SAE J2716 SENT data protocol plugin

[nimic]

Hello

The following lines are an output from a data log of an automotive mass air flow sensor:

Ch   Len  Typ   Delta t                 Time                   Data
00   08   00    00:00:00.000.819.200    00:00:00.428.572.160   C3 EB DD 41
00   08   00    00:00:00.000.819.200    00:00:00.429.391.360   03 EB DD 41
00   08   00    00:00:00.000.819.200    00:00:00.430.210.560   03 EB DD 41
00   08   00    00:00:00.000.816.640    00:00:00.431.027.200   03 EB DD 41
00   08   00    00:00:00.000.819.200    00:00:00.431.846.400   03 EB 9D 40
00   08   00    00:00:00.000.819.200    00:00:00.432.665.600   03 EB DD 41
00   08   00    00:00:00.000.819.200    00:00:00.433.484.800   03 EB DD 41
00   08   00    00:00:00.000.816.640    00:00:00.434.301.440   03 EB ED 48
00   08   00    00:00:00.000.819.200    00:00:00.435.120.640   83 EB DD 41
00   08   00    00:00:00.000.819.200    00:00:00.435.939.840   83 EB DD 41
00   08   00    00:00:00.000.819.200    00:00:00.436.759.040   03 EB DD 41
00   08   00    00:00:00.000.819.200    00:00:00.437.578.240   03 EB DD 41
00   08   00    00:00:00.000.816.640    00:00:00.438.394.880   03 EB ED 48
00   08   64    00:00:00.000.000.000    00:00:00.438.394.880   0C 000 25
00   08   00    00:00:00.000.821.760    00:00:00.439.216.640   83 EB DD 41
00   08   00    00:00:00.000.816.640    00:00:00.440.033.280   83 EC 2D 4A
00   08   00    00:00:00.000.819.200    00:00:00.440.852.480   C3 EB DD 41
00   08   00    00:00:00.000.819.200    00:00:00.441.671.680   83 EB AD 49
00   08   00    00:00:00.000.816.640    00:00:00.442.488.320   83 EB DD 41
00   08   00    00:00:00.000.819.200    00:00:00.443.307.520   83 EC 2D 4A
00   08   00    00:00:00.000.819.200    00:00:00.444.126.720   03 EB DD 41

Importing this into DIAdem shows several obstacles:

a) Data delimiter is not <Space> but <Space><Space><Space>. Is it possible to use more than 1 character in the delimiter definition in File.Formatter?

b) Time format is hh:mm:ss.fff.fff.fff and will try to track down 10 ns.

c) Data are string literal hex numbers separated by <Space>.... :-((

I do fear that those of you who work in automotive industry are likely to come past the "single edge nibble transmission" protocol some day or other.

Once the data have been imported correctly, the next step will be to split the Data DWord into nibbles to get the 2 channels, one 14 bit one 10 bit length, out of the data. They are hidden according to following rule:

Bit

1 2 3 4|5 6 7 8 |9 10 11 12|13 14 15 16|17 18 19 20|21 22 23 24|25 26 27 28|29 30 31 32

STatus |MSN Ch1 |2ndN Ch1  |3rdN Ch1   |LSN/2|LSN/2|MidN Ch2   |MSN Ch 2   |CRC N

1 nibble= Status

2-4 nibble = Bit 14 - 3 of Channel 1

5 nibble = 2 bit of Ch 1, bits 2 and 1 follwed by 2 bits of Ch 2, bits 2 and 1

6 nibble = Bit 6-3 of Ch 2

7 nibble = Bit 10 - 7 of Ch 2

8 bit = Checksum

The last bit of extracting a 14 and 1 10 bit channel are independent of the file format. If the data came in decimal, it would still need covnersion to Byte and nibble resorting.

Awkward, isn't it?

Anyway, I am sure DIAdem can do it, given that a number of bit- and byte-manipulating functions are available.

Thanks for contributions to this thread.

Michael

[nimic]

Well, after reading some post regarding hex strings, I found the following solution:

'gather bytes from 4 channels and convert to LONG (Thanx to Brad Turpin...)

Call Calculate("CH(""Data"")=CLng(""&H"" & Mid(Ch(""[1]/Byte1"")&Ch(""[1]/Byte2"")&Ch(""[1]/Byte3"")&Ch(""[1]/Byte4""),2,6))",NULL,NULL,"") '.

' Extract fast channel 1: Logical AND for 14 bit from start and shift  10 bit to right

Call Calculate("CH(""Flow"")=SHR(AndB(Ch(""[1]/Data""),16776192),10)",NULL,NULL,"") '

' Extract fast channel 1: Logical AND for 2 bit from the middle, 4 bit from nibble 4 and 4 bit from nibble 5 and rearrange

' convert to temperature with gain 0.25 and offset 53.15

Call Calculate("CH(""Temp"")=(SHR(AndB(Ch(""[1]/Data""),768),8) + + SHR(AndB(Ch(""[1]/Data""),240),2) + SHL(AndB(Ch(""[1]/Data""),7),6))/4-53.15")

[Brad_Turpin]

Hi Michael,

First off, DIAdem 2012's datetime channels use a DBL representation and can only store down to a 10th of a millisecond, so even if you could write the DataPlugin to parse the unusual "ss.fff.fff.fff" format, DIAdem couldn't accept the last "ff.fff" fractional second information.  I think your best bet is to declare the datetime channels and also the Hex channels as DirectAccessChannels of data type = eString and then use DIAdem commands to transform these string channels into numeric/datetime channels.  You've already found the Hex-->Integer approach with the Calculator.  You will probably need to break the datetime information into 2 new data channels.  I would recommend one datetime channel with resolution down to "ss.ffff" plus another numeric channel with elapsed relative time in seconds.

If this is a standard Bus Log (CAN) file, perhaps you could use the Bus Log Converter to handle these onerous issues better.

Brad Turpin

DIAdem Product Support Engineer

National Instruments