NI 6008 to control I/O Solid State Relay Omega DCO5-C

[kmartin9231]

Hi NI Community,

I am trying to use my NI 6008 to send a TTL signal for switching 12V DC in a solid state relay (Omega DCO5-C).  This relay is controlling the power to a solenoid valve. 

For the solid state relay, "output modules receive TTL signals from the computer interface, and will switch ac or dc power lines on or off".   The LED light on the backplane light up when 5V is supplied, but I do not get switching of the 12V DC power.  

Can I not send the appropriate TTL signal with my NI 6008?   Is there any way to create the correct signal?  I have read up on TTL signals, but this has been my only lesson.

Any advice is appreciated. 

Thank you in advance,

Kelly

[crossrulz]

Looking at the spec sheets, the typical input current for the relay is 10mA.  But the 6008 can only drive 8.5mA.  So you probably need to add in a digital buffer circuit that can allow a higher current, at least the 27mA that is spec'd in the relay as the max input current.

You will have this problem with almost all digital IO.

[kmartin9231]

Thank you for your quick reply.  You are correct: I measured the voltage across the relay, and I only have 2.45 V.  I'm not expereinced, so the task of implementing a digital buffer circuit sounds daunting.  Could I connect two digital outputs in parallel to the relay, switching them on at the same time?  Or, does anyone have any recommendations of a relay that will switch 12V DC, 1.2 A with the NI 6008?

Thanks again for your time.  Happy Halloween.

[crossrulz]

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@kmartin9231 wrote:

I'm not expereinced, so the task of implementing a digital buffer circuit sounds daunting.

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Not  at all.  You just need to know how to connect up an IC.  A quick look on Digikey: http://www.digikey.com/product-search/en/integrated-circuits-ics/logic-buffers-drivers-receivers-tra...

You could likely just get around the issue with this one: SN74ABT245BN

[kmartin9231]

Thanks!  I will give this a try.