Hi my name is Gian and I saw your post on PriusChat about using ELM327 as CAN message monitor.
I am trying to simply use my ELM327 to read the CAN traffic on my car and when I use the command 'AT MA' the result is not what I want.
In fact after 2 or 3 CAN messages the communication does not work and the ELM327 seems stuck.
I have read you found the solution to read the CAN traffic continuosly without problems and I was wondering how you did it.
I also studied your project (very very well done) and I found the setting that you use...but it seems commented and I do no know if it is the actual one you have been using.
"void OBD_Class::init(){// initialize OBDUSB device
//sendcmd("\r"); wait(1.0); readandlogdata();// send \r to wake it up
sendsettingscmd("\r");
//sendcmd("ATZ\r"); wait(1.0); readandlogdata();// ATZ reset need extra time lowest 0.8 sec tested OK
sendsettingscmd("ATZ\r");
//sendsettingscmd("AT PP 01 SV 00\r");// set headers ON by default, only need to do once
//sendsettingscmd("AT PP 01 ON\r");
// sendsettingscmd("STSN\r"); //show device serial number
// sendsettingscmd("STSLCS\r"); //show PowerSave configuration
// sendsettingscmd("STI\r"); //show firmware version
// sendsettingscmd("STDIX\r"); //show device version
// sendsettingscmd("ATPPS\r"); //show programmable parameters list
// sendsettingscmd("ATSP6\r"); // set protocol to #6
// sendsettingscmd("ATDPN\r"); // check protocol should be 6
// sendsettingscmd("ATH1\r"); // turn on header
// sendsettingscmd("ATCAF0\r"); // turn off formatting
// sendsettingscmd("ATST FF\r"); // set timeout in units of 4 ms; Flyer suggested using FF, try shorter timeout in case Fujitsu goes to sleep erroneously
//sendsettingscmd("ATCM 00000000\r"); // set CAN ID mask // moved to UI.cpp
//sendsettingscmd("AT CSM 0\r");//AT CSM 0 requested by ccdisce"
Thank you so much
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Hi you can download STN Term here https://www.scantool.net/scantool/downloads/utilities/
or use a similar terminal program to diagnose the communication. What's the baud rate? It needs to be high enough. If you use a cheap "clone" it may not work.
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Which OBD2 device do you have? And, always about sniffing the CAN bus, every time you start your system (app and device), do you set the OBD2 device with AT commands? I am asking this because I have noticed that, if when I set the device there are CAN msgs on the bus, the elm327 does not like it at does not want to work after....do you have any idea?
thank you so much
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Yesterday I contact OBDLink to understand their bluetooth products potential. They said to me that their MX Bluetooth (~99$) can reach 2M of baudrate and they can completely support the ATMA command. So, I think I am going to buy it but I am afraid to have the same problem...
I have already realized a USB solution and it works withouth problem, now I want to try a bluetooth one.
Last question, is there a way so send completely custom CAN messages using the OBD2 devices? If yes, which are the AT commands that allow that?
Thanks
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You can send any CAN message so I don't know what you meant by custom CAN messages. Here is the commands in the command.txt file that goes with my program:
STI,STDIX,0;//show firmware version, device version
STSN,STSLCS,0;//show device serial number, PowerSave configuration
ATPPS,AT@1,0; //show programmable parameters list, device description
ATSP6,ATDPN,0; // set protocol to #6, check protocol should be 6
ATL1,ATH1,0; // turn on line feed, turn on header
ATCAF0,ATSTFF,0; // turn off formatting, set timeout in units of 4 ms; Flyer suggested using FF, may try shorter timeout in case Fujitsu goes to sleep erroneously
ATSH7E2,0521C3C442D3,1;//query inverter & MG Nm & T, 12V, brake light
ATSH7E0,03010E04,2;//query IGN & load
ATSH7E0,0221CD,3;//query ICE torque (N-m) iceNm2
ATSH7E0,05213C3E2E32,3;//query catT1&2 EVAP
ATSH7E3,0421d0cecf,2;//query HV battery
ATSH7E0,020105,3;//query ICE coolant T
ATSH7E0,032133F5,3;//query atm, misfire
ATSH7E3,022131,3;//DTC clear run dist
ATSH7E0,020110,3;//MAF air flow rate (grams/sec) ((A*256)+B)/100
I made the CAN messages bold face.
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I have spent several hours to figure the OBDLink out using my arduino+bluetooth. The only thing I am able to do correctly is to send custom msgs. Other than that, reading messages from the CAN bus does not work properly at all. I have tried to change baud rate, setting, filters etc....but nothing. After few messages I have always buffer full....
do you have any idea?
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Buffer full usually means the communication is not fast enough. Are you sure you can set 2M baud rate? Maybe post a message on OBDLink's support forum. They are quite responsive. Good luck!
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Finally I have figured it out! The bluetooth version is not able to manage all the CAN traffic on the bus (also increasing the baud rate the problem remains). Instead, applying filters I am able to read up to 10 different CAN IDs without problems (I did not try more than 10, I believe it is possible to go up a little)...
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Hello Gian, Could please let me know whow you achieved the filter of multiple CAN IDs? I want to filter (receive) CAN IDs 0x12A ans 0x174 (for example)- could you please give an example how to achieve that in ELM327?
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Hi my name is Gian and I saw your post on PriusChat about using ELM327 as CAN message monitor.
I am trying to simply use my ELM327 to read the CAN traffic on my car and when I use the command 'AT MA' the result is not what I want.
In fact after 2 or 3 CAN messages the communication does not work and the ELM327 seems stuck.
I have read you found the solution to read the CAN traffic continuosly without problems and I was wondering how you did it.
I also studied your project (very very well done) and I found the setting that you use...but it seems commented and I do no know if it is the actual one you have been using.
"void OBD_Class::init(){// initialize OBDUSB device
//sendcmd("\r"); wait(1.0); readandlogdata();// send \r to wake it up
sendsettingscmd("\r");
//sendcmd("ATZ\r"); wait(1.0); readandlogdata();// ATZ reset need extra time lowest 0.8 sec tested OK
sendsettingscmd("ATZ\r");
//sendsettingscmd("AT PP 01 SV 00\r");// set headers ON by default, only need to do once
//sendsettingscmd("AT PP 01 ON\r");
// sendsettingscmd("STSN\r"); //show device serial number
// sendsettingscmd("STSLCS\r"); //show PowerSave configuration
// sendsettingscmd("STI\r"); //show firmware version
// sendsettingscmd("STDIX\r"); //show device version
// sendsettingscmd("ATPPS\r"); //show programmable parameters list
// sendsettingscmd("ATSP6\r"); // set protocol to #6
// sendsettingscmd("ATDPN\r"); // check protocol should be 6
// sendsettingscmd("ATH1\r"); // turn on header
// sendsettingscmd("ATCAF0\r"); // turn off formatting
// sendsettingscmd("ATST FF\r"); // set timeout in units of 4 ms; Flyer suggested using FF, try shorter timeout in case Fujitsu goes to sleep erroneously
//sendsettingscmd("ATCM 00000000\r"); // set CAN ID mask // moved to UI.cpp
//sendsettingscmd("AT CSM 0\r");//AT CSM 0 requested by ccdisce"
Thank you so much
Hi you can download STN Term here
https://www.scantool.net/scantool/downloads/utilities/
or use a similar terminal program to diagnose the communication. What's the baud rate? It needs to be high enough. If you use a cheap "clone" it may not work.
The ELM327 is the original one but the baudrate that I am ableto reach is 57.6....
you think the only problem is that?
Last edit: Gian 2015-10-01
Right 57.6K is probably too slow. I use 2M on my car. I think you need at least 500K, for Prius anyway.
Which OBD2 device do you have? And, always about sniffing the CAN bus, every time you start your system (app and device), do you set the OBD2 device with AT commands? I am asking this because I have noticed that, if when I set the device there are CAN msgs on the bus, the elm327 does not like it at does not want to work after....do you have any idea?
thank you so much
I use OBDLink and OBDLink SX. Both are USB wired. Yes I always initialize the device with AT commands and no problems.
OK thank you so much, have you tried a bluetooh one?
No bluetooth is too slow for ATMA, at least for my Prius.
Yesterday I contact OBDLink to understand their bluetooth products potential. They said to me that their MX Bluetooth (~99$) can reach 2M of baudrate and they can completely support the ATMA command. So, I think I am going to buy it but I am afraid to have the same problem...
I have already realized a USB solution and it works withouth problem, now I want to try a bluetooth one.
Last question, is there a way so send completely custom CAN messages using the OBD2 devices? If yes, which are the AT commands that allow that?
Thanks
Wow I didn't know the MX can reach 2M baud rate.
You can send any CAN message so I don't know what you meant by custom CAN messages. Here is the commands in the command.txt file that goes with my program:
STI,STDIX,0;//show firmware version, device version
STSN,STSLCS,0;//show device serial number, PowerSave configuration
ATPPS,AT@1,0; //show programmable parameters list, device description
ATSP6,ATDPN,0; // set protocol to #6, check protocol should be 6
ATL1,ATH1,0; // turn on line feed, turn on header
ATCAF0,ATSTFF,0; // turn off formatting, set timeout in units of 4 ms; Flyer suggested using FF, may try shorter timeout in case Fujitsu goes to sleep erroneously
ATSH7E2,0521C3C442D3,1;//query inverter & MG Nm & T, 12V, brake light
ATSH7E0,03010E04,2;//query IGN & load
ATSH7E0,0221CD,3;//query ICE torque (N-m) iceNm2
ATSH7E0,05213C3E2E32,3;//query catT1&2 EVAP
ATSH7E3,0421d0cecf,2;//query HV battery
ATSH7E0,020105,3;//query ICE coolant T
ATSH7E0,032133F5,3;//query atm, misfire
ATSH7E3,022131,3;//DTC clear run dist
ATSH7E0,020110,3;//MAF air flow rate (grams/sec) ((A*256)+B)/100
I made the CAN messages bold face.
yes it is perfect as example!!! I just order the bluetooth one, so in these days I will try it! I will keep you posted
I have spent several hours to figure the OBDLink out using my arduino+bluetooth. The only thing I am able to do correctly is to send custom msgs. Other than that, reading messages from the CAN bus does not work properly at all. I have tried to change baud rate, setting, filters etc....but nothing. After few messages I have always buffer full....
do you have any idea?
Buffer full usually means the communication is not fast enough. Are you sure you can set 2M baud rate? Maybe post a message on OBDLink's support forum. They are quite responsive. Good luck!
Finally I have figured it out! The bluetooth version is not able to manage all the CAN traffic on the bus (also increasing the baud rate the problem remains). Instead, applying filters I am able to read up to 10 different CAN IDs without problems (I did not try more than 10, I believe it is possible to go up a little)...
Hello Gian, Could please let me know whow you achieved the filter of multiple CAN IDs? I want to filter (receive) CAN IDs 0x12A ans 0x174 (for example)- could you please give an example how to achieve that in ELM327?
Congrats!