How2get Digital IO data in RT from an (D)Thermometer

[vorli]

Thermometer (SMT 160-30) on DIO (50pin MIO Device)

How to get boolean / and time in an wave form

[Carl L.]

Worli,
Looking at the specifications for the SMT 160-30 it does not seem like you are interested in the boolean value. The output is a square wave with the temperature represented by the duty cycle.
http://www.smartec.nl/pdf/DSSMT16030.PDF

To measure duty cycle you will want to use a counter. There are examples for measuring semi-period (measuring the length of both the high and low portion of the square wave). Or even better this example already measures the duty cycle:
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3E0B356A4E034080020E74861&p_node=DZ52329&p_source=External

Carl L
National Instruments

[vorli]

thats right but i'm working with an PCI-6024E card
(with a so called black box)
this card has 2 counters (i already managed to get the temp using this counter (but i need 2 for each sensor (couse i need uptime and downtime of the square wave)for calc)

i need to plug at least 5 therm-sensors(smt 160-30)
so i want to get the data by Digital Input / measuring the time i tried a few times but the results are too bad (extremly shifting values)

maybe now its clearer

[Carl L.]

Vorli,
I do not think that you will have much luck reading the signal with the digital I/O on a e-series board. The frequency of the square wave is 1-4 kHz, so you would have to be able to sample at atleast 100 kHz to get any kind of accuracy. To do that you would need strobed i/o. For example the PCI-6533 or PCI-6534 could do that.

To get good readings you would need to use a counter. If you look at the example program that I linked, you will notice that it only uses one counter. So you would be able to read 2 sensors per e-series board. Or you could buy a counter board. The PCI-6602 has 8 counters.

Carl L
National Instruments

[vorli]

thx much for help

Christoph Vorlicek