Newsgroups: comp.robotics
Subject: Data Acquisition Help re
From: andrew.jenkins@pcohio.com (Andrew Jenkins)
Path: brunix!sgiblab!swrinde!cs.utexas.edu!howland.reston.ans.net!usenet.ins.cwru.edu!ncoast!pcohio!andrew.jenkins
Distribution: world
Message-ID: <24.4763.2500.0NB2DC1C@pcohio.com>
Date: Thu, 10 Mar 94 19:38:00 -0500
Organization: PC-OHIO PCBOARD - Cleveland, OH - 216-381-3320
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<<  UN034123@WVNVMS.WVNET.ED to ALL   on    Data Acquisition Help re  >>


UL>Hi.  I am looking for anyone with information on the Tattle Tale Mark IV
UL>data logger or where I can find information on various data acquisition 
UL>techniques.  My project is to do on board data acquisition of a Formula
UL>racing car and am currently doing dyno testing of the engine.  Any help
UL>would be greatly appreciated. 

Hi Vic, nice to see another Tattletale user out there.

We use this device as the basis for our on-board computer at the 2.2 second 
Drop Tower at NASA-Lewis. We currently have about fifteen or so TT4/4As in 
operation, installed onto a daughter-board developed at Lewis for I/O 
buffering, precision reference, input protection, etc. They provide for 
control and data-acquisition for most of the microgravity experiments we 
drop at the Tower. They "do the job" for us most of the time.

BTW, forgive the format of my reply, I'm going on my memory, and my skills 
as a writer are poor at best. (I'm much better at using electronics than at 
describing:)

Okay, first question. Have you contacted Onset computers? (they're the ones 
who make the Tattletale.) I think you can get a manual for about $30 US. 
I'll have to get back to you for their phone, but you can probably find it 
in a Thomas's Register.

Second, the model 4 is relatively old. Are you in posession of one, or are 
you considering purchase? If you are purchasing, consider the model 4A.
Reasons to come.

Info!

The Tattletale model 4 is a single-board computer operating at 4MHz 
(optional 8MHz).

power: 	9 volt battery (best worked from 12V power source.
	note that there is no input protection (fusing, rev V protection)

16 digital I/O ports (TTL compatible  0,5V)

11-channel, 10-bit A/D. 
maximum aquisition rate is 100Hz (unless assembler code is written)
(note that 1 channel is internally hooked to an on-board thermistor for 
ambient-temperature measurement)

Operating System is BASIC (TTBasic to be exact)

Okay, so this is roughly what you're looking at. So...

The 4A comes standard with 

same power
same Digital I/O

8-channel, 12-bit A/D.
Max A/D speed is still 100Hz standard, except the version of TTBasic that 
is on this model allows for changing the "sleep" time between events.
This command is called "RATE"
This can allow you to sample faster (up to ~350Hz). 

Even faster data-acquisition rates *can* be achieved with both, but again, 
ASM code has to be written, as well as need for additional hardware.

The 12-bit A/D converter is one reason to get the 4A over the model 4, if 
you need greater resolution (of course at the cost of a few A/D channels!)
(note that the model 4A *can* still use the 10-bit converter.) 

The RATE command is the other reason. This command allows greater timing 
flexibility.

Cost for both is ~$400 in single-quantities.

(I don't work for Onset, my opinions are mine, bla bla bla...)

Regards,

AJ

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