Tips and Tricks
The Tips and Tricks section is a miscellaneous page where from time to time we will
post general information about items such as OBD 2007, the Elm327 chip, notes on
particular scan tools etc.
To kick it off we will explain how you can use our new free utility tool OBD 2007
Pid Reader. These tips are generally the result of answering support issues, so
there is no formal structure to this page. If you have a particular item you would
like to share with us, please email support@glmsoftware.com.
What is OBD 2007 PidReader?
OBD 2007 Pid Reader is a free utility program from GLM Software to allow anyone
using HyperTerminal or OBD 2007’s OBD Terminal tab with an Elm327 scan tool to quickly
translate the results returned from a Service $01 request into a meaningful list
of pids (Parameter Identifiers).
You do not need to be connected to the vehicle to use OBD 2007 Pid Reader.
Many of you are scan tool enthusiasts who enjoy using Hyperterminal, and a scan
tool to communicate with the ECU(s) of your vehicle. One of the most important items
of information that is required from a vehicle's ECU is the list of pids that the
ECU supports. We know from personal experience that compiling this list can be a
tedious and error prone exercise. OBD 2007 PidReader makes this task as simple clicking
a button.
Typically an OBD scan tool user after establishing a connection with the vehicle
using HyperTerminal will send a Service $01 request and receive a response like
the following
> 0100 // Request
41 00 BF BF B9 93 // Response
The 4 bytes returned “BF BF B9 93” would then need to be translated from a master
pid list table into their meaningful parameter ids and descriptors. OBD 2007 Pid
Reader reduces this task to a simple click of a button. The following screenshot
illustrates OBD 2007 Pid reader in action.
OBD 2007 Pid Reader
For more detailed information about how OBD 2007 PidReader works, please download
this free utility from our Downloads section. After installing the program you will
find a 6 page help manaual available from the help menu explaining how a pid list
is calculated.
If you have any questions about how this tool works, please send an email to support@glmsoftware.com
What is correct procedure for establishing a connection to your vehicle with Hyperterminal?
I often see on various forums I visit, incorrect advice as to the correct way to
establish a connection to your vehicle. If you follow the advice below when using
Hyperterminal you will always get a successful connection. The only time the following
procedure will not work is when the vehicle you are trying to connect to is not
OBDII compliant.
The first command to issue is an ATZ command, which resets the Elm327 chip to its
default settings. This should then be followed by the command to set the protocol.
However if you don't know the protocol of the vehicle, which is often the case,
then you need to ask the Elm327 chip to find it for you. This is accomplished using
the command ATSP0. The zero is a special protocol number that doesn't match any
of the actual protocol numbers, but which indicates to the Elm327 chip to perform
a search of all protocols. When the correct protocol is found the familiar OK prompt
will be returned.
Then for instance you could issue a 01 00 command to establishe the list of supported
pids.
ATZ
ELM327 v1.2
ATSP0
OK
0100
41 00 BF BF B9 93
Sometimes it may be necessary to adjust the Elm Time out value using the ATST command.
After a reset, with ATZ, the default timeout is 200ms. Some older vehicle may require
a slower timeout. To really push it, you could try AT ST FF which sets the timeout
to 1000ms the maximum allowed value.
If needed, insert the ATST command before the ATSP0 in the above example.
If you get back a list of pids, then you can be sure your vehicle is OBDII
compliant.