interpreting "04142016_aaron_farm_manure" data

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Rifo Turs

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Jun 2, 2017, 8:27:21 AM6/2/17
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Hello,

I was going through the candroid-data-manure blog post and the corresponding data so that I can understand how the graphs were made.
I have a couple of questions. I would be glad if you can help me understand.

How did we process the raw data so that we got the below lines in the "04142016_aaron_farm_manure_can0.log" file.
Can you please tell me what the parts in red refer too? e.g  65306 is the PGN number

1460655422.9826 can0 27487966855184 32 547159599953 0 65306 8 3 0x000000000000ffff
1460655422.9831 can0 0 39 547159599953 0 65265 8 6 0xff9e0e0fffffffff
1460655423.0730 can0 3298711044353 3 547159599953 0 65496 8 6 0xfc007a1b081b238a
1460655423.0819 can0 0 39 547159599953 1 0 8 3 0x03c05dd1ffffffff
1460655423.0825 can0 0 39 547159599953 0 65265 8 6 0xff990e0fffffffff
1460655423.0831 can0 3298711044353 3 547159599953 0 65452 8 6 0x0000000000000000
1460655423.1730 can0 3298711044353 3 547159599953 0 65498 8 6 0xbf057611d500035c

Also for interpreting vehicle speed data I guess we need the J1939_73 standard? Am I right ?

It's because I came across this link which basically told me to get bytes 2 & 3 of PGN 65265 and multiply the result with 1/256
so for example with

1460655422.9831 can0
0 39 547159599953 0 65265 8 6 0xff9e0e0fffffffff

0x0e9e = 3742
3742 * (1/256) = 14.61 km/h  which makes sense with the graphs in the blog post
 

But for example for PGN 65266 I wasn't able to find how I should interpret data.

thanks a lot
rifo


Rifo Turs

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Jun 2, 2017, 8:56:30 AM6/2/17
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Sorry, it should have been we need the ISO 11783 standard for being able to decode general PGNs

2 Haziran 2017 Cuma 15:27:21 UTC+3 tarihinde Rifo Turs yazdı:

Yang Wang

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Jun 3, 2017, 2:42:39 PM6/3/17
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Hello Rifo,

1. For the CANdroid collected logs, the field definition is the following:

timestamp, CAN interface name, source name, source address, destination name, destination address, PGN, data length, priority, hex data

2. For the standard we are using, I believe it is ISOBUS 11783. It is based on the J1939 protocol but they are not exactly the same. The ISOBUS 11783 standard (only part of it is free) is available at: https://www.iso.org/obp/ui/#iso:std:iso:11783:-10:ed-2:v1:en

3. I have a spreadsheet that is available to our group for looking up PGNs but I am afraid I cannot share it here. I did find some information that contains how to parse PGN 65266:  www.dafulaielectronics.com/documents/dflsj1939bv1.pdf
The other place you could look is Pysobus's message definitions: https://github.com/FarmLogs/pysobus/blob/master/pysobus/message_definitions.csv.

Hopefully these answers help!

Regards,
Yang

Rifo Turs

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Jun 5, 2017, 4:25:15 AM6/5/17
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Hello Yang,

Thanks so much for your answer. They surely were of great help.

3 Haziran 2017 Cumartesi 21:42:39 UTC+3 tarihinde Yang Wang yazdı:

Rifo Turs

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Jun 6, 2017, 5:06:53 AM6/6/17
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Hello Yang,

I am going through the logs and try to understand the messages. I noticed that PGN 65265 (speed) comes at irregular intervals. For example, it comes many times per seconds for a while and then stops. After 20 seconds, it starts appearing again.

I think this is also valid for PGN 65266 too.  Is this normal? Can you please comment on this?

thanks
rifo


3 Haziran 2017 Cumartesi 21:42:39 UTC+3 tarihinde Yang Wang yazdı:
Hello Rifo,

dkhackney

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Jun 6, 2017, 6:23:17 AM6/6/17
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Rifo, 


PGN 652266 is labeled "Fuel Economy (Liquid)" and it transmits every 100ms.

If you are looking for fuel burn rate then you need PGN 652266 SPN 183.

SPN 183 is located in byte 1, bits 1-8 and byte 2, bits 1-8 of PGN 652266. 

The value is 0.05 Liters/hour per bit.



The PGN 65265 label is "Cruise Control/Vehicle Speed 1"

You need PGN 65265 & SPN 84.

The SPN 84 name is "Wheel-Based Vehicle Speed" and the description is "Speed of the vehicle as calculated from wheel or tailshaft speed."

SPN 84 is located in byte 2, bits 1-8 and byte 3, bits 1-8 of PGN 65265.

It transmits every 100ms. A once-per-second sample or a once-per-second average is a good value to use. 

The value is 1/256 km/h per bit.




You can also check for PGN 65096 & SPN 1862: "wheel based speed."

That transmits every 100ms.  A once-per-second sample or a once-per-second average is a good value to use.

SPN 1862 is in byte 1, bits 1-8 and byte 2, bits 1-8 of PGN 65096 

The value is 0.001 meters/second per bit.



If it's available on the bus, the GPS speed is more accurate. 

The GPS speed is PGN 65256 & SPN 517. 

The ISO spec on this PGN is "on request," so you may need to issue a request on the bus for this message. 

SPN 517 is in byte 3, bits 1-8 and byte 4, bits 1-8 of PGN 65256.

The value is 1/256 km/h per bit.




Doug

Rifo Turs

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Jun 6, 2017, 8:03:03 AM6/6/17
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Hello Doug,

Thanks a lot for your answer. I learned new PGN and SPN numbers :) yay!

About 65265, if I am not mistaken, there were missing periods of more than 20 seconds. I guess this is not normal.

I will try to look into other log files and see if there exists a similar behavior

rifo

6 Haziran 2017 Salı 13:23:17 UTC+3 tarihinde dkhackney yazdı:
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