topic Re: DasyLab & BlueSentry wireless DA in DASYLab

DasyLab & BlueSentry wireless DA

estragon — Fri, 06 Mar 2009 12:49:59 GMT

Hey!

I'm having a problem using DasyLab7 with Rovingnetworks' Bluesentry (Bluetooth wireless AD sensor). DasyLAb's Recorder displays the acquired data in uneven time intervals.

Bluesentry is connected with the PC over Bluetooth, represented as a serial COM port, i.e. serially connected through RS232.

The settings of the port are: baud rate 9600, data bits 8, stop bits 1, no parity, without handshake.

I used the RS232 input module in Dasylab to acquire data from Bluesentry's analog input.

RS232 input module settings:
data format: "\x0D\x0A" 4ah which is used to parse out the value for the 1st channel from a string of the form ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD (where ABCD represents the values given in the fast ascii format)
data request command and data acknowledge string are not set
start command: $d0200 8 c
One sample per data point
header size: 0 Char

active channels: no. 0

The problem is that no matter which transfer rate I set (using the delay commands in the Start command settings area), the sample times of a certain channel change in a wide range, without any pattern.

What do you advise I should do to get the samples in even time intervals according to the given frequency, if it's possible? Are there some limits?

Other settings include :
Experiment setup:
SampleRate: 10kHz
BlockSize: auto select
synchronized through PC clock, with the driver buffer set to 16384KByte and continous acquisition mode

It would be great if somebody can help me to find the correct settings.

Thank you in advance,
Vida

Re: DasyLab & BlueSentry wireless DA

CJ_Butler__DASYLab_Pro — Fri, 06 Mar 2009 16:10:59 GMT

I would first try to REDUCE the sample interval that you set in the RS232 Input Options dialog.

If there is no data request command, and you're just reading the inputs, then you should only expect DASYLab to read 1 sample/second or less. The parse string includes a search string, which slows down an already slow module.

Don't expect DASYLab's RS232 to be fast. It will never do better than 10 samples/second, and is more reliable at 1 sample/second or slower.

Message Edited by CJ Butler -- DASYLab Pro on 03-06-2009 11:10 AM

Re: DasyLab & BlueSentry wireless DA

estragon — Mon, 09 Mar 2009 09:30:52 GMT

Thanks CJ for your reply! (:

Is there some module I could use instead of the RS232 that could read the samples faster?

Greets, Vida

Re: DasyLab & BlueSentry wireless DA

TomRizzo — Mon, 09 Mar 2009 12:47:26 GMT

Vida

In the market there are many products that provide wireless to analog signal or wireles DAQ systems.

It depends your application.

Tom

Re: DasyLab & BlueSentry wireless DA

CJ_Butler__DASYLab_Pro — Mon, 09 Mar 2009 13:22:40 GMT

You could write your own module to handle it. The generic RS323 and ICOMS modules were not written for high speed. Anything faster needs buffering and better handling, and, for a new device, you need to ask them for a driver or write your own.