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

[nsaddock]

Greetings,

I've developed a test solution with a USB 6009 device.  I've come to notice on bootup the device switches all my digital I/O lines to TTL High.  This has become a potential hazard for this test solution since it is fixtured to some heavy equipment that is controlled by the 6009 through a series of relays.  If there is a power failure and the  operator then boots the control system back online, when the computer enables or reads the USB device it switches all of my control relays on through the device which has set all signals to TTL High, setting some equipment into motion.  Is there a switch or relay or code or control that I can implement that forces the operating system or NI drivers, such that when this card is recognized by the computer it defaults to TTL Low and stays until the user boots labview and runs the control program?

Thanks,
Nick

[Laura F.]

Hi Nick,

From the User Manual of the 6009:

Power-On States

At system startup and reset, the hardware sets all DIO lines to high-impedance inputs. The DAQ device does not drive the signal high or low. Each line has a weak pull-up resistor connected to it.

So unfortunately, you cannot programmatically set the power-up states of the digital lines.  If you need this functionality, I would recommend looking at something like the digital PCI-6503 or the multifunction M Series which both have programmatic power-up states.

If you cannot switch to different hardware at this stage, I would recommend implementing external circuitry that disconnects the USB-6009 from the equipment when a power cycle is occurring. 

Regards,

Laura

[nsaddock]

Laura,

Thanks for the info.

I had seen that note in the manual, but was hoping there was some method (either a circut to pulldown the TTL or a driver specification).  I will implement external circuitry in the form of physical switches to ensure this does not occur.  Thank you again.

Best,
Nick

[sahani]

Hi Nick,

I am also using a USB 6009 Hardware module and I also want the digital lines set to TTL low at the start up and until the operator control the labview code.

May be you can help me,how did you have controlled the digital line to low state.

Thanks

Veer

[SnowMule]

6-year-old thread bump!

LauraF covered it.  The power-up state of the 600x cannot be programmed.  If a hazardous situation arises from the lines being pulled high, manage them with external logic.

[apok]

before your VI loop starts...initialize the DAQ outputs first(outside your loop). As the loop starts, initialize your equipment, run and then shutdown equipment and assign proper digital outputs as you did before.

[Dennis_Knutson]

The whole point of this thread is the lack of setting the power up states of the 6009 and what can happen before a program can start. Your answer does not address that at all.

[apok]

understood...........but was offering a different solution around equipment initialization, not a redesign of the 6009

[Dennis_Knutson]

But it is not a solution at all. Obviously, you can set the state of the digital I/O to whatever you want with a program running. That also obviously does no good when you are powering up the pc.

[apok]

reaallyyyyy......I use it control a Hipot equipment remotely....and ahhh, NO PROBLEMS HERE? regardless of the DAQ startup configuration.