datalogging with robotc

[rbnnxt]

I should probably post this to the robotc board, but can anyone help with this problem. robotc has a system variable nDatalogSize which shows the size of memory allocated to store datalog files.
The sample program supplied with robotc suggests that you can alter its value. e.g.
const int kDatalogSize = 2000;
.....
nDatalogSize = kDatalogSize;

However I find that the value is constant at 1665, and I can neither increase nor decrease this. I have seen other discussions which show the value at 4665 which is considerably higher. Is it possible to change the size? I appreciate there will be a maximum set by the available allocated memory.

[mightor]

You did post this on the ROBOTC forums

Anyway, I've never managed to really use the ROBOTC datalogging stuff. It's always been trouble for me. I usually roll my own. What are you looking to datalog?

- Xander

[aswin0]

Hi,

You can also try my NXT2excel utility. It allows you to send data over bluetooth to excel and takes away the burdon of writing and downlading log files. The best thing is that you can (graphically) analyse your data while your program is running.
You'll find NXT2excel on my blog.

[rbnnxt]

You did post this on the ROBOTC forums

Eventually. I joined the board but it took ages to send the confirmation email. Whilst waiting I posted here, then I also posted it there! It appears to be down this morning so I can't even see if there are any replies!

Anyway, I've never managed to really use the ROBOTC datalogging stuff. It's always been trouble for me. I usually roll my own. What are you looking to datalog?

- Xander

Well I've made the Dazzlingly Didactic Dropper from the Cambridge Course featured here http://mi.eng.cam.ac.uk/IALego/
Unfortunately I don't have access to MATLAB so can't use the RWTH NXT toolbox. I have got the system working using NXT-G programming, but the data logging isn't fast enough. I have rewritten the datalogging using robotc and have dumped captured files to excel and obtained reasonable graphs. However I came across the problem of the apparently fixed datalog size, hence the post.
From a purely mechanical point of view it is a fun project to build. I have also built the clock project and hope to have a look at the others.

[rbnnxt]

Hi,

You can also try my NXT2excel utility. It allows you to send data over bluetooth to excel and takes away the burdon of writing and downlading log files. The best thing is that you can (graphically) analyse your data while your program is running.
You'll find NXT2excel on my blog.

Thanks for this. I'll take a look. As you say, it is tedious uploading the robotc datalog files, converting them to excel and then separating the data so you can plot graphs.