i am using pci-6221 i need to interface it with thermocouple with voltage upto 5v

[ASRA]

i am using pci-6221 as my daq card and labview version 8.2.this card is giving the constant signal input of 10.5 volts to input analog channel AO on pin 68 and 34.why it is showing 10.5 even i havent connect any input.i am using k type thermocouple and after signal conditioning with tl0804 i need to interface it with AI channel 0.i dont know about the output drive current at any of the output pins of this card.i need to actuate an electric rod which needs 24 volts DC.i give the input to AI pins with variable dc power supply after reaching the limit i set(eg:2v) it instantly jumps to 10.5 volts.

[RavensFan · Accepted solution]

Do you have your DAQ task set up for differential or single-ended mode of acquisition for the analog input?

I don't understand your comment about connecting the AI pins with a DC power supply.  Why are you connecting a DC power supply to the analog input?

Are you using an analog output or a digital output to actuate the electric rod?  I'm going to assume you are looking for on/off control.  A digital output doesn't have the voltage or the current to drive something that big.  You may be able to find a relay rated for a 5VDC coil.  Check the current requirements.  With that you can have the relay connect or disconnect a 24 VDC power supply going to the actuator.  Make sure you have a protection diode wired across the coil of the relay so that the magnetic field of the coil doesn't damage the analog output of your card.

Another possibility is to have the 5 VDC output drive a transistor circuit that switches the 24 VDC circuit.

[ASRA]

thanks for the reply.its mark differential.not siingle ended mode.is there any difference between the two.i am new to this software.how can i calibrate the signal.and what is the purpose of the green test button on the tab when we click on  DAQ assistant block.forexample if my voltage crosses certain limit i like to actuate the electric rod by using 5v drive relay or transister switching 24 dc.i used greater than comparator block from comparison pallete but it give constant 1(high) and turn on an on software.but how can i get signal at the a0 analog channel(pin 22 and 54gnd).how can i use the comparator output to actuate the rod.i have dropded on block diagram another daq assistant block(daq2) and connect it to simulate signal from express pallete.

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Message Edited by ASRA on 01-29-2010 11:06 AM

[RavensFan]

Single ended means the signal that goes into an input (such as AI0) is referenced to ground.  Differential means both leads are wired into analog inputs (such as AI0 and AI8, but may also be listed as AI0+ AI0-), and are measured relative to each other.

I am unable to understand the rest of your message.  If you can rewrite it where you actually capitalize the first letter of the sentence and put some spacer after the period, it may be more readable.  Right now it is like a long run on sentence.

[ASRA]

Thanks for the reply.Its mark differential.not single ended mode.How can i calibrate the signal.It asks about the reference values(atleast two values in rows), while doing calobration. What is the purpose of the test button on the tab when we click on  DAQ assistant block. Forexample if my voltage crosses certain limit i like to actuate the electric rod by using 5v drive relay or transister switching 24 dc etc.i used greater than comparator block from comparison pallete  it give constant 1(high) which is right and turn on an LED on software. But how can i get signal at the a0 analog channel(pin 22 and 54). How can use the comparator output to actuate the rod. I have dropded on block diagram another daq assistant block and connect it to simulate signal from express pallete. I am doing right by using this second DAQ block or i should just add a channel to the first DAQ assistant. Tel me since my input is analog i can get the DC output at DIO channel. I need to know how can i use the DAQ assistant in my application..

[ASRA]

hello,

         I need to know exactly that how can i configure the analog input and DIO channels and get data in labview software by using these channels. I am comparing the analog input value from AI0 by using a comparator how can i  I am using an M series PCI-6221. and labview version 8.1...also I need to actuate the 24V DC contractor which will actuate the electric rod.

[ASRA]

hello,

Thanks for the reply.Its mark differential.not single ended mode.How can i calibrate the signal.It asks about the reference values(atleast two values in rows), while doing calobration. What is the purpose of the test button on the tab when we click on  DAQ assistant block. Forexample if my voltage crosses certain limit i like to actuate the electric rod by using 5v drive relay or transister switching 24 dc etc.i used greater than comparator block from comparison pallete  it give constant 1(high) which is right and turn on an LED on software. But how can i get signal at the a0 analog channel(pin 22 and 54). How can use the comparator output to actuate the rod. I have dropded on block diagram another daq assistant block and connect it to simulate signal from express pallete. I am doing right by using this second DAQ block or i should just add a channel to the first DAQ assistant. Tel me since my input is analog i can get the DC output at DIO channel. I need to know how can i use the DAQ assistant in my application..

I need to know exactly that how can i configure the analog input and DIO channels and get data in labview software by using these channels. I am comparing the analog input value from AI0 by using a comparator how can i  I am using an M series PCI-6221. and labview version 8.1...also I need to actuate the 24V DC contractor which will actuate the electric rod.

[RavensFan]

I think you need to started reading through the resources located here.

[ASRA]

OK.thanks. U r right i should first go through these tutorials.