The Emerald "spS" data block

Rough and ready notes on the "spS" Emerald data block. Please let me know if you have any further information.

Sent at ~ 3 Hz. Only seems to be sent when the engine is running.

Characters (spaces are for readability only; they are not in the data)
SOH (ASCII 0x01) Start of header.
spS Identifies the type of block.
RS (ASCII 0x1E) 0 aacc Record 0.

These are both resistance rather than voltage readings, and hence are the opposite way to what you might expect.

aa: air temperature. Number gets smaller as the air gets hotter.
cc: coolant temperature. Number gets smaller as the coolant heats up.

cc typically starts few degrees lower (numerically higher) than aa.

Need to correlate with Emerald logging to determine the mapping between value / temperature.
RS 1 pppp pppp: barometric pressure. Not sure of the units. Always 0x4018, possibly because I don't have a MAP sensor?
RS 2 aaaa aaaa: Aux 1 input? Typically 0001, 0005.
RS 3 aaaa aaaa: Aux 2. Always 0x03FF, because not connected?
RS 4 aabb
I think it's aabb, e.g. changes from 9442 to 9342.
RS 5 .... e.g. 001A, 0019, FFFF, 0000.
RS 6 .... Typically 0000 / 00FF.
RS 7 ....
RS 8 .... Always? 0000.
RS 9 .... Typically 0001 / 0005.
RS a .... Always? 0200
RS b .... Always? 4802.
RS c .... Always? 0000.
RS d .... Always? 0000.
RS e .... Always? 400A.
RS f .... Always? 0000.
RS g .. Always? 10.
RS h .. Always? 3D.
RS i rrrr ??? rrrr: Maximum ever revs. Appears to be the same as block "StS" i rrrr.

Always? 1D20.
EOT (ASCII 0x04) End of transmission.
SPe Indicates the end of this block.

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This page is It was first published on Thursday 2 December, 2004 and last updated on Thursday 2 December, 2004.