DL1 Serial Refresh Rates

Turbo Synthesis
Posts: 6
Joined: Tue Mar 06, 2018 1:25 pm

DL1 Serial Refresh Rates

Postby Turbo Synthesis » Tue Mar 06, 2018 2:09 pm

Hi,

We have a DL1 logger hooked up to our own analysis software via the serial port at 115200 BAUD

Its taken a while to decode the serial stream but that's all up and working now, no real issues there, however we don't seem to be getting anywhere near the refresh rates that are set up in the logger.

For example the RPM input, which I've set to 25 Hz, only seems to refresh about every 2 Hz at best, more typically 1Hz. It also doesn't ever seem to report 0 RPM. If we kill the square wave at for example 50 Hz (3000 RPM) the DL1 continues to transmit the last valid tick time it had. Of course we could fix this with a simple timeout but that doesn't really feel like the best engineering solution.

All the analogue sensors are set to 5Hz but seem to update at 1Hz at best. Not a problem for a fuel or temperature input obviously but we are monitoring boost pressure, wastegate lift, VNT travel etc. and once per second is just not enough.

Pretty much all other serial outputs are turned off.

Its not a serial stream speed issue as the time stamp is updating at anything up to 50 Hz (hard to get an accurate reading but anyway its way fast enough).

We're pretty sure this isn't caused by anything in our software as we are seeing exactly the same refresh rates just hooking the DL1 direct to the RT Live Monitor.

Are we missing something?

Gareth (Turbo Synthesis Ltd)

racetec
Site Admin
Posts: 193
Joined: Thu Oct 27, 2005 12:02 pm

Re: DL1 Serial Refresh Rates

Postby racetec » Wed Mar 07, 2018 10:19 am

Hi,
The update rates are the maximum that you will see. They output at a default low background rate but otherwise only transmit up to the maximum rate if there is new data to display. So if you connect a sine wave generator to an analogue input you should see the output at the required rate, but if you connect to a fixed voltage you won't.

You are correct about the RPM input, if you have decoded the data stream you will know that the time reported is the time between the last two pulses. As such, if you suddenly turn off a high speed signal it will stop updating. There is no way that it can output a frequency of 0. You will need to implement a timeout for 0 rpm, we typically use a timeout of a second or two for this. Again, this will only give updates when the input value is changing up to the required rate.

Turbo Synthesis
Posts: 6
Joined: Tue Mar 06, 2018 1:25 pm

Re: DL1 Serial Refresh Rates

Postby Turbo Synthesis » Wed Mar 07, 2018 12:15 pm

Hi,

I did a bit of playing around with a variable frequency square wave and as you say the refresh rate massively increases once there is new data to display, it seems the DL1 is cleverer than we thought :D

Regards RPM, yes, of course, there is no way for it to output a frequency of zero. If I'd had a bit more sleep (you know what preparing race cars for a new season is like !) I would have realised that. A simple 1 second timeout does the trick.

Thank you for your help.

Gareth


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