pci-6221 MAX "digital out"

[Morten_Hvidberg_Knudsen]

Hi all

As a first step in trying out the 6221 for digital port output, I have tried to configure and test a task in MAX (v. 4.5.0f0) as follows:

Port 0

100 samples

1 kHz

AO sample clock

but not much happens and the task times out  when "run".

I noticed that compared to Analog Out this clock source this is termed "external", and I therefore suspect that some sort of "external routing " of a signal is required. But no "Connection diagram" (as the one present for analog input tasks) is available.

Any ideas ?

Furthermore:

What is the maximum sustained digital output rate (non regenerating)  to expect  from this card  (using Measurement Studio .NET DaqMX classes).

Regards

Morten

[Dan_K]

Hello Morten,

The problem is that in order to use the AO Sample Clock to clock a digital output task it is necessary for an analog output task to also be active. This cannot be done only in MAX.

There are a number of solutions to this problem.

• The first would be to write a piece of code that uses a analog output (dummy) task and a digital output task. Once you start the analog output task the clock will become active and usable by the digital output task.
• Upgrade to the PCIe-6321. This is part of the new X-Series MultifunctionDAQ devices. These devices are similar to their M-Series counterparts, being equal in price but with additional features. In this case a dedicated Digital Input and Digital Output clock that removes the need for dummy tasks or external clocks.

As far as the maximum rate you could expect to be able to generate your digital signal (non-regenerating), this is specified at 10 MHz, but this is dependent on how much of your PCI bus bandwidth you are using and the ability of your computer to write new data to the buffer.

This is another bonus of the X-Series devices. As express devices, bandwidth is not a problem, making this type of generation easier to implement.

[MHKDHI]

Thanks.

Three more questions though:

I have to inform the device, that is to receive the digital output, when a new data byte is ready on the 8 pins of port 0.

How do I, with the .NET DAQmx classes, route the AO clock signal to an output pin (according to the routing matrix for the device shown in MAX this is certainly possible) ?

What is the delay from the AO clock signal "ticks" until the new byte is available (and stable) on the output port ?

Or is there some sort of "new data ready" signal that can be routed to an output pin ?

Regards

Morten