Use OBDLlink MX+ as CAN-BUS reader does not show any data

away_yang

first of all, thanks for all the great guys in this forum whom shared the software, ideas for how to tap into the private-CAN network and collect data.

I have refer to @Cali_Chuck 's topic https://racechrono.com/forum/discussion/comment/14182, do the exact same 4-wires(Power/Ground/CanH/CanL), wired to BCP panel at passenger side of my BMW X1.

I also used a CAN sniffer Kvaser Leaf to verified, all CAN broadcast message are well received.

However, when i connect the the OBDLink MX+ to the port, and use (protocol 6, 11 bit at 500KBuad), default initialisation commands in Racechrono, setup some CAN ID/items which I have extracted from the sniffer, nothing comes up, even no raw data refreshing, no matter when testing or logging.

Also, I've tried send AT/ST commands directly to OBDLink, it can receive all CAN messages.

Just wondering, is there any special initialisation commands for OBDLink MX+ at CAN-BUS logger mode?

Open Settings, Monitor all messages:

13 ATZ 38:57.513 14 ELM327 v1.4b 38:58.477 15 > 38:58.477 16 ATE0 39:06.526 17 ATE0 39:06.586 18 OK 39:06.586 19 > 39:06.586 20 ATH1 39:13.541 21 OK 39:13.616 22 > 39:13.616 23 ATAT1 39:21.067 24 OK 39:21.157 25 > 39:21.157 26 STP33 39:28.144 27 OK 39:28.232 28 > 39:28.232 29 STCAF0 39:58.952 30 OK 39:59.045 31 > 39:59.045 32 ATMA 40:11.501 33 s 40:14.224 34 36E 1B FC FE FF 14 40:14.250 35 0CA 07 23 00 00 00 00 FD F7 40:14.250 36 387 1C F3 FF 0A FF FF FF FF 40:14.250 37 1A1 1E CC 00 00 F1 40:14.250 38 0F3 04 0E 05 00 F0 40:14.250 39 0F3 05 00 05 00 F0 C4 40:14.250 40 0D9 1D F4 00 10 FF FF 7F FF 40:14.250 41 200 15 08 71 FF FF FF FF FF 40:14.250 42 0D9 1C FA 00 10 FF FF 7F FF 40:14.250 43 1A1 1F C5 00 00 F1 40:14.250 44 412 14 7E 87 98 68 AC D9 84 40:14.250 45 30C 1B F9 00 00 14 40:14.250 46 2BB 1B FE 97 3B F2 40:14.250

Applied CAN Filtering and flow control with pattern and mask.

4191 ATCF0A5 47:09.138 4192 OK 47:09.205 4193 > 47:09.205 4194 ATCMFF0 47:29.626 4195 OK 47:29.730 4196 > 47:29.730 4197 STFFCA0A5,FF0 48:24.746 4198 OK 48:24.812 4199 > 48:24.812 4200 STM 48:28.706 4201 q 48:31.989 4202 0A5 00 00 FC F7 FF 7B 0C C1 48:32.043 4203 0AB 0A 0C 04 00 00 00 DD DD 48:32.043 4204 0A5 0E 07 FC F7 FF 70 0C C1 48:32.043 4205 0A5 0F 09 FC F7 FF 70 0C C1 48:32.043 4206 0A5 11 00 FC F7 FF 65 0C C1 48:32.043 4207 0A5 16 0E FC F7 FF 61 0C C1 48:32.043 4208 0A5 1D 09 FC F7 FF 6C 0C C1 48:32.043 4209 0A5 11 00 FC F7 FF 65 0C C1 48:32.043 4210 0A5 16 0E FC F7 FF 61 0C C1 48:32.043 4211 0A5 0A 00 FC F7 FF 77 0C C1 48:32.043 4212 0AB 0B 02 04 00 00 00 DD DD 48:32.043 4213 0A5 0B 0E FC F7 FF 77 0C C1 48:32.043 4214 0A5 0B 09 FC F7 FF 83 0C C1 48:32.043 4215 0A5 0D 00 FC F7 FF 86 0C C1 48:32.043 4216 0A5 0C 0E FC F7 FF 86 0C C1 48:32.043 4217 0A5 0D 00 FC F7 FF 86 0C C1 48:32.043 4218 0A5 08 07 FC F7 FF 74 0C C1 48:32.043 4219 0A5 08 07 FC F7 FF 74 0C C1 48:32.043 4220 0A5 00 00 FC F7 FF 7B 0C C1 48:32.043 4221 0A5 07 0E FC F7 FF 7F 0C C1 48:32.043 4222 0A5 0A 07 FC F7 FF 83 0C C1 48:32.043 4223 0A5 0C 0E FC F7 FF 86 0C C1 48:32.043

away_yang

I have extract the raw output as below, CAN messages were flow in.

I have the CAN item PID set as 165 (0x0A5), message has been found below, but just no update on the CAN test items or session live data.

<--08:08:35.785 IN -->0A5 17 01 FF F7 FF 70 0C C1 \r

<--08:08:30.685 IN -->STOPPED\r\r> <--08:08:32.691 OUT-->ATE0\r <--08:08:32.782 IN -->ATE0\rOK\r\r> <--08:08:32.783 OUT-->ATL0\r <--08:08:32.795 IN -->OK\r\r> <--08:08:33.800 OUT-->ATSP0\r <--08:08:33.868 IN -->OK\r\r> <--08:08:33.868 OUT-->ATS0\r <--08:08:33.875 IN -->OK\r\r> <--08:08:33.976 OUT-->ATZ\r <--08:08:34.899 IN -->\r\rELM327 v1.4b\r\r> <--08:08:35.000 OUT-->ATH1\r <--08:08:35.068 IN -->ATH1\rOK\r\r> <--08:08:35.169 OUT-->STCAF 0\r <--08:08:35.264 IN -->STCA <--08:08:35.291 IN -->F 0\rOK\r\r> <--08:08:35.392 OUT-->ATMA\r <--08:08:35.476 IN -->ATMA\r <--08:08:35.481 IN -->297 15 F6 90 80 80 00 A8 \r <--08:08:35.483 IN -->0D9 1D F4 00 10 FF FF 7F FF \r <--08:08:35.514 IN -->1E0 04 00 80 FD F4 \r <--08:08:35.517 IN -->1A1 1F C5 00 00 F1 \r <--08:08:35.543 IN -->0D9 1C FA 00 10 FF FF 7F FF \r <--08:08:35.561 IN -->294 1 <--08:08:35.563 IN -->B C8 FE FF 14 \r <--08:08:35.649 IN -->1A1 1E CC 00 00 F1 \r <--08:08:35.650 IN -->2D2 14 FF FF 43 F4 \r <--08:08:35.708 IN -->0CA 06 2D 00 00 00 00 FD \r <--08:08:35.720 IN -->17D 17 58 00 00 00 00 20 C0 \r <--08:08:35.781 IN -->0D9 1D F4 00 10 FF FF 7F FF \r <--08:08:35.785 IN -->0A5 17 01 FF F7 FF 70 0C C1 \r <--08:08:35.828 IN -->5ED 1B 00 00 00 FF 06 00 0F \r <--08:08:35.830 IN -->1A1 1F C5 00 00 F1 \r <--08:08:35.831 IN -->0D9 1C FA 00 10 FF FF 7F FF \r <--08:08:35.844 IN -->2A7 13 F8 FE FF 14 \r

away_yang

Keep digging in the raw messages,

STFPA 0A5,7FF was rejected, it was followed the instruction from ST's reference, maybe the scantool's issue.
STFAP 0A5,7FF , is accepted , but STM does not receive any data.

IOS version is not able access to raw output file, i have to use andriod version, still keep digging......

<--14:14:33.807 OUT-->ATZ\r <--14:14:34.733 IN -->\r\rELM327 v1.4b\r\r> <--14:14:36.738 OUT-->ATE0\r <--14:14:36.806 IN -->ATE0\rOK\r\r> <--14:14:36.806 OUT-->ATL0\r <--14:14:36.815 IN -->OK\r\r> <--14:14:37.818 OUT-->ATSP0\r <--14:14:37.887 IN -->OK\r\r> <--14:14:37.887 OUT-->ATS0\r <--14:14:37.905 IN -->OK\r\r> <--14:14:38.005 OUT-->STFPC\r <--14:14:38.073 IN -->OK\r\r> <--14:14:38.174 OUT-->STFPA 0A5,7FF\r <--14:14:38.211 IN -->?\r\r> <--14:14:38.312 OUT-->STFPA 0A5,7FF\r <--14:14:38.359 IN -->?\r\r> <--14:14:38.459 OUT-->STFPA 0A5,7FF\r <--14:14:38.523 IN -->?\r\r> <--14:14:38.523 OUT-->ATH1\r <--14:14:38.531 IN -->OK\r\r> <--14:14:38.532 OUT-->STM\r <--14:14:38.544 IN -->SEARCHING...\r <--14:14:38.788 IN -->2D211FFFFC8F3\r <--14:14:38.792 IN -->1A11FC50000F1\r <--14:14:38.808 IN -->2001B0A31FFFFFFFFF <--14:14:38.810 IN -->F\r <--14:14:38.902 IN -->17D16560000000020C0\r <--14:14:38.902 OUT-->\r <--14:14:38.909 IN -->STOPPED\r\r> <--14:14:38.909 OUT-->STFCP\r\r <--14:14:38.917 IN -->OK\r\r> <--14:14:38.917 OUT-->STFAP 0A5,7FF\r <--14:14:38.925 IN -->OK\r\r> <--14:14:38.925 OUT-->STM\r <--14:14:43.940 OUT-->\r <--14:14:43.982 IN -->STOPPED\r\r> <--14:14:43.983 OUT-->STM\r <--14:14:48.999 OUT-->\r <--14:14:49.035 IN -->STOPPED\r\r> <--14:14:49.035 OUT-->STM\r <--14:14:54.051 OUT-->\r <--14:14:54.108 IN -->STOPPED\r\r> <--14:14:54.109 OUT-->STM\r <--14:14:59.123 OUT-->\r <--14:14:59.172 IN -->STOPPED\r\r> <--14:14:59.173 OUT-->STM\r <--14:15:00.355 OUT-->\r

Cali_Chuck

@away_yang - this seems similar to the situation I described in my long post where I was seeing data just fine with the CSS CL1000 sniffer but not with the OBDLink MX+. But what is not the same is that you are apparently tied into the actual car CAN, whereas my problem was on a "private" CAN with just two nodes that did not include the car.

I understand when you say that you are seeing valid CAN data from your sniffer that means you have verified that the wiring harness you have built is working properly so it's not a pin problem (hopefully). The question I guess I would ask there is - have you really sanity checked the sniffer data to ensure that in fact what you are seeing are real CAN messages? And that they behave in the expected way?

For example - if you go for a test drive and vary the speed or braking or something else in a predictable way while the sniffer is running, do you see the speed or brake or other channel change in your analyzer tool in a matching way? I was able to do this easily with the CSS sniffer because their analysis tool includes a graphical mode where you can plot an arbitrary CAN channel over time - thus CSS lets one produce a speed chart or a brake chart from inside the tool.

If you are sure you are getting real CAN data to the sniffer (thereby proving your cable works) then the next thing to check is the CAN bus ack. Maybe BMW CAN bus works differently than Porsche and OBDLink requires an ack. Doesn't really make sense to me (and I'm a low level networking guy) but that's all I can think of.

So in my case as documented in my post the OBDLink people gave me try adding "STCMM 1\n" in the RaceChrono initialization string which will force it to issue a gratuitous ack for every CAN packet. In theory all the other BMW devices on the bus should already be doing this so the OBDLink shouldn't have to but clearly it's not working as you expect.

One more question - did you set up the OBDLink correctly in RaceChrono as a CAN reader and NOT as an OBD reader? It won't work if provisioned for OBD mode.

away_yang

For the last question, I m 100% sure it's configured as CAN-BUS reader in Racechrono.

For data sanity check, i used the 0x0A5 as a reference for RPM, it matched my pedal action, so i m pretty sure the data is in a right way (at least for 0x0A5)

and you are right about the STCMM, the nodes on BMW's CAN network already doing ACK works, i dont need to do ack at the OBDLink.

refer to my first try, use terminal to operate the OBDLink directly, with different approach (AT commands) of filtering setup, the STM command can correctly receive the 0x0A5 messages. With Racechrono's raw files, it use ST commands, and applying filter on different stage of CAN filters.

Tried combined two parts of filtering commands, I can get STM flow with 0x0A5 messages in terminal.

My current guess is at the filtering part, plan to spend some learning at scantools' reference document, hopefully I can get the data flows in Racechrono at this weekend......

Cali_Chuck

I figured you had CAN data as 0x0A5 looks like a CAN ID to me. But had to ask.

That said, you've gone farther than I needed to go. The "filter" I am using is simply RaceChrono formulas for each PID and then I sometimes used "Live Data" mode to monitor them in realtime. Other than the STCMM command I have not needed to do any extra initialization on my Porsche setup.

I also checked into whether the OBDLink has a diagnostic mode that will dump live data but they told me it does not. That would be very helpful in this type of situation. I think you're doing the next best thing.

On IOS I have never been able to get RaceChrono to actually dump a raw file, despite several tries.

away_yang

Regarding the OBDLink MX+ diagnostic, as you said, they(scantool) didn't provide any diagnostic mode/tools. An the bluetooth mode it used does not provide an actual COM port for terminal consoles from PC.

For diagnostic: I have found "OBD Now terminal" in android platform, which can access OBDLink at console mode, that said, i can send AT/ST commands directly to OBDLink like a command prompt, which is very helpful for real time diagnostic. Also, android version of RC can reach to session folder for raw file, IOS does not allow this kind of access, hence you cannot the the raw output file from IOS version, I guess.

Base on the reading:

1.CAN bus message diagram

1st stage is CAN HW Filter (ATCF/ATCM), only allow matched. 2nd stage is Flow Control Filter(STFFCA), separate ISO11898 Frame format and ISO15765 Frame format.

3rd stage If the frame is ISO11898, then it will flow to Pass Filter(STFPA) which Racechrono default initialized with the PID. If the frame is ISO15765, it will flow with another routing which does not involve with Passfilter.

Last stage, Block Filters (STFBA) will drop those matched messages, and transmit those not matched to UART like (STM) command.

ATM/STM commands is BYPASSED ALL filters, hence i can get all the messages.

OBD Bus message(Non-CAN protocol) diagram:

1st Stage is Pass Filter(STFPA) Last Stage is Block Filter(STFBA)

Base on this diagram and the attempts above, i have several possible guess:

RC used "Non-CAN protocol" diagram/commands to initial the CAN-BUS logger mode. Because the Passfilter already setup correctly but not data flow in, then it means there must be additional filters before Pass Filter, hence it's definitely not a "Non-CAN protocol" message.
If it's a CAN message, the CAN HW Filter need to setup/initial to let messages come in, which RC didnt implemented as "Non-CAN protocol" does not required this to setup.
Hopefully the CAN messages is ISO11898 format, pass to the Pass Filter, which RC already did, i dont need to do extra works. If it's ISO15765, then i need spend more time in CAN specified Filtering/Flow controls.

Anyway, it will take time in the car instead of sit in front of my computer. lol.

away_yang

@Cali_Chuck Cheers, I have got the data flow as expected. Thanks for the help, and your 718 post is a valuable reference.

Here's the findings:

Reference：OBDLink® Family Reference and Programming Manual https://www.scantool.net/scantool/downloads/682/obdlink_frpm_f.pdf Page 56, Message Filtering

RC use PassFilter(STFPA) for CAN ID filtering, but this will only work at ISO11898 frames, ISO15765/J1939 Frames will not go through this filter.
RC initial protocol us ATSP command, and by default, only provide 0₆ protocols at the APP interface, but no ISO11898 option available in that list.
CAN Hardware Filter in OBDLink will auto update, once the protocol is set via ATSP or STP command, no need manual setup.

In short, it need to set OBDLink to parse the frames in ISO11898, but there is no GUI options to do this.

I m now using ST commands in the custom initialisations, everything works now.

STP31\nSTPO\n

@aol_of_RaceChrono Is this a normal issue or just brand/car specified issue?

<--14:05:59.432 OUT-->ATZ\r <--14:06:00.339 IN -->\r\rELM327 v1.4b\r\r> <--14:06:02.346 OUT-->ATE0\r <--14:06:02.450 IN -->ATE0\rOK\r\r> <--14:06:02.451 OUT-->ATL0\r <--14:06:02.468 IN -->OK\r\r> <--14:06:03.472 OUT-->ATSPA6\r <--14:06:03.523 IN -->OK\r\r> <--14:06:03.524 OUT-->ATS0\r <--14:06:03.535 IN -->OK\r\r> <--14:06:03.636 OUT-->STP31\r ----> Set protocol to 31 - ISO 11898, 11-bit Tx, 500kbps, var DLC <--14:06:03.721 IN -->OK\r\r> <--14:06:03.822 OUT-->STPO\r ----> Open protocol <--14:06:03.892 IN -->OK\r\r> <--14:06:03.893 OUT-->ATH1\r <--14:06:03.913 IN -->OK\r\r> <--14:06:03.913 OUT-->STM\r <--14:06:08.928 OUT-->\r <--14:06:09.002 IN -->STOPPED\r\r> <--14:06:09.002 OUT-->STFCP\r\r <--14:06:09.011 IN -->OK\r\r> <--14:06:09.011 OUT-->STFAP 1A1,7FF\r <--14:06:09.020 IN -->OK\r\r> <--14:06:09.021 OUT-->STFAP 0A5,7FF\r <--14:06:09.032 IN -->OK\r\r>