GPS info sent by CAN?

Information about using GPS units with motec devices

GPS info sent by CAN?

Postby Chris Wilson on Fri Aug 26, 2011 9:19 pm

I am unable to currently afford an ACL, so am persevering using a GEMS 1 gig CAN datalogger to log my M800 CAN messages. I have set up a custom CAN and can read GPS latitude and longitude, and GPS time by titching together the two 16 bit channels using this loggers data reading software's maths ability. I do not seem to be getting any data at all for satellites in view or GPS quality down the CAN BUS. I may be doing something wrong, but before I tear my hair out would you confirm this info is available by CAN from the M800 and what format I should expect it to be, with what sort of scaling required? Thanks. Maybe the upcoming CAN webinar could touch on stitching GPS 16 bit channels together, I alone know a few Motec users interested in getting a good grasp of this. Will the new ecu's be capable of sending 32 bit channels with no cludging?
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Re: GPS info sent by CAN?

Postby Holmz on Sat Aug 27, 2011 11:06 am

Chris Wilson wrote:I am unable to currently afford an ACL, so am persevering using a GEMS 1 gig CAN datalogger to log my M800 CAN messages. I have set up a custom CAN and can read GPS latitude and longitude, and GPS time by titching together the two 16 bit channels using this loggers data reading software's maths ability. I do not seem to be getting any data at all for satellites in view or GPS quality down the CAN BUS. I may be doing something wrong, but before I tear my hair out would you confirm this info is available by CAN from the M800 and what format I should expect it to be, with what sort of scaling required? Thanks. Maybe the upcoming CAN webinar could touch on stitching GPS 16 bit channels together, I alone know a few Motec users interested in getting a good grasp of this. Will the new ecu's be capable of sending 32 bit channels with no cludging?


Chris - I am using a 10-Hz GPS, through and STC (Serial To Can (RS0232)), and the #-sats come through fine.
You should be able to use a windows thing (maybe Hyperterm) and capture the data stream and see if that data is the RS-232 output from the GPS, then start follow the trail of crumbs from there.

This assumes that the GPS starts out on RS-232 and then goes to CAN.
If it starts out on CAN, then I guess you will need to find out what is being sent and if you are looking for the data in the right place.
Which GPS are you using?
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Re: GPS info sent by CAN?

Postby Chris Wilson on Sat Aug 27, 2011 6:34 pm

The Motec Garmin 5 Hz one that is feeding the M800 via the serial connection. Motec's i2 reads the satellite numbers and quality just fine, and I have set up channels in my Custom Can for them, too, but the GEMS logger doesn't show any data at all for those two. It's proving a bit of a nightmare, but needs must :) Thanks holmz!
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