![]() ![]() The channel status will change from OK to error, and the channel value will become the Error value defined on the JPIN. The parameter "J1939 error check" will have two effects if the parameter is outside the data range (bit value above >250 for a 1 byte parameter) Here are screenshots of the corresponding parameter in the IQAN program: If that is so, I think we can run without it. I guess my question at this point, is what exactly does "J1939 Error Check" do? It seems like the only thing it does is log errors if the J1939 data is outside acceptable limits. The other parameters that show error also have too-high values for the first several transmissions. ![]() As you can see, the first two transmissions show 254 in the location of the engine temperature parameter. I started the recording with power to the ECM off, and then turned the ignition on (ECM power-up) at 5 seconds. ![]() Here is a screenshot of an Analyze file, filtered to show only PGN 65262, engine temperature. I have more data now, and it seems to be pointing to a problem with the J1939 Error Check, as you suggested. I get inconsistent results with "don't care." Depending on the engine (we only use Caterpillar engines, but different sizes and age ranges), priority 3, 6, and "don't care" would sometimes cause the "J1939 Error" to show, and sometimes not. I experimented with different priorities, and with setting it to "don't care". It would be expected if the offset within the data field was set wrong on the JFIN, or if the lenght was wrong on the JPIN. The strange thing is, I don't see why you would get a "J1939 error" on these parameters. ![]() "J1939 not available" will not be put in the log, but "J1939 error" will. IQAN will use the status "J1939 not available" for the case where all bits are one, and "J1939 error" for all other cases where the parameter is outside of the error detection range. The special case is when all bits are 1, then that means the parameter is not available. The error range for J1939 values depends on the size of the parameter: About the priority on the JFIN, one recommendation is to use the 'don't care' option for this property, then the JFIN:s won't be filtered out based on priority, but only on PGN and Source Address.Ībout the J1939 error, you will get this status on a JPIN if it uses the property J1939 error check, and the bit-value is outside of the standard error detection range for J1939. ![]()
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December 2022
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