What DIO PCI card to use for actuator control with TTL?

[Albe_Ok]

Hello,

I have actuators driver which controls 5 actuators through 10 inputs (two inputs per actuator for open/close). Each line is pulled up to +5V internally. This allows the controller to be operated using open-drain (open collector) sources. The actuator moves when a corresponding input is drained. I need a DIO PCI card to control the driver with TTL pulses of ~2s duration. I was thinking about having all 10 digital outputs powered up to +5V when the card is configured for the output and then selectively write digital low to a channel I need to drain to activate the actuator, living the rest 9 channels at +5V load. Could you please advise me on what DIO PCI card I should use to do that? Any other alternative solutions to my problem?

Thank you in advance,

Al

Message Edited by Al B Ok on 11-15-2007 08:38 AM

[Matthew_W]

 Hi Al,

 Here is what I understand your application to be:

   Drive 10 digital outputs active-low, when active these outputs will sink current. The active state will be ~2 seconds long.

 This sounds like a good fit for NI-6509's or one of the Bank-Isolated boards like the NI 6510.

 The active time will be dictated by your control program, be it SignalExpress, LabVIEW, C etc. The cycle rate for this type of device will be
 at most 1Khz. This means you can't generate a square wave faster than 1Khz with these particular DIO boards. We do have high speed digital boards where the sample
rate is determined in hardware, these can acquire/generate up to 100Mhz.

 Please post back if you have questions about either of those devices.

Best regards,

 MatthewW
 Applications Engineer
 National Instruments

[Albe_Ok]

Hello Matthew,

Thanks for your instructions. It happens so that one of my collegues here has PCI-6503 DIO board. The difference between that board and 6509 that you suggested is the number of channels and the channel current. Since I do not need that many output channels is it OK to use 6503 instead?

I know that when the port is configured all the channels are reset to low state. My concern is whether the other 7 channels are reset when I set one channel to the active low output or they will stay in their high state (assuming I set them all to high after configuring the ports). I am planning to use LabView 8.5 to control the hardware.

The cycle time is not an issue since the actuators just open or close the shutters (2s is ~ time needed for the actuator to fully extend or retract - we do not have a feedback so we just time the active state of the actuator) and then they rest at their positions for minutes.

Regards,

Al

[Matthew_W]

 Hi Al,

 The NI 6503 should work for your application as long as it does not take more than 2.5mA to drive the actuator controller.

 In LabVIEW 8.5 you should start with the example Write Dig Port.VI. If you wanted valve 0 to be on, and valve 1- valve 7 off then you would just write 254 to the channel, this is 11111110 in binary.
 If you want all valves on then write 0 to the channel.

You will write to a individual line by writing a value to the entire channel.

Please do reply back if you need additional clarification on this issue.

 Best regards,

 MatthewW
Applications Engineer
National Instruments