Reply With QuoteCan't you just export the data to Excel and get rid of the data you don't want?
Originally Posted by Jitterbug
Master
I have recently bought an Omega PX409 USB data logger. The software that comes with the is crap and will only let you sample at a rate of once a second, I want somewhere between 4 and 10 readings a second.
Their technical support is decidedly useless telling me their is no alternate software, even though the thing comes with drivers for LabView and Visual Studio / DotNet.
Labview looks like labview will do what I want without too much trouble but it seems overkill when all i want to do is record pressure/time, in approx 1 min blocks, and put this into excel for analysis and to draw graphs.
here are the drivers and command references etc:
ftp://ftp.omega.com/public/DASGroup/products/PX409-USB/
I am hoping someone smarter than me will know something about this and can point me in the direction of a simple solution?
TopicToaster
Can't you just export the data to Excel and get rid of the data you don't want?
Master
The problem is that i dont have enough data, not too much. I need a sample rate of between 4 and 10 readings a second, the program that came with it only gives 1 reading a second.
Fossicker
I would assume that the readings from the software are averaged over the 1 second sample. So sampling faster would not add any information if you are going to average into 1 min blocks anyway?
Master
My initial description might not have been the best, over that one minute period I need to see what the pressure is every 0.1 second.
It is for the bench testing of relief valves to confirm at what pressure they are opening.
Fossicker
A quick google suggests the bandwidth of the sensor is DC to 3Hz, meaning that the data sampled this fast would not really add any meaning? It is possible i looked at the wrong thing or there is more information regarding freq response somewhere?
Master
even 3hz would be a big improvement to the 1Hz the software will let me work to...
Master
The UK omega site specifies
"Max. Read Rate: 1 sample/second (using Omega software)"which implies software could be the limiting factor. Given it is an analogue signal to the compluter the response of the transducer and processing power of the PC should be the only limiting factor.
The non-USB model that logs to memory will take up to 1000 readings a second.
Fossicker
No the A to D conversion happens on board the transducer.
I assume this is the thing you are talking about USB Pressure Transducer PX409USB
You could write a program to talk to the device through the serial interface, and see if polling the device gives you a greater sample rate than 1Hz?
YarnMaster
SubscriberOn your link is some supplied C# sample code for interrogating the device. You are going to have to use it or modify it to change the sampling rate.
If you look at that code you will find in method "start_button_Click" the relevant piece of code to modify. (I think)
// Parse the wait time between data collection, and put the while loop to short sleeps while waiting.
int waitTime = 0;
int.TryParse(waitTime_textBox.Text, out waitTime);
int count = 0;
do
{
Thread.Sleep(50);}
Application.DoEvents();
count++;
while (count < waitTime * 20);
The 'Sleep' parameter and the value of 'waitTime' have some influence on how fast the software samples data from the device. I think
The value of 'waitTime' is being set in a 'Textbox', ie it is a value you type in when you run this code so you may be lucky and not need to modify anything at all - again I think.
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