USB 6009 Digitial I/O Startup TTL High or Low?

[Dennis_Knutson]

You are speaking nonsense. It is totally irrelevant to this thread whether or not you can control some piece of equipment with a program. I don't understand why you fail to see the point of this. Power up states is completely different than programatic control. Power up states is expressly about control before a program can be run.

[apok]

enough said...you win "the mega posts award"!

[SnowMule]

: popcorn :

[apok]

Assuming that a “HI” on the relay (SSR) inputs puts your equipment in an “active” state, I suggest putting an Inverting Voltage Comparator on that input. Nothing connected to the input of Comparator with always default to a LO state. You need an active LO to the comparator to output a HI to the SSR. Since the digital output of the 6009 is an Open Collector with an internal pull up resistor, the OFF transistor state will output the 5 volt pull up. So program your test VI to have active LO’s instead of active HI’s. Hope this solves your dilemma with the 6009.

“Offer solutions…not more problems”!

[apok]

now if the relays were coiled...you will need a ULN open collector driver. the ic needs an active high to activate and again, you want an active lo. so like my previos post, put an inverting voltage comparator to the ULN. the circuit flow should be....DAQ DO>>INVERTING COMPARATOR>>ULN>>COILED RELAY...

[sahani]

Hi 

Yes I need  a HIGH to drive the Relay, so I will try what you have mentioned to use a voltage comparator and ULN,  I will Let u know the result what I have achieved. 

Thanks for the advice. 

Regards

Veer

[apok]

depending on what kind of relay it is...DAQ DO>> INVERTING COMPARATOR>> SSR or DAQ DO>> INVERTING COMPARATOR>>ULN>>COILED RELAY, all together with your "active lo's" digital outputs.

[sahani]

Hi

If i use ...DAQ DO>> INVERTING COMPARATOR>> SSR  it inverts the line during the start up and gives a logic Low, but when I run the Labview code it gives me a Logic  High at the output because the USB 6009 switches to logic Low once the Labview code is running and waiting for trigger.

so, I dont think this will solve my problem, because I am using this application to fire a trigger box and in either of the case even before it takes the input , it tiggers.

Thanks

Veer 

[johnsold]

Veer,

In cases like that you may need to put a latch in your external circuit.  Set up a positive edge triggered flip flop (type D). Use a hardware power up reset circuit to make sure it starts in the off state. When the 6009 starts running write a Low to High transition to the clock line of the flip flop while holding the D input High.  This will set the output On and turn on the SSR. High to Low transitions due to enabling the DO lines will not trigger it.

Lynn

[sahani]

Hi Lynn,

By my understanding Should I connect my digital logic output signal from the USB 6009 to the Clock Pin of the D type Flip flop and  use a external switch on the input of D of flip flop to change the states or just connect as a feedback from NOT Q to D, so it is always opposite of Q.

will this connection will work form my application and will give a logic low until it does not change the states from 0-->1 in the clock input.

Thanks

Veer