO9141 interface:
http://www.andywhittaker.com/ecu/obdii_hardware.htm

set interface se9141

Jeff's OBD-II ISO 9141 interface:
http://www.planetfall.com/~jeff/obdii

set interface se9141

Silicon Engines ISO 9141 interface:

http://www.siliconengines-ltd.com/products/se/9141/9141.html

set interface se9141

B.Roadman ISO9141/VPW/PWM interface:

http://www.abcwc.net/accounts/quanta/index.html

set interface br1

Multiplex Engineering VPW, PWM, and ISO 9141-2 interface:

http://www.multiplex-engineering.com/products.htm

set interface met16

Note, if you have a Multiplex Engineering interface not purchased for the freediag software, it will have a different ID to that used in the freediag project. Freediag uses ID 0x38. If you know the ID of your interface you can change the INTERFACE_ADDRESS definition in diag_l0_me.c and recompile.