11-05-2012 01:46 AM
I have a problem with labview .. Actually I want to control a 12V electromechanical relay through digital output module to connect or disconnect the path .. The aim here is to control the connectivity of the load or component path (on/off) using relay and NI 9474 ..
My question is how to build that in labview ..
if there is any example or tutorial that may help . Please post it for me
Thanks a lot ,
11-05-2012 06:09 AM
Welcome to the forums.
What troubleshooting steps have you taken?
Are you able to control the relay through MAX (Measurement and Automation Explorer)? You should be able to manually switch the digital lines high and low from MAX to test its functionality.
Writing data to the digital output lines will be done using DAQmx. The best place to find an example will be using the inbuilt example finder which LabVIEW provides.
Help >> Find Examples >> 'Hardware Input and Output' >> DAQmx >> 'Digital Output' and look through the examples there.
The 9474 is a sourcing Digital Output module therefore it has to be supplied with a source to output (i.e.. 12V in this instance). Please refer to the manual here to ensure that you have it properly connected and do not risk damaging the module by operating it outside of its specification.
11-05-2012 07:30 AM
Thanks for relpying but I got confused I am not a Pro in labview.. from what I know .. I will connect the digital output module to relay .so
the path is on when digital output module sends a pulse to relay to connect and
the path is off when there is no signal to send ..
Isn't that correct ?
My question is I don't know how to build that in labview .. Iam looking for an example of vi that uses relay and digital output module to connect and disconnect the path ..
sorry I know I'm demanding alot .. I searched about it and I got nothing helpful
but really thanks for your reply ..
(^__^)o0O [ you Made ma Day ]
11-05-2012 07:33 AM
Just search for the digital output examples as already stated. When you turn the digital output on, it will output 5V in the line you told it. This 5V will then either energize or deenergize your relay (depends on the exact circuit).
11-05-2012 08:17 AM
remember....DO is a ttl signal and not a source. you will have to buffer it or use some kind of driver(transistor,mosfet,optocoupler,ssr,ect....),
11-05-2012 09:29 AM
Ahaaa .. Okey ..Got your point .. Thanks for that.. ^__^
but still my question is unanswered ..
wanna know more about >>> guess what >>>>VI of digital output module and relay to connect and disconnect the path of load
I looked for examples but I didn't find what I need
THANKS a lot .. I really appreciate your help ^__^
11-05-2012 09:45 AM - edited 11-05-2012 09:45 AM
I think you get confused with some stuff in your system....
So essentially, the VI only tells the 9474 to open or close the relay. Depending on the external power/relay connection, this could result in "negative logic". So "open the relay" might result in "ON".
So i wonder what you are asking for.
a) a VI using DAQmx API to control the 9474. Refer to Chris suggestions here.
b) connecting a power source and the relay to the 9474 (external connections). Refer to the manual as RavensFan posted.
hope this helps,
11-05-2012 09:47 AM - edited 11-05-2012 09:53 AM
Look at Hicks examples again. There are lots of DAQmx examples including ones on digital outputs. If anything, there are too many examples. All you need is a DAQmx Write set for digital output, 1 channel 1 sample. Boolean
For a relay, you just need to match an external power source with a relay, and pick a relay that doesn't draw too much current in its coil that would exceed the 1 A rating of the digital output channel.