How to interface with ELM327 clone

Gents,

I modified an ELM327 to build my own CAN interface and check some messages. My ELM can now read the EVCAN and the AVCAN. I was wondering if somebody can help me with some information. What are the addresses and parameters (11 bit ID bits and other parameters or AT commands) that I have to set/send in order to retrieve data? I want to read the 1DA, 1DB and 5BC messages and explore some others. I also want to monitor other information on the EV and AV buses.

I tried several masks and commands but it is more a guess and I don't get the correct information.

Appreciate if you can give me some help.

Cheers!!!

Oops, sorry if I posted this under a new topic. It is supposed to go under the "Using clone ELM327 Bluetooth OBDII adapter with Leaf" topic, I assume... Newbie to post in this forum.

Perhaps edit the subject in your first post to something like
"Using a 2-CAN-bus-modified ELM327 device".

Then, please, how did you modify the ELM327-type device
to read two CAN buses?

Specifically, which device did you use?

Is it a mini, short, stubby, or long type enclosure?

Normally, it just reads one CAN bus, right?
The 3 CAN buses available on the LEAF's OBD connector
are all 500000 baud, 11 bit MsgID buses, a common standard
for modern automotive use.

If you are having trouble with your modified device, I suggest
getting your reader code debugged with an un-modified device,
using the single CAR-CAN bus that it normally connects to.

Then, modify it to connect to the EV-CAN bus to read the
5BC (?) message that has the GID value, which normally
appears twice a second, I believe.

There is a spreadsheet with many of the "discovered" (or
suspected) MsgIDs, and logs posted on-line that can be
examined with my CAN-Do program (see the link in my
signature below).

What info are you trying to read from the AV-CAN bus?

Hi Gary,

Thanks for the reply. Yes, I am using the mini ELM327 with Bluetooth (BT). I am not reading multiple buses simultaneously, only one at a time using a switch. I opened the mini ELM, found the pins to the BT (TX and RX and other signals) and added some wires to piggy back some electronics to the mini. I am planning to use a PIC to process values via the ELM chip. I started with that as a proof of concept.

I did download the tables with the msgIDs and have been able to interpret them. I got a WattsLeft with bluetooth and in the CAN-DO mode I can read the msgIDs including the messages I am interested in, so, so far no problem.

What I want to do next is to be able to read the 5bc and other messages using the ELM chip. Unfortunately the information I have on how to request information from the CAN bus isn't too good and hard to find. I am also monitoring the 5BC message however, for some reason the information I receive is not correct. Other msgIDs are all fine.

I was wondering if I am setting the AT parameters correct, therefore I was asking what setup people use to read msgIDs on demand or how to snif the bus using the mini (CARCAN or EVCAN).

BTW: regarding the AVCAN I already could read some messages related to the console buttons.

Thanks for additional help!

Santiago

In these ELM327-clone devices, there is no ELM327 chip,
I think, but rather a PIC that has firmware to try and
emulate the operation of the real ELM327 chip.

So, google the information from the genuine ELM327 chip,
read the AT command descriptions, and go from there.

If you are having problems, it is probably with your mod, and
how it attempts to "connect" into the ELM327 clone device.

If you can read the data that you want with the un-modified
devce, then try one with a simple slide switch to chose
between the CAR CAN bus and the EV CAN bus, but just
using the ELM327 clone in the normal way.

Exactly what did you attempt to modify on the Bluetooth side
of the device?

Again, I suggest that you edit the subject of the first post
in this thread, and you might get more interest and help?

Correct, there is a PIC18F25K80 in there. I also got the information about the AT commands as well.

Since you did your meter/CAN sniffer, you may know it better. I was wondering what are the 11 bits ID and commands I have to send to retrieve the information I need (e.g. the bytes on the 5BC msg). Is it like a 7E0 or so and then a 01 00 to request it, or you just listen to the bus and capture the messages?

What I want to do (among other ideas) is to create my own gauge, but completely analog, using an old pretty panel meter that I have. Sort of retro looking gauge. I like the meters that you and others have created but rather than jumping numbers I prefer to get the analog feeling of a needle pointing a scale. My first step is using a clone "ELM327" to retrieve the msgIDs and communicate with a PIC. I will use the serial interface between the ELM clone and the BT part. It will do the analog part and other functions. In the future I plan to use a PIC with CAN (or other chips).

For now I interface via BT to a serial program to see the messages. When I monitor the messages using the AT CRA command I can see the bytes, but when I do AT CRA 5BC and others, it shows part of a message and then DATA ERROR. I was wondering how to retrieve by command a message, for example using a 7E0 and then a 01 00 request to the car unit. But that's the part I am missing information.

I will edit the subject on the first post. I haven't used much this forum in the past, so I will try. Just go to the first post and rename it?

Only a few types of data are requested and come back as
a series of 7xx messages. The ELM327 has a special mode
for setting up the requests, and sending the response(s) back
to the requester, via the Bluetooth link.

The normal MsgIDs are less than 700 hex, like the 5BC
(101 1011 1100 as eleven bits) just come along as the car
is operating, and one usually sets up a "filter" to capture
just the MsgID of interest, and they are sent back to the
requester via the Bluetooth link, as they are detected.

So, the the 7xx Request is not used to get the 5BC messages.
Of course, if you are trying to read the 5BC message from
the CAR CAN bus, you would not be successful, since that
message only occurs on the EV CAN bus.

Does that make sense to you?

Hi Gary,

Yes, it makes sense and I was doing that. I think I found the problem. When I was monitoring the 5bc message (and some others) I was getting "<DATA ERROR" messages together with the bytes. Apparently the PCI message byte is in some way invalid and creates this message. Turning of the CAN Auto Formatting (CAF) to 0 removes the messages.

What I would like to do is to inquire a particular information and get only one message response, rather than listening. Some msgIDs have a huge rate... I assume it is possible. Any clues how to do it?

If you are going to be programming the ELM327 the first place to start is with reading the manual so you know how the commands work and what the error messages mean.

Here is a link to the original ELM327 manuals which should also work with the clones too. I use the v1.4b 373KB one on this page with 76 pages.

http://www.elmelectronics.com/obdic.html#ELM327

Yes, I did it but got stuck with the <DATA ERROR message. I was trying to send some commands and understand the 11 bit examples but isn't too clear. Thanks Jim.

Is you write exactly what you are sending, and exactly what you receive,
for an entire short session, we might be able to help you better.

This is pretty old now but I'd like to contribute to the pool of knowledge here anyway. The DATA ERROR message is coming up because you are trying to have the ELM327 auto-format the data. You need to issue a ATCAF 0 to turn off auto-formatting.

Let me know if you are still working on this!