# Question about the description file. **URL:** \ **Category:** Help, tips and tricks\ **Created:** [September 10, 2021, 9:53pm UTC](https://forum.realdash.net/t/question-about-the-description-file/1035 "2021-09-10T21:53:47Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![Mozgolom](https://forum.realdash.net/letter_avatar_proxy/v4/letter/m/b487fb/32.png) [@Mozgolom](https://forum.realdash.net/u/Mozgolom)\ **Post date:** [September 10, 2021, 9:53pm UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/1 "2021-09-10T21:53:47Z")
Some data is present in the can bus in the same frame, for example with can id 06E1. The first 3 bytes indicate which data (which parameter) and the next 2 bytes are the parameter value. So all the data is transmitted with the same CAN id in bytes 4 and 5. The difference is only in bytes 1, 2 and 3. This is the name of the parameter. How to describe such variables in the description file? ---
**Author:** ![realdashdev](https://forum.realdash.net/user_avatar/forum.realdash.net/realdashdev/32/6_2.png) [@realdashdev](https://forum.realdash.net/u/realdashdev)\ **Post date:** [September 13, 2021, 5:07am UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/2 "2021-09-13T05:07:18Z")
I think you are referring to ‘Composite ID’ support. It is supported and described here: [https://github.com/janimm/RealDash-extras/blob/master/RealDash-CAN/realdash-can-description-file.md](https://github.com/janimm/RealDash-extras/blob/master/RealDash-CAN/realdash-can-description-file.md) ---
**Author:** ![Mozgolom](https://forum.realdash.net/letter_avatar_proxy/v4/letter/m/b487fb/32.png) [@Mozgolom](https://forum.realdash.net/u/Mozgolom)\ **Post date:** [September 14, 2021, 8:10pm UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/3 "2021-09-14T20:10:34Z")
For example, the frames look like this: 7e9 05 62 2C 7A ХХ ХХ 00 00. 62 2C 7A - this is the data ID (byte 1, byte 2, byte 3), and XX XX - this is the data (byte 4, byte 5). This is the variable 1. 7e9 05 62 2D 08 ХХ ХХ 00 00. 62 2D 08 - this is the data ID, (byte 1, byte 2, byte 3) and XX XX - this is the data (byte 4, byte 5). This is the variable 2. And so on. So, always the data I need is in a frame with the same id 7E9. The offset is also the same and is equal to 3. The data length is also the same and is equal to 2 bytes. The data is always in bytes 4 and 5, but depending on the contents of bytes 1, 2 and 3 refer to different parameters. How can I describe such data? ---
**Author:** ![realdashdev](https://forum.realdash.net/user_avatar/forum.realdash.net/realdashdev/32/6_2.png) [@realdashdev](https://forum.realdash.net/u/realdashdev)\ **Post date:** [September 15, 2021, 9:06am UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/4 "2021-09-15T09:06:36Z")
> 7e9 05 62 2C 7A ХХ ХХ 00 00. 62 2C 7A - this is the data ID (byte 1, byte 2, byte 3), and XX XX - this is the data (byte 4, byte 5). This is the variable 1. > 7e9 05 62 2D 08 ХХ ХХ 00 00. 62 2D 08 - this is the data ID, (byte 1, byte 2, byte 3) and XX XX - this is the data (byte 4, byte 5). This is the variable 2. And so on. Declare each composite ID frame separately in XML file: ```plaintext ``` ---
**Author:** ![Mozgolom](https://forum.realdash.net/letter_avatar_proxy/v4/letter/m/b487fb/32.png) [@Mozgolom](https://forum.realdash.net/u/Mozgolom)\ **Post date:** [September 17, 2021, 6:41pm UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/5 "2021-09-17T18:41:34Z")
I tried it like this And like this Nothing is working. ---
**Author:** ![realdashdev](https://forum.realdash.net/user_avatar/forum.realdash.net/realdashdev/32/6_2.png) [@realdashdev](https://forum.realdash.net/u/realdashdev)\ **Post date:** [September 20, 2021, 2:48pm UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/6 "2021-09-20T14:48:50Z")
You cant have two values with same name ‘variable1’. ---
**Author:** ![Mozgolom](https://forum.realdash.net/letter_avatar_proxy/v4/letter/m/b487fb/32.png) [@Mozgolom](https://forum.realdash.net/u/Mozgolom)\ **Post date:** [September 20, 2021, 4:54pm UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/7 "2021-09-20T16:54:23Z")
The real names of the variables are different. ---
**Author:** ![realdashdev](https://forum.realdash.net/user_avatar/forum.realdash.net/realdashdev/32/6_2.png) [@realdashdev](https://forum.realdash.net/u/realdashdev)\ **Post date:** [September 21, 2021, 6:07am UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/8 "2021-09-21T06:07:10Z")
If you just add a text gauge and link it to your variable, do you see any value there? This is a bit difficult to troubleshoot without having the same hardware, sorry ☹ ---
**Author:** ![Mozgolom](https://forum.realdash.net/letter_avatar_proxy/v4/letter/m/b487fb/32.png) [@Mozgolom](https://forum.realdash.net/u/Mozgolom)\ **Post date:** [September 21, 2021, 4:57pm UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/9 "2021-09-21T16:57:46Z")
I have created both text sensors and indicators at the same time, but they do not show anything. ---
**Author:** ![Mozgolom](https://forum.realdash.net/letter_avatar_proxy/v4/letter/m/b487fb/32.png) [@Mozgolom](https://forum.realdash.net/u/Mozgolom)\ **Post date:** [September 21, 2021, 6:23pm UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/10 "2021-09-21T18:23:33Z")
So, which syntax is correct? Or ---
**Author:** ![realdashdev](https://forum.realdash.net/user_avatar/forum.realdash.net/realdashdev/32/6_2.png) [@realdashdev](https://forum.realdash.net/u/realdashdev)\ **Post date:** [September 22, 2021, 6:10am UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/11 "2021-09-22T06:10:06Z")
Oh, man I’m sorry. I gave you wrong examples on previous post 😢 (fixed them now). The correct format is CAN\_ID:COMPOSITE\_ID,COMPOSITE\_ID\_OFFSET,COMPOSITE\_ID\_LENGTH - CAN\_ID: the frame CAN ID. - COMPOSITE\_ID: Composite ID that is read from frame data. - COMPOSITE\_ID\_OFFSET: Offset (in bytes) where Composite ID is in frame data. - COMPOSITE\_ID\_LENGTH: Length (in bytes) of the Composite ID in frame data. Example: ```plaintext ``` ---
**Author:** ![Mozgolom](https://forum.realdash.net/letter_avatar_proxy/v4/letter/m/b487fb/32.png) [@Mozgolom](https://forum.realdash.net/u/Mozgolom)\ **Post date:** [September 22, 2021, 9:42pm UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/12 "2021-09-22T21:42:37Z")
It still doesn’t work. The parameters are present in the can bus, but RealDash doesn’t see them. ---
**Author:** ![realdashdev](https://forum.realdash.net/user_avatar/forum.realdash.net/realdashdev/32/6_2.png) [@realdashdev](https://forum.realdash.net/u/realdashdev)\ **Post date:** [September 23, 2021, 5:09am UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/13 "2021-09-23T05:09:07Z")
Sorry to hear that. Without being able to test on actual device there is nothing much more I can do to help you. I know that especially Link ECU users are using RD Composite ID system successfully, so the system should work. ---
**Author:** ![Mozgolom](https://forum.realdash.net/letter_avatar_proxy/v4/letter/m/b487fb/32.png) [@Mozgolom](https://forum.realdash.net/u/Mozgolom)\ **Post date:** [September 26, 2021, 10:09pm UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/14 "2021-09-26T22:09:06Z")
Maybe there is some other way to see such data in RealDash? Without using composite ID. By the way, does the frequency of updating the parameter in the can bus matter? ---
**Author:** ![realdashdev](https://forum.realdash.net/user_avatar/forum.realdash.net/realdashdev/32/6_2.png) [@realdashdev](https://forum.realdash.net/u/realdashdev)\ **Post date:** [September 27, 2021, 5:35am UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/15 "2021-09-27T05:35:48Z")
You can use the CAN monitor option and highlight the interesting byte to see how its value changes when you have turn signal on. The frequency on which data is sent to CAN bus only affects how fast the updates to RealDash are. Otherwise it should not have any effect on interpreting the data. ---
**Author:** ![Mozgolom](https://forum.realdash.net/letter_avatar_proxy/v4/letter/m/b487fb/32.png) [@Mozgolom](https://forum.realdash.net/u/Mozgolom)\ **Post date:** [October 6, 2021, 9:41pm UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/16 "2021-10-06T21:41:58Z")
![](https://thumb.cloud.mail.ru/weblink/thumb/xw1/sSa9/aCGbuEkNn) That is my frame. But it does't work. Where is the mistake? ---
**Author:** ![realdashdev](https://forum.realdash.net/user_avatar/forum.realdash.net/realdashdev/32/6_2.png) [@realdashdev](https://forum.realdash.net/u/realdashdev)\ **Post date:** [October 7, 2021, 7:26am UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/17 "2021-10-07T07:26:56Z")
At least based on your screenshot your composite id on XML does not match on what you have on CAN monitor. I’m sorry, but its next to impossible to remotely trying to troubleshoot this sort of issues ☹ ---
**Author:** ![Mozgolom](https://forum.realdash.net/letter_avatar_proxy/v4/letter/m/b487fb/32.png) [@Mozgolom](https://forum.realdash.net/u/Mozgolom)\ **Post date:** [October 7, 2021, 7:34am UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/18 "2021-10-07T07:34:42Z")
Bytes 3 and 4 are constantly changing. These are identifiers. Bytes 5 и 6 these are DATA ---
**Author:** ![nfrenay](https://forum.realdash.net/letter_avatar_proxy/v4/letter/n/df788c/32.png) [@nfrenay](https://forum.realdash.net/u/nfrenay)\ **Post date:** [January 31, 2023, 12:33am UTC](https://forum.realdash.net/t/question-about-the-description-file/1035/19 "2023-01-31T00:33:40Z")
@Mozgolom: were you able to fix your issue? I have the same problem. Posted here: [https://www.realdash.net/forum/viewtopic.php?t=1866](https://www.realdash.net/forum/viewtopic.php?t=1866) Thanks.