Freediag
Version 0.3
Supported
Hardware Interfaces.
CVSID $Id: Supported-Interfaces.htm,v 1.5 2003/04/20 22:43:19 rpalmeida Exp $
This manual
applies to Version 0.3 of Freediag
Electrical
Interface Types.
There are
various common hardware interfaces used for diagnostic interfaces to vehicle
electronic control units (ecus). Most manufacturers use one or two such
interfaces for all systems on a vehicle. These include: -
ISO9141
ISO14230
SAEJ1850-VPW
SAEJ1850-PWM
CAN
ISO9141 and
ISO14230 are essentially compatible at an electrical level (with the exception
that the latter will work on 24 volt
vehicles).
The freediag
protocol stack supports the above list with the exception of the CAN. The US
OBDII standard and the European EOBD standard for communicating with emissions
related ECUs do not mandate CAN support.
The ISO
protocols are generally used by European Vehicles, and the two SAEJ1850 types
by Ford and GM.
At a
software level, ISO14230 is a vastly extended ISO9141-2 protocol that supports
much longer data frames and much quicker communications startup with the ECU.
Further
information can be obtained from: -
ISO: http://www.iso.ch
SAE: http://www.sae.org
Freediag
Supported Interfaces.
Freediag
contains various drivers for different adapters that connect the PC serial port
to a vehicle. Certain interfaces support more protocol types than have been
implemented/tested within a driver, and some interfaces need to be ordered with
special attributes (such as their address) to work without recompiling the
freediag software library..
1) Andy Whittaker's OBD-II ISO9141
interface:
http://www.andywhittaker.com/ecu/obdii_hardware.htm
Freediag Driver: SE9141
This is a generic serial to ISO9141 interface available in small
quantities at a sensible price from Andy Whittaker in the UK
2) Jeff's OBD-II ISO 9141 interface:
http://www.planetfall.com/~jeff/obdii
Freediag Driver: SE9141
This site shows you how to build a generic serial to ISO9141
interface.
3) Silicon Engines ISO 9141 interface:
http://www.siliconengines-ltd.com/products/se/9141/9141.html
Freediag Driver: SE9141
This is a commercially available generic serial to ISO9141
interface. It is supplied in a robust box with lots of lights. This interface
was used to develop the first bits of the freediag project. It is functionally
the same as the above two interfaces (with the exception of all the lights and
the box)
4) B.Roadman ISO9141/VPW/PWM interface:
http://www.abcwc.net/accounts/quanta/index.html
Freediag Driver: BR1
Another commercially available interface, we haven’t yet tested
the ISO9141 side of the interface, and it does not support ISO14230. Future versions
will support ISO14230 and we used this interface to develop the J1850-VPW/PWM
support in Freediag. Thanks to B. Roadman for the donation of hardware to the
project.
5) Multiplex Engineering VPW, PWM, and ISO 9141-2 interface:
http://www.multiplex-engineering.com/products.htm
Freediag Driver: MET16
When ordering this interface you must order a T16 type interface.
Multiplex Engineering produce two varieties of the T16 interface: -
T16-002.
opto-isolated interface that requires power from the PC’s serial port and uses
a straight through male-female DB9 cable.
T16-003.
Non-opto isolated interface, uses a null-modem female-female DB9 cable, doesn’t
require (much) power from the PC.
Many PC’s do not provide enough power to drive the T16-002
interface and thus errors will occur (and “checksum error” messages will be
printed by the freediag software). As the T16-003 has no opto-isolation there
is a slight risk of damage to the PC. According to the manufacturer the risk is
low and is negligible unless the vehicle is connected to a battery charger.
When ordering an interface an interface that operates at 19200
baud and uses address 0x38 should be specified, or simple modifications to
diag_l0_me.c and recompilation will be needed.
The T16-002 interface was used to develop support for smart
interfaces in freediag, it worked on a modern Sony Laptop but not on various
branded PCs tested.
Compatibility
Matrix
Interface |
ISO9141 |
ISO14230 * |
J1850-VPW |
J1850-PWM |
CAN |
Andy |
YES |
YES |
No |
No |
No |
Jeff |
YES |
YES |
No |
No |
No |
Silicon
Engines |
YES |
YES |
No |
No |
No |
B Roadman |
YES
(1) |
No(3) |
YES
(1) |
YES |
No |
Multiplex |
YES |
YES
(2) |
YES
(1) |
YES
(1) |
No |
* Support
for ISO14230 software layer, not for 24V vehicles.
1 Should
work, but not tested
2 Will work
in some applications [including OBDII] but h/w doesn’t support all of the
features of the protocol.
3 Support
planned by h/w manufacturer.