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Old 01-27-2010, 10:11 AM   #11 (permalink)
Engineering first
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Originally Posted by orange4boy View Post
. . .
I have a mac powerbookG4 but all the software based programs I have seen are on PC . . .
On the side of the Graham scanner is an RJ-11 port and a pair of pins providing RS-232 signals. If you can get an RS-232-USB adapter, the Mac can read the stream of ASCII text. I just copy the stream to a file and use a Perl program to format it into a TAB delimited text. You may need a resistor to match the Rx signal levels depending upon the serial interface. I programmed the Graham scanner for the max, 6 data items, at the fastest rate, ~1.2 seconds for all six values.

There are a couple of undocumented aspects such as some data values return two elements (aka., MG1 torque also returns rpm.) Also, it works best if group 7, 1, and 2 are programmed for the six data items so when it powers up, you get these data values from the start. If you change the display slot, it also changes the fields streaming out the port. There is only a relative time-stamp and no data field identifier in the stream.

I've been working on a Perl program to read a GPS mouse, $50, in parallel with the Graham data. This lets me use the absolute time stamp from the GPS along with the ephemeris data mixed with the Graham data. But there is one word of caution.

The Graham data points are at separate data points, ~200 ms. apart, which is way to slow to track rapidly changing mechanical metrics. So I require any calculated data point like ICE power be used only when there are a minimum of two, and preferably three data points with the same or similar values. Otherwise you can calculate some impossible values like when the torque value comes from a different time interval than the rpm.

Bob Wilson

2019 Std. Range Plus Model 3 - 134 MPG3 || 2014 BMW i3-REx - 117 MPGe, 39 MPG
JuiceBox 40 Pro (240 VAC, 40 A), KHONS portable (120-240 VAC, 12-32 A)
Retired engineer, Huntsville, AL (five times AutoPilot saved.)
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