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DT80 series 2 fast sample rate

Hi
I am logging 2 Pressure transducers (mV) and 2 digital counters on a DT80 series 2.
I have set the scan rate to 200mS. I have found that the DT
on about every 7th scan there is about 400-500mS interval
I know these are not high speed loggers but are there any settings I could use to speed up the readings. I only need to scan at the fast rate for about 20seconds during testing
I have tried setting auto calibrate to larger interval but this did not seem to change things
Also setting to 1000Hz
Thanks

Hi I am logging 2 Pressure transducers (mV) and 2 digital counters on a DT80 series 2. I have set the scan rate to 200mS. I have found that the DT on about every 7th scan there is about 400-500mS interval I know these are not high speed loggers but are there any settings I could use to speed up the readings. I only need to scan at the fast rate for about 20seconds during testing I have tried setting auto calibrate to larger interval but this did not seem to change things Also setting to 1000Hz Thanks

I found similar a few years ago trying to measure one mA reading at 100ms

The manual has a section on "How fast can I log data?" under "How data and alarms are stored" that may help you understand what you can change to assist you

How Fast Can I Log Data?
The time taken to log one data record for a schedule is essentially the sum of:
.
measurement time – the time taken to acquire data for all channels in the schedule. For digital channels and
channel variables (CVs) this is close to negligible; for analog measurements it can be significant (normally at
least 30ms per measurement); for serial channels it can be very significant (possibly many seconds for SDI-12,
for example)
.
processing time – the time taken to perform any linearization or other data manipulation calculations that may
be required
.
communications time – the time taken to format and return real time data values over a communications link
.
logging preparation time – the time taken to generate a data record to be logged
.
file system time – the time taken to physically write the data to the internal flash disk or external USB device
The first three of these depend on the job and the logger settings. We can largely eliminate them by defining a job
consisting only of CVs, and switching off real time data returns (/r).
As discussed above, there is a storage overhead associated with each data record; hence 20 records each with one
channel will require more space than one record with 20 channels. The same goes for time – there is a fixed time
overhead in preparing a data record, plus a variable time which depends on the number of channels.
The following table list some typical logging rates:
Schedule
Description
Logging rate
/r RA("B:") 1CV
log one CV to internal memory
55 records/s
/r RA("B:") 1..20CV
log 20 CVs to internal memory
40 records/s
/r RA("A:") 1CV
log one CV to 512M USB device
4 records/s
/r RA("A:") 1..20CV
log 20 CVs to 512M USB device
3 records/s
There may be some variation in performance depending on the brand and capacity of the USB device, but in general
logging to USB will be around an order of magnitude slower than logging to the internal flash memory.

I found similar a few years ago trying to measure one mA reading at 100ms The manual has a section on "How fast can I log data?" under "How data and alarms are stored" that may help you understand what you can change to assist you How Fast Can I Log Data? The time taken to log one data record for a schedule is essentially the sum of: . measurement time – the time taken to acquire data for all channels in the schedule. For digital channels and channel variables (CVs) this is close to negligible; for analog measurements it can be significant (normally at least 30ms per measurement); for serial channels it can be very significant (possibly many seconds for SDI-12, for example) . processing time – the time taken to perform any linearization or other data manipulation calculations that may be required . communications time – the time taken to format and return real time data values over a communications link . logging preparation time – the time taken to generate a data record to be logged . file system time – the time taken to physically write the data to the internal flash disk or external USB device The first three of these depend on the job and the logger settings. We can largely eliminate them by defining a job consisting only of CVs, and switching off real time data returns (/r). As discussed above, there is a storage overhead associated with each data record; hence 20 records each with one channel will require more space than one record with 20 channels. The same goes for time – there is a fixed time overhead in preparing a data record, plus a variable time which depends on the number of channels. The following table list some typical logging rates: Schedule Description Logging rate /r RA("B:") 1CV log one CV to internal memory 55 records/s /r RA("B:") 1..20CV log 20 CVs to internal memory 40 records/s /r RA("A:") 1CV log one CV to 512M USB device 4 records/s /r RA("A:") 1..20CV log 20 CVs to 512M USB device 3 records/s There may be some variation in performance depending on the brand and capacity of the USB device, but in general logging to USB will be around an order of magnitude slower than logging to the internal flash memory.

thanks very much Groggan for the detailed explanation
I will play around with things
but basically I store data to the DT flash drive
I also return the data to a computer as I have written graphic software to view graphs in near real time.

thanks very much Groggan for the detailed explanation I will play around with things but basically I store data to the DT flash drive I also return the data to a computer as I have written graphic software to view graphs in near real time.

Hi litters95,

If you see a different timestamp randomly appear in your data, it usually relates to the internal calibration process. It will automatically readjust the logger parameters depending on any internal temperature variation.

You can disable the internal calibration by setting the switch K to OFF or increasing the detection level by setting parameter P0 to 5 uV (or greater, default is 3 uV).

@Groggan thanks for the explanation.

Best regards,
dataTaker Expert

Hi litters95, If you see a different timestamp randomly appear in your data, it usually relates to the internal calibration process. It will automatically readjust the logger parameters depending on any internal temperature variation. You can disable the internal calibration by setting the switch K to OFF or increasing the detection level by setting parameter P0 to 5 uV (or greater, default is 3 uV). @Groggan thanks for the explanation. Best regards, dataTaker Expert
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