Hello,
I would like to know more about the equipment
cFP-1804, cFP-1808
http://sine.ni.com/nips/cds/view/p/lang/de/nid/202527
http://sine.ni.com/nips/cds/view/p/lang/de/nid/202210
cFP-RTD-122
http://sine.ni.com/nips/cds/view/p/lang/de/nid/11588
8 inputs
or
cFP-RTD-124
http://sine.ni.com/nips/cds/view/p/lang/de/nid/11589
8 inputs
connected to a Windows PC running Labview.
We need either 4 (option1) or 10 channels (optioin2) of temperature data, with a maximum sample rate of 10 Hz for each channel,
for a test bed for electric motors in a laboratory. The data aquisition time is 24 hours, we need a "continous data recording" mode both with the data aquisiton driver/hardware and with Labview. The Labview PC itself controls the motor and brake system, by special devices connected by GPIB bus.
One offer by a test bed manufacturer is to use this Fieldpoint equipment with serial connection,
while we would prefer
* either to wait some months and take a cDAQ solution after the forthcoming and announced release of the drivers for NI 9217
RTD Module for the cDAQ platform
* take an Ethernet TCP/IP connection for the communication between .cFP-1804 and Labview PC.
Well why do we want to use the "dumb" Fieldpoint backplane ? It is the
cheapest Fieldpoint solution and the compiled Labview software of the test bed manufacturer does not
support other devices so far. Alternatively we just buy the testbed and write the Labview software by ourselves.....
We know with cDAQ, we might use a "hardware loop" so that the sample speed is guaranteed by the cDAQ device, and that Labview runs in a loop which is just activated after a block of data arrived.
QUESTIONCan the dumb fieldpoint backplanes cFP-1804, cFP-1808 with the temperature input modules cFP-RTD-122,
cFP-RTD-124 do that "hardware loop" with sample rates, guaranteed by the hardware, up to each 10 Hz too, for 4 or 10 channels?
Indeed, are there free DAQmx drivers for accessing the data by cFP-1804, with all usual options like "continous recording" of data, or is there a different way to get the data ( direct VI devices which can read the serial port or TCP/IP port ) ?
We were told so far, that we must use the "Timded Loop", so that Labview must guarantee the sampling rate.
And that Labview must call any data from the Fieldpoint devices, i.e.that it must call for a temperature A/D conversion for each requested data.
Is that true ? ( of course with very-cheap USB data aquisition boxes like 6009 this is true.) .It would be a burden for Labview !???!
And if so, does measuring 10 channels cost more time than measuring 1 or 4 channels ?
Is the (serial) transfer the typical bottleneck of the Fieldpoint system if used for data aquisition ? Is the built in TCP/IP Ethernet solution so much better ?
QUESTIONWhat is the maximum sample speed I can get with
dumb fieldpoint backplanes cFP-1804, cFP-1808
with the temperature input modules cFP-RTD-122,
cFP-RTD-124, and how is speed affected by the number of channels ?
As this Fieldpoint device might be the base for further test experiments with need for higher sample speeds.
For comparison cDAQ with forthcoming drivers for NI9217 module supports up to 100 Hz/Channel, AFAIK.
So 4 channels with 100 Hz, or 10 channels with 100 Hz should be no problem...
QUESTION
Can you recommend to use the Fieldpoint system and NOT the cDAQ system and NOT a PCI card system,
if yes by what reason ?
And can you really recommend Fieldpoint for our problem ?
QUESTION
Is there a comparison chart about the maximum sample / transfer rates of
NI PCI cards
NI cDAQ
NI Fieldpoint
, with the number of used channels as parameter ?Sincerely
Rolf Hemmerling
Message Edited by hemmerling on 01-11-2007 12:08 AM