Digital Relays to DAQ

[siks1]

Hi, 

I have quick question you. Can I connect multiple digitals relays to single scb-68 terminal block (DAQ is : PCI 6321)?

Through Labview, I want to turn on or off each of these relays.  Is it technically possible? becuase, I never connected more than one sensor to scb-68. 

The each of the relay acts as a binary switch to a brushed dc motor (motor voltage 3-12 v and rpm : 11.5 krm with weight < 80 grams). The dc motors will receive power from external dc power supply unit.  So the power for the relays (I am thinking) must be from DAQ. But I know DAQ can supply only very very less current. I am trying to source out if I can find relays that run with very current (which could be supplied by the DAq itself) Can you suggest me if this is possible? And also any information or source for the required digital relays would be lot helpful.

Thanks

MSC

[crossrulz]

You will need some digital buffers to increase your current capacity of your digital lines.  Just look on Digikey and you will find plenty.

[siks1]

Wow, thanks for your prompt response. So it is possible to have 3 digital relays connected to a single terminal block and operate them (turn ON / OFF)? 

What kind of digital relays would you suggest me?

[crossrulz]

You just need to connect to different channels.  Out of the 68 pins going to that connector block, I'm pretty sure there are at least 3 that are digital IO.  Check the specs on your DAQ board to make sure.

As far as relays, just go to Digikey and search for a solid state relay that meets whatever switching specs you might have.

[siks1]

Alright, after doing some research, I feel like this relays would work for me : http://www.digikey.com/short/72vpp2 

However, I am worried about the coil rating of the relay. I want to know how much of the voltage would the DAQ Board can supply to each of this relay? Would it be able to supply 4-5 V for each of these relay? If that is the case, then I can get rid of using digital buffers...but if I still require them, I will use them as well.

Thanks

MSC

[siks1]

I just realized the above link is not working. So I am attaching the data sheet that I have chosen.   

pART NO : G6B-2014P-US DC5

Thanks,

MSC

[crossrulz]

Coil rated for 40mA.  You will definately need some buffers.

[siks1]

Can you give me some idea like what specifications should I look for buffers? 

I did some research over websites, after you suggested me to use buffers for amplification of the current. And I found that, people are suggesting buffers, optocouplers..etc. It took me a while to source out the relays. But thank you for suggesting me to go for solid state relays depending on my requirement. It makes the job way easier and less expensive compared to digital relays.

Please give me some specifications to look for while sourcing out the buffer and also, in case of buffers, my DAQ's SCB-68 block will have a terminal linked to buffers and buffers will be linked to relays, right? 

Thanks, 

MSC

[crossrulz]

The main thing for the digital buffers it to get the current capability to drive your relays.  Many DIO cannot handle more than a few mA of output current.  There are buffers out there to be able to put out Amps of current.  So, based on what I see here, you will want a 5V buffer that can output at least 60mA for each signal.

[Dennis_Knutson]

As noted in several threads, the UL200x buffers are a pretty good choice.