Now, though, I must admit that I'm a more than a little perplexed. From the owner's manual, I read the following:
- p. 4: Buffer size... 32K
p. 5: In fast mode, the computer starts the ADC-2xx to collect a block of data into its internal memory. When the ADC has collected the whole block, the computer stops the ADC and transfers the whole block into computer memory.
p. 5: In slow mode, the ADC-2xx uses its internal memory as a FIFO: the computer can read values from the FIFO as soon as the readings are taken. In this mode, the ADC-2xx is running continuously, and there is no limit to the number of values that can be read.
- When using Picolog in fast block mode, as you are (previous post) the file size is resticted to the size of the buffer on the unit. The ADC-216 has a buffer of 32k when one channel is used and 16k for each channel when both are used.
- p. 7: Slow mode is used to collect samples at regular intervals over long periods. It is not currently implemented. adc200_get_single may be used until slow mode is available: it performs the same functions, but the user is responsible for timing when to take samples.
- This is the procedure for reading and displaying a block of data:
- open the ADC-200
select ranges until the required mV range is located
set AC/DC switches, channels, trigger and oversampling
select timebases until the required ns per sample is located
set the signal generator frequency (if required)
start the ADC200 running
wait till the ADC200 says that it is ready
stop the ADC200
transfer the block of data from the ADC
display the data
- Code: Select all
unsigned char * is_slow
- Code: Select all
So: Does slow mode exist? How much "slower" is it than fast mode? Or is there only fast mode, which requires turning on the ADC-216, sampling, turning off the ADC-216, downloading, turning the ADC-216 back on, etc? It's not clear what's meant by the "32K" buffer; it appears to be either 32 KBytes [which, at 16 bits, would be 16 KSamples], or 32 KSamples [which, at 16 bits, would be 64 KBytes], so it would appear that, in fast mode, the ADC-216 can only record the maximum claimed sampling rate of 333 KSamples per Second for only about 1/10th or 1/20th of a second, before sampling must stop and the unit must wait for a download to complete before it can begin sampling anew.
Could someone help me out? We don't need anywhere near the full 333 KSamples per second in our lab, or at least we don't need them just yet, but we will darn sure need more than one tenth of a second sample durations.
I hope we can get this cleared up, because, like I said above, the basic specs on the ADC-216 are very nice, as is the price point.