Gryphon Simple Gateway
1 Introduction
The Gryphon's simple gateway program is configured by
creating one or more files in the /gryphon/gate/ directory.
The Gryphon's LCD and front panel push buttons can be used
to select which of the multiple configuration files to use. The same
interface can be used to cause the gateway program to run or not run
when the Gryphon is powered up.
2 Configuration File Layout
The order of the entries is not important. Entries consist of a label
(which is case sensitive), zero or more spaces, an equal sign, zero
or more spaces and a value. Order is observed by numbers appended
to the labels. Blank lines and lines beginning with # are
ignored. There are several configuration files shipped with the Gryphon
Simple Gateway which may be used as examples if you need to create
your own.
2.1 Logical channels
A logical channel has an input and an output channel and one or more
rules that determine which messages are to be copied from its input
to its output. input and output labels are
used to define logical channels. A number (starting with 1) is appended
to both labels to specify which logical channel is being specified.
The following configures a single logical channel that reads from
the first CAN channel and writes to the second CAN channel.
input1 = can1
output1 = can2
If you want to pass messages passed in both directions, two logical
channels need to be defined as shown below:
input1 = can1
input2 = can2
output1 = can2
output2 = can1
As can be seen, relative channel numbers for each type of card are
used. Channel can1 may be channel 1 or 2 or some other channel
number depending upon the cards that are present in the Gryphon.
Valid card types are as follows:
can
j1850
kwp2000
ford_ubp
chrysler_sci
chrysler_c2d
2.2 Message selection
Message selection is based on the message header. The simple gateway
allows the message header to be changed from the input channel to
the output channel for one or more header values if desired. Header
values are specified as idn where n is a sequential number
starting with 1. The id values are associated with a logical
input by appending them to a logical channel with an underscore character.
The following defines that a message arriving on input 1 with an ID
code (header) of 18FE DA03 be sent out on output 1 with an ID code
(header) of 0250. (The data field of the message is not changed between
the input and output.)
input1_id1 = 18FE DA03
output1_id1 = 0250
To specify that all of the messages from the input are to be passed
to the output without any changes, an id value of all
is used. The following specifies that all of the messages coming in
on input 1 should be sent out on output 1.
input1_id1 = all
output1_id1 = all
By using one or more of the first type and one of the second, the
specified messages will be changed as configured while the remaining
messages are passed intact. Incoming messages are searched sequentially
starting with id1 until a match is found. all matches
everything so that if input1_id3 = all is present in the
configuration file, input1_id4 and above are ignored.
2.3 Channel speed
The default bit rate for CAN channels on the Gryphon is 500,000 bps
using 40 and 3a for btr0 and btr1
respectively. The bit rate for the first two CAN channels may be changed
to 125,000, for example, by using the following lines, assuming that
input1 has been set to can1 and that output1
has been set to can2
input1_btr0 = 03
input1_btr1 = 1C
output1_btr0 = 03
output1_btr1 = 1C
2.4 Automatic initialization
Under normal circumstances a Bus Off event for a CAN bus indicates
a serious problem that needs to be solved before proceeding. An occasional
Bus Off event may be expected if the CAN bus is disrupted in
the course of testing. This may be caused by electrical/RF interference,
by mechanically disrupting the bus, by removing or powering down the
only other device on the bus or by some other factor. Once a Bus
Off event is reported on a transmitting channel, no more messages
can be transmitted on that channel until it is initialized. The two
entries described below allow a set of rules to be defined that control
when an Initialize command will be sent to a CAN channel in
response to a Bus Off event.
-
outputn_delaym = seconds
- This entry specifies the time
to wait after receiving a Bus Off event before sending the
Initialize command. Since a Bus Off event can only occur
while transmitting, the output of a logical channel should be specified.
There may be up to eight delay times starting with 1. The number of
seconds to wait can be specified with a resolution of 0.25.
The following two entries specify that the first and second delays
for the first logical output channel are 3.25 and 14.5 seconds respectively.
output1_delay1 = 3.25
output1_delay2 = 14.5
Each time a Bus Off event occurs, the next delay time is used.
The last defined delay time is used repeatedly for all subsequent
time delays. Using the above example entries, delays of 3.25, 14.5,
14.5 and 14.5 seconds are used for the first through fourth Bus
Off events.
Valid times are from 0.25 through 63.75 seconds. The value 0.0 is
interpreted as infinite. It makes no sense to define a delay time
following one of 0.0 because an Initialize command will never
be sent after a Bus Off event for which a delay time of 0.0
is specified.
- outputn_reset = number
- This entry specifies the number
of successful transmissions after which the delays are reset. As noted
above, each successive Bus Off event causes a wait of the the
next defined delay time before an Initialization command is
sent to the channel. If the number of successfully transmitted messages
on the CAN bus between two Bus Off events equals or exceeds
that specified by this entry, the first delay rather than the next
or last is used. Valid numbers range between 1 and 4,294,967,295.
3 Configuration File Location
All of the gateway configuration files reside on the Gryphon
in the /gryphon/gate/ directory. New configuration files may be created
directly on the Gryphon by telnetting into the Gryphon
and using pico. Another method is to create the files on a
PC and transfer them to the Gryphon via ftp. Any file name
may be used except default.
The filesystem on the Gryphon is normally write protected.
In order to add or modify a configuration file, the write protection
must be turned off. The wpflashoff command turns off the write
protection; wpflashon turns the write protection back on.
To turn the write protection off, telnet into the Gryphon and
log in as user root with a password of dggryphon. At
the prompt, enter wpflashoff. After the new or existing file
has been edited or added, enter wpflashon to restore the write
protection.
An alternate method is to use the Gryphon's front panel menu.
Select Filesystem utilities followed by Turn Flash WP
OFF entries. Use Filesystem utilities followed by Turn
Flash WP ON to restore the write protection.
4 Starting the Gateway With a Configuration File
Press and hold the left arrow button on the front of the Gryphon
until the System utilities menu entry appears. Press the down
arrow repeatedly until the Gateway Program menu entry appears.
Press the right arrow key to enter the gateway configuration selection
program. A list of gateway configuration files is then displayed.
The down and up arrow keys may be used to scroll down and up the list
if more than one configuration file is present. When the selection
arrow is in front of the desired filename, press the right arrow key
to start the gateway program using that configuration file. A new
screen will be displayed showing that gateway program is starting
with the selected configuration file. When the gateway program is
ready do begin working, the display will return to the System
utilities menu entry. Pressing the left arrow key at any time during
the above procedure, returns the display to the System utilities
menu entry.
Once the gateway has been started with the selected configuration
file, the Gryphon may be configured to start the gateway program
automatically on startup, using the same configuration file selected
with the method described above. To do so, scroll down with the down
arrow key until the System Programs menu entry appears. Press
the right arrow key to enter the System Programs configuration
program. Scroll down to the Gateway Program entry. If it is
running, the word Running will be shown in front. If it is
not running, the word Stopped will be shown in front. In either
case, press the right arrow key once to toggle the state. If the word
Running is now shown, the gateway program is running now and
will be started the next time the Gryphon is turned on. If
the word Stopped is shown, press the right arrow key once more.
Press the left arrow key to exit the System Programs configuration
program and return to the main menu.
The first paragraph describes a way to start or restart the gateway
program using a different configuration file. Doing so does not modify
the Gryphon's startup procedure vis-a-vis the gateway program.
The second paragraph describes a way to change whether or not the
gateway program is to be started at power up or not. The last selected
(used) configuration file is identified by virtue of a symbolic link
to it from default. Therefore, if the gateway program has been
set to start on power up, and the the method outlined in the first
paragraph is used to restart the gateway program with a different
configuration file, the symbolic link is changed. The newly selected
configuration file will be used on all subsequent power ups as well.
This document was translated from LATEX by
HEVEA.