Question on Sampling Rate with M-Series 6220 and SCC-RTD01 PT100-modules

[hemmerling]

Hello,

I need to select a PT100 temperature measurement device, which can easily do 10 samples/second, for 10 channels.

So I was frustrated that the
NI PCI 4351
http://sine.ni.com/nips/cds/view/p/lang/de/nid/1867
just has a scan frequency of  ( 9,7 Hz / number of channels ) in Multichannel Mode.

Now with affordable M-Series,
does this work ?

NI PCI-6220
http://sine.ni.com/nips/cds/view/p/lang/de/nid/14130

connected with a cable

SHC68-68-EPM

http://sine.ni.com/nips/cds/view/p/lang/de/nid/203378

to a SC2345 box
http://sine.ni.com/nips/cds/view/p/lang/de/nid/10778

which shipps  5 x SCC-RTD01
http://sine.ni.com/nips/cds/view/p/lang/de/nid/12311

So according to my calculation,
250 KSamples/sec also in Multichannel Scan Mode,
250 KSamples/s : 10 channels = 25 KSamples / s = 25.000 Samples / s

is factor 1000 away from the 10 Hz I need.
Do I calculate right,
and are there any speed drawbacks
** by the cable
** by the RTD devices which connect to the PT100 resistors ?
that I don´t realize ?

Or was it JUST the 4351 which makes me crazy... ?

[hemmerling]

I don´t that I have 25.000 samples / second with the RTD modules,

if both Fieldpoint and cDAQ systems have VERY LITTLE sample rates for both

Thermo elements
and
RTDs

So question is: What effective sample speed do I get with M-series analog-in cards, for temperature measurement with RTD module

SCC-RTD01
?

I can´t find anything in the documentation !

[Andre_Saller]

The SCC-RTD module has a built in 30 Hz filter, so it is of not much use sampling the signals with more than 15 Hz. But as you need 10 Hz, the SCC should be fine for you. If the SCC module would not have the filter, your callculation would be correct, by the way.

If this is to slow for you, I would recommend using a cDAQ chassis (cDAQ-9172) with RTD modules (NI 9217).

Hope this helps!

André

[hemmerling]

Thanks alot for mentioning the filter as limit.

So the 30 Hz Filter is similar to the 100 Hz of cDAQ ( so is the 100 Hz the filter )
or the 15 Hz is similar to the 100 Hz  ( so is the 100 Hz the maximum useful frequency ) ?

Well I just learned from the german sales department that the drivers for
cDAQ chassis (cDAQ-9172) which work with RTD modules (NI 9217).
are going to be published this year 2007 until 1.April ( during the 1st quarter of the year ),

so that *at this moment* cDAQ is no solution yet,
but its on our radar of course.

Sincerely
Rolf

Message Edited by hemmerling on 01-15-2007 03:44 AM

Message Edited by hemmerling on 01-15-2007 03:50 AM