Choosing the gate signal for buffered position measurement

[bigburnsgeoff]

Developing a buffered position measurement tool in LabVIEW which reads the position of two quadrature encoders at finite time intervals on a continuous basis. Having used the buffered position examples as a basis with the counters source as the gate signal. I now want to use an accurate clock to provide a high speed gate signal so that the position of the quadrature encoders is read continuously at a much faster rate. I am using a PXi-6602 so I thought that I would wire the 100kHz clock to one of the RTSI channels and then use this as the gate signal. I have found this impossible to do and cannot find any examples. So how can I use a high speed clock as the gate signal, and secondly is there any way of doing this
so that you can choose/control the frequency of the gate signal?

By the way I am using the advanced counter/timer vi's and does anyone know of a good piece of text that illustrates counter timer applications in LabVIEW?

[Filipe A.]

Hello;

You can use another counter of your 6602 board to generate a accurate pulse train and use that as the gate for your other counters. I'm attaching a Labview VI which routes counter 1 output to counter 0 gate pin. You will need just to generates the pulse train on counter 1 and bundle the two VIs in a single one.
Hope this help.
Filipe

[bigburnsgeoff]

Filipe,
Cheers for the reply. I have used your suggestion and developed a buffered position measurement tool that utilises a pulse generator as the gate signal, so that I can call the data as fast or as slow as I require. It works well but it is suffering from being limited to what combination of counters that I can use. In the attached file one counter is used for the buffered position measurement while a second is used for the pulse generation. This works very well if Counter 0 is used for the position measurement and Counter 1 is used for the pulse generation. If a different combination of counters is used for the position measurement and pulse generation then it doesn’t work. I have thoroughly checked to make sure that the appropriate co
unters are wired and assigned properly, so what am I doing wrong? No matter what the counter combination is, the signal generator works but the counter assigned for the position measurement does not. For example if counter 0 is defined for the position measurement and counter 1 is defined for the pulse generation then it works fine. If any other counter is used for the pulse generation or the position measurement then the position is not recorded although the pulse generator part does work. So this suggests that something is not defined appropriately but I don’t know what it is. Have you any ideas?

Many thanks

[Kevin_Price]

RTSI can be your friend here. I often find it convenient to put signals on the RTSI bus, even when I'm only using a single DAQ board like the PCI-6602.
When you are configuring your pulse generator, add the vi called "Route Signal.vi" to the chain. (found in Data Acq. Palette --> Cal & Config sub-palette. Use online help to get details). Send the pulse generating counter's output to one of the RTSI lines. Then set the Gate Specification for your other counters to be the same RTSI line.

-Kevin P.