ELM624
AT Commands
The ELM624 can accept internal configuration
wish to customize their settings, such as turning the
character echo off, or perhaps quiet mode on, by
issuing these commands. Doing this is as easy as
sending AT E0, or AT Q1, followed by the return
character. Note that this version of the ELM624 is only
able to accept one command per line, so changing
multiple settings requires one line for each change.
The following summarizes the ‘AT’ commands that
are recognized by this version of the ELM624. Note
that the character ‘0’ is the number ‘zero’:
commands at any time, in much the same manner that
modems do. Any command sent to the ELM624 which
begins with the letter ‘A’ followed by the letter ‘T’ is
assumed to be an internal configuration (or ‘AT’)
command. These commands are executed upon
receipt of the terminating carriage return character,
and are acknowledged with some form of response,
which may be as simple as the characters ‘OK’.
The ELM624’s factory default settings should be
appropriate for most applications, but some users may
2D
[ use version 2 Defaults ]
R options to their default (or factory) settings, as
when power is first applied. It provides a fast and
efficient way to restore the settings without having to
wait through the time delay of a power up reset.
This command is used to set several of the options
to their default (or factory) settings, as if this were a
v2.x IC. In the 2D mode, linefeed characters are not
sent automatically after each carrige return, and
there is no prompt character generated when the IC
is ready to accept the next command. Other than
that, the E, C, D, Q and R options are set the same
as those discussed here for the v3.0 IC.
D0 and D1
[ Duplicate off (0) or on (1) ]
While the LANC message structure allows for four
command bytes to be sent, most devices only use
the first two, and ignore the others. For convenience,
the ELM624 can be provided with either two or four
bytes to send, but if it is provided with only two, it
needs to know what to insert into the other two
positions of the four byte command field.
C0 and C1
[ send all (0) or only Changes (1) ]
These commands specify when the Control L status
bytes are to be returned on the RS232 bus. With the
C1 command, values are only sent when there is a
change from the previous eight bytes, while with C0
the response bytes are always sent. For most
devices, setting C1 will have little noticeable effect,
as the LANC responses usually alternate between
status and time-code values, so they do continually
change. The default is C1, send on change.
If the duplicate option is turned on, the two command
words that were provided to the ELM624 will be
inserted into the word 0 and word 1 positions, and
then will be duplicated and used for the other two
positions (words 2 and 3). If the duplicate option is
off, no duplication will occur, and 0’s will be sent in
positions 2 and 3 instead. Setting the duplicate
option to off may be useful if you suspect that a
unique device is providing status bytes in positions 2
and 3 and you do not want to overwrite them. The
default setting is D1, duplicate on.
CS
[ Check Sync ]
This command is used to determine (check) if the
connected LANC device is sending synchronizing
signals or not. If the signals are correct, a ‘SYNC
OK’ message will be returned. If there is a problem,
either ‘NO SYNC’ or ‘SYNC ERROR’ will be
returned. This provides a quick way to see if a
device is powered and ready to accept commands.
E0 and E1
[ Echo off (0) or on (1) ]
These commands control whether all characters
received on the RS232 port are retransmitted (or
echoed) back to the host computer. To reduce traffic
on the RS232 bus, and perhaps simplify some
computer software, users may wish to turn echoing
off by issuing E0. The default is E1, echo on.
D
[ set all to Defaults ]
This command is used to reset the E, C, D, L, Q, and
ELM624DSD
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