Hello,
Currently we have several DT800s that we use for data logging, which run at 4 Hz. However, I would like to use the burst feature of the DT800 to record current and voltage characteristics of electric motors and motor controllers.
Ideally, I would like to sample at rates of 1 kHz to 10 kHz for periods of a couple of seconds up to several seconds. I have a couple of questions:
(1) The actual sampling speed of the DT800 seems to be half of what I've specified by using the BURST command. I understand that I can sample up to ~65000 fundamental samples. I'm using the VNC command (one fundamental sample) to read analogue channel 1 for a value between -10 to 10 volts (positive to "+" and negative to "-" are hooked into the channel).
I'm using a function generator to generate a 1 kHz sine wave, and have the BURST command set to 10 kHz, however, when I analyze the data, I find that I'm getting exactly a 5 kHz sampling frequency. I have set the number of fundamental readings to acquire to 30000, so that I can get about 3 seconds worth of data. However, theoretically, i should be able to set it to 60000 to get six seconds worth of data.
However, when I do this, I get the "too many samples requested for burst" error. This is strange, because in the literature, it states that VNC uses 1 fundamental sample, whereas V uses four.
The ADC runs at 100 kHz, which means that I should be able to sample V at 25 kHz and VNC at 100 kHz. But in the literature, it states that VNC maxes out at 50 kHz.
Why? I even tried putting two lines (one after the other) with the 1VNC command in the program, but the sampling frequency maxed out at approximately 6 kHz (remember it was set to 10 kHz in the BURST command).
(2) My other question has to do with unloading information from the datataker when capturing these bursts. I would like to capture the data to a compact flash card and then place that in my computer and examine it there.
In addition, I'd like the possibility of keeping my computer communicating to the datataker through a terminal program (i.e. DeTransfer). However, I have the following problems: when I am connected to the datataker with a serial cable, it will automatically start sending data via the serial cable when I trigger the burst mode.
So, I tried setting a 1 minute timeout, started the program, issued a halt command (while it was running), disconnected the serial cable and triggered the burst capture.
After the burst has timed out, i checked the datataker's internal memory by hooking up the serial cable again and I can not find the data.
In addition, I have also tried NOT communicating, but installing a formatted CF memory card in the datataker (both while logging, of after logging) expecting the data either to be written to the card, or to be transferred to the card afterwards. In each case, there was no burst data available on the card, nor was it inside the datataker's internal memory.
Finally, I issued the /r command to the datataker, so that it would NOT send data over the serial cable, but it still did. I used a DO command and put it in the program, but then realized that DO commands are NOT executed in Burst mode.
So, I just sent the /r command (and also tried /R just to make sure that I didn't have it backwards) across the terminal. Again, no luck.
Sorry for the long post - I just wanted to be as clear as possible. I'm close, but it's not quite doing what I need it to do. The goal is to install the datataker onto an electric motor or controller and watch how the voltage and current change.
I am trying to use the LEVEL command to trip the burst mode so that I can have about 25% of the samples before the trigger and 75% after the trigger (or something along those lines). Any help would be greatly appreciated.
Thank you.
Knolly
Hello,
Currently we have several DT800s that we use for data logging, which run at 4 Hz. However, I would like to use the burst feature of the DT800 to record current and voltage characteristics of electric motors and motor controllers.
Ideally, I would like to sample at rates of 1 kHz to 10 kHz for periods of a couple of seconds up to several seconds. I have a couple of questions:
**(1)** The actual sampling speed of the DT800 seems to be half of what I've specified by using the BURST command. I understand that I can sample up to ~65000 fundamental samples. I'm using the VNC command (one fundamental sample) to read analogue channel 1 for a value between -10 to 10 volts (positive to "+" and negative to "-" are hooked into the channel).
I'm using a function generator to generate a 1 kHz sine wave, and have the BURST command set to 10 kHz, however, when I analyze the data, I find that I'm getting exactly a 5 kHz sampling frequency. I have set the number of fundamental readings to acquire to 30000, so that I can get about 3 seconds worth of data. However, theoretically, i should be able to set it to 60000 to get six seconds worth of data.
However, when I do this, I get the "too many samples requested for burst" error. This is strange, because in the literature, it states that VNC uses 1 fundamental sample, whereas V uses four.
The ADC runs at 100 kHz, which means that I should be able to sample V at 25 kHz and VNC at 100 kHz. But in the literature, it states that VNC maxes out at 50 kHz.
Why? I even tried putting two lines (one after the other) with the 1VNC command in the program, but the sampling frequency maxed out at approximately 6 kHz (remember it was set to 10 kHz in the BURST command).
**(2)** My other question has to do with unloading information from the datataker when capturing these bursts. I would like to capture the data to a compact flash card and then place that in my computer and examine it there.
In addition, I'd like the possibility of keeping my computer communicating to the datataker through a terminal program (i.e. DeTransfer). However, I have the following problems: when I am connected to the datataker with a serial cable, it will automatically start sending data via the serial cable when I trigger the burst mode.
So, I tried setting a 1 minute timeout, started the program, issued a halt command (while it was running), disconnected the serial cable and triggered the burst capture.
After the burst has timed out, i checked the datataker's internal memory by hooking up the serial cable again and I can not find the data.
In addition, I have also tried NOT communicating, but installing a formatted CF memory card in the datataker (both while logging, of after logging) expecting the data either to be written to the card, or to be transferred to the card afterwards. In each case, there was no burst data available on the card, nor was it inside the datataker's internal memory.
Finally, I issued the /r command to the datataker, so that it would NOT send data over the serial cable, but it still did. I used a DO command and put it in the program, but then realized that DO commands are NOT executed in Burst mode.
So, I just sent the /r command (and also tried /R just to make sure that I didn't have it backwards) across the terminal. Again, no luck.
Sorry for the long post - I just wanted to be as clear as possible. I'm close, but it's not quite doing what I need it to do. The goal is to install the datataker onto an electric motor or controller and watch how the voltage and current change.
I am trying to use the LEVEL command to trip the burst mode so that I can have about 25% of the samples before the trigger and 75% after the trigger (or something along those lines). Any help would be greatly appreciated.
Thank you.
Knolly
