J1939 Decode

2020-02-27T13:51:46.356000Z

With J1939 a 29 bit identifier is used.
This contains e.g. the Priority, PGN, and Source Address (SA).

To filter these from the Identifier you could use something like:
SA := _29bitId AND 16#FF;
PGN := SHR(_29bitId,8) AND 16#FFFF;
PRIO := SHR(_29bitId,24);

If you run this with your 29bit identifier (16#054c00ff), you will get as result for the PGN 19456.

The other 8 bytes represent the data (SPN) which relates to the PGN.

I'm not a J1939 expert, so please correct me if I'm wrong.
Anyway I hope this helps.

J1939 Decode

2020-02-27T13:51:46.154000Z

I found some new information:
If I try to decode the first message I get the following:

message priority = 1
EDP=0
Data Page=1
PDU=76 since PDU is less than 240 the next 16 bits are for source and destination
Destination = 0
Source = 255
PGN=19456

Am I on the right track? If so, why is the destination 0? How can I determine what PDU 76 means?
Are there PGN messages that I can use to create my own custom hardware?

J1939 Decode

2020-02-27T13:51:45.635000Z

I'm working on decoding a few Canbus messages. I know what they do but I don't know what they mean.
I have a few IO modules and the controller will send a message of:

0x054c00ff 01 a1 20 00 00 00 00 84 -This message will turn on output#1
0x054c00ff 01 a1 10 06 01 32 00 84 -This message will turn on output#1 with PWM of 50%
0x054c00ff a0 a1 60 01 00 80 00 02 -This message will request status and the module will reply with 0x054c0001 a1 a0 00 46 02 00 00 00

Can someone shed some light on what these numbers represent?

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