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Software handshaking in USB-6009

Hello!
I need help!
 
I use USB-6009 with my device. The USB-6009 out 8 bit parallel data to device 3 time per second. How a can do software handshaking, in order to USB-6009  tell to my device, thats byte is true on USB-6009  port ? Or how my device know, that data value has been write out at USB-6009 port ?
 
Thank you!

Message Edited by Mihalis on 02-27-2006 01:05 PM

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Mihalis,

With what are you interfacing? Does it support any asynchronous protocols? You should be able to use an additional line on your 6009 as a "data ready" signal. This line would go high after you have written data to your 8 DO lines, and low before they are changed again. At this point, your device should latch the data, on either the rising or falling edge. Are you able to implement this functionality on your device? You may also need some input signal to the 6009 which your device asserts when it has read the value on the bus. The 6009 would hold "data ready" high during this time. Alternatively, your device may have a "hold" line which indicates whether or not it is ready to accept data. The 6009 should always check the state of this line before deasserting the "data ready" line and moving on to the next port value. Even with software-timed updates, you will have no problem implementing this protocol for a 3Hz rate. Please let us know if you have any more questions.

Hope this helps,
Ryan Verret
Product Marketing Engineer
Signal Generators
National Instruments
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Hello Voltage V... !
My USB-6009 interfacing whith microcontrollers system,  therefore it support any asynchronous protocols. I programming microcontroller myself.
I know, that I must use an additional line on 6009 as a "data ready" signal, bat I do not know, how it make by LabVIEW. I used VI like "write dig port.vi" for didgital data out. How i can modify this LabVIEW VI for software handshaking ? Can you give me example ?
 
Regards,
Mihalis.
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Mihalis,

You simply need to use your other port to assert a line before, and clear a line after you write your data. Attached is a modified version of your example, which accomplishes this. The order of events is enforced by the wiring of the error cluster. Please let me know if you have any questions.

Hope this helps,
Ryan Verret
Product Marketing Engineer
Signal Generators
National Instruments
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Ryan, thank you for example! This helps me very much! This is, that I want.
 
Best regards, Mihalis!
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