Digital Relays to DAQ

[siks1]

I have finally shortlisted my choice of buffers to below 3 : 

http://www.digikey.com/product-detail/en/MM74C244N/MM74C244N-ND/10379

http://www.digikey.com/product-detail/en/NJM4556AD/NJM4556AD-ND/673767

http://media.digikey.com/pdf/Data%20Sheets/Texas%20Instruments%20PDFs/ULN2003V12.pdf 

I have tried for UL200x in Texas Instruments, but I didn't find the buffer with that part no. May be, I think you just gave me the series and asked me to figure out the remaining part no based on my requirement. I have searched for ULN Buffer in digikey website and found this part no : ULN2003V12 (I have attached the datasheet). 

Can you advise me about which one I have to pick from the above?  

Thanks

MSC

[Dennis_Knutson]

Sorry, I mistyped the generic part and missed the N.

[siks1]

Yeah, it's fine. However I was able to understand you meant ULN. 

As I said in my previous message, I selected the part No : ULN2003V12DR

It has a current output of 140 mA and Voltage Load : 16 V (max). 

Data Sheet attached with this message. And also posted the link below : 

 http://www.digikey.com/product-detail/en/ULN2003V12DR/296-30538-1-ND/3455515

My other choices would be the two models mentioned in my above message as well as below this link : 

http://www.digikey.com/product-detail/en/SN74ABT541BPWR/296-4028-1-ND/375158

http://www.digikey.com/product-search/en?x=0&y=0&lang=en&site=us&keywords=BUF602

Please let me know which one works for me. I just want to make sure I buy the correct parts!!

Thanks

[siks1]

I have decided to buy ULN2003A after reading through the datasheet and with the knowledge I acquired reading through some articles posted about the buffers here and there. I have attahced the datahseet of the ULN2003A with this message. I think it works with the voltage 5V and the current output is higher than 60mA. I am planning to buy three of these buffers and three of the relays. So do you think I am on the right track? I know I still have to do figure out the circuit and then the Labview Code. But I am determined to make this work!

Can anybody advice me where to start with regarding the circuit design and then coding with the labview. I am very new to this because I am majoring in Mech Eng and still freshman. I have worked on some coding with labview like case structures, boolen operations, LED lighting up and then For Loops as well as While Loops. I haven't got to state machines yet!

Also can someone help me regarding the wiring of these buffers to scb-68 blocks. How do I determine the pins to which I have to wire them and is there any configuration that I have to set my DAQ for this specific purpose to work on this application?

The link of the buffer I selected : http://www.digikey.com/product-detail/en/ULN2003A/497-2344-5-ND/599603

Thanks

MSC

[Dennis_Knutson · Accepted solution]

The ic has 7 separate buffers in it so you only need 1 ox for the 3 relays.

The pinout of the scb-68 it's the same as the DAQ device. You look in the manual for the pin numbers of digital outputs 0, 1, and 2. These are what you wire to the first 3 inputs of the ic (pins 1, 2, 3). You write the corresponding outputs to the relays.

You should open Help> Find Examples and look under Hardware Input and Output>DAQmx for digital output. It's pretty basic. A digital output task can be set with a Boolean - either true or false. Multiple channels (Dev1\do0:2) use a Boolean array.

[siks1]

Many thanks for your response. 

I have understood the "labview code" you meant (Boolean Array for Multiple Relays) and that makes sense to me. I should be able to do this. 

And also I have understood the wiring sequence after reading your message. If I run into any problem related to hardware when I actually do this, I will message you.

Edit : I am purchasing the relays that are "Normally closed". Is that going to make any difference or I should go for "Normally Opened"??

[Dennis_Knutson]

Depends on what you want the startup state to be.

[INOC]

Dennis is right. It all depends on how you want the start up, and how much activity you would require. 

[siks1]

Hi,

While I am referring to the manual, I read that the pins can be either configured to be Digital Input or Digital Output. 

And also please check this image. Are the pins with names P0.0, P0.1, P0.2 are what you are referring to as the channels which I should connect my Digital buffer's IC?? And also are there any steps that I need to take to configure them to be as Digital Outputs?  And I have looked in the examples (Hardware Input and Output-DAQmx-Digital Output. There are 4 examples in it and which one would you think would be the specific one that I should look into. I have looked into Dital -SW-Timed Output.vi because it says it demonstrated how to generate digital output data using software timing. But I am not sure if this is the one that can help me. And also, in the requirements for this example , the DAQ board which I am using (i.e, PCIe-6321 is not listed).

pls help.

Thanks

[Dennis_Knutson]

You need to look at the pinout of the 6321. You do not have an M series board.

The example for software timed output should work. The channels get defined as outputs with the DAQmx Configure Channel function.