Hardware timed digital output (NI PCIe-6351 + BNC-2111)

[huwcy]

Hi,

I am trying to output two digital pulse trains to act as a TTL signal controlling two lasers. 

To do this, I first generate a hardware counter on Dev1/ctr0 at a user defined frequency. This counter then serves as the source (Dev1/Ctr0InternalOutput) for the Digital Output on Dev1/port0/0:7 which uses a user defined 1-D waveform input.

The desired output would be:

Dev1/port0/0 --> on off on off on off ...      at the desired ctr0 frequency

Dev1/port0/1 --> off on off on off on ...

However on my current setup (NI PCIe-6351 + BNC-2111) I don't have direct access to port0 thus I tried outputting the digital signal on Dev1/port1. This gives me an error 201062, indicating port0 does not support hardware timed digital output. (http://forums.ni.com/t5/Multifunction-DAQ/Error-201062-when-performing-continuous-reading-of-a-Digit...)

My question is: How would I gain access to the port0 and connect to a BNC connector, via extra hardware or otherwise?

and if this is not possible,

How would I recreate the above using either an analogue output or using more than one counter (Ctr) outputs?

Sorry for the length of the message.

Any help would be much appreciated.

[LanxiZ]

Hi huwcy,

My name is Lanxi and I am an Application Engineer from NIUK. I will be assisting you with your query.

Here are some suggestions I have on this issue:

1. Instead of using a BNC connector board, a connector block may help with your problem. NI SCB-68A gives you access to all 8 pins of port 0 of your PCIe card.  The link below is the User Manual and Specifications of the NI SCB-68A:

“NI SCB-68A User Manual and Specifications”:

http://digital.ni.com/manuals.nsf/websearch/5E95C9F064A27E1386257A60006E80EE

If you want to access your output signals through the BNC terminals, you will need some “BNC to two wires” cables. This kind of cable can be easily found through Google.

I did some research on how to get access to port0 through BNC-2111 but unfortunately I did not find any method enabling you to do that.

2. You are right in saying that pulse train can be generated using analogue output and the link below shows you how to do that:

“NI-DAQmx: Creating a Custom Pulse Train Using Analog Output”

http://zone.ni.com/devzone/cda/epd/p/id/1621

I hope this helps please let me know how you get on.

Kind Regards,

Lanxi