PXI_Clk10 can't be found in PXI6115.

[Frogreenmm]

I have two PXI6115, and I want to synchronize them. I found a example from NI examples. It said the two PXI cards can be synchronized through sharing RefClk10. But I can't found this reference clock signal. Can you give me some suggestion? Thank you so much.

[SKowl]

Different families of PXI devices use different kinds of synchronization. 'Master-slave synchronization' ( where a master device provides the timebase and start trigger)  is used for S-series devices ( e.g. PXI 6115). Chapter 11 in the  S-series user manual describes this in some detail. Another kind of synchronization is 'Reference clock synchronization', where devices draw their timebase from a signal on the backplane, and the start trigger from a master device. The RefClk10 you mention is actually the PXI_Clk10 -- a 10MHz signal on the PXI chassis backplane.

You could try this example that comes with DAQmx-- Multi-Device Synch-Analog Input-Finite Acq-Analog Start.vi. 

Hope this helps.

[Frogreenmm]

I'm sorry that my boards are PCI6115. I had tried the example "DAQmx-- Multi-Device Synch-Analog Input-Finite Acq-Analog Start", butI failed. I also connected the two boards by RTSI cable for hardware and "connect terminal" for software. It still didn't work. I connected master/ai/sampleclock to master/RTSI0, connectd salve/RTSI0 to salve/ai/sampleclock. I also got master/ai starttrigger terminal, and connected it to salve digital start trigger. The error information is 89137. How can I solve it? You are appreciated.

[SKowl]

Yes, you do have to connect PCI devices with an RTSI cable to synchronize them. 

The error 89137 means that the "Specified route cannot be satisfied, because it requires resources that are currently in use by another route.". You are getting the error mostly because your connections are such that there are multiple sources driving a single line, and hence the conflict.

In the  DAQmx-- Multi-Device Synch-Analog Input-Finite Acq-Analog Start.vi, select option 1 i.e. M series sharing reference clock for PCI devices. PCI S-series devices also use the same mechanism for synchronization. In the VI just connecting the refclk from the master device to the slave device translates to a lot of routing under the hood. 

Explicitly connecting the RTSI0 to the respective sample clks will not help. It is the sample clock timebase ( the signal from which the sample clock is derived) they need to share. Moreover, I'm not sure though, if you are explicitly connecting terminals, there may be other parts of the route that also need to be established for sharing the timebases. 

Let me know how it goes. 

[Frogreenmm]

I have tried. It failed. The error information is 200452. I don't know why. Acturally, my boards work well in traditional DAQ. In that case, I did as my last mentioned physical connection the terminals for share of clock and start trigger.

[SKowl]

If you could post a screenshot of what you're doing, that might help troubleshoot it better.

The 200452 error is because a certain property you're trying to use is not supported on the PCI-6115.

[Frogreenmm]

I made a screencopy, but I don't know how to paste here.

My boards are PCI6115, but I can't find RefClk10.

Message Edited by Frogreenmm on 02-05-2009 01:46 PM

[SKowl]

You could add the screenshot as an attachment.

The 10MHz reference clock is available with M-series devices (62xx) and not S-series devices(61xx), so the question of using it to synchronize S-series devices does not arise.

If you are explicitly connecting terminals in the VI, it appears the timebase should be routed to/from the RTSI7 line only. Any remaining available RTSI lines [0...6] can be used for sharing the start trigger.

[Mcdan · Accepted solution]

Frogreenmm,

Let me see if I can help clear up some of your confusion.  First of all, PXI_Clk10 is a signal that is present only in PXI chassis.  PXI-6115's have a PLL which can lock to this signal.  However, as you've mentioned you have a PCI-6115 so this synchronization scheme is not available to you.  To synchronize these devices, you must share signals between the devices across some interface.  You've mentioned that you have a RTSI cable, so that will be the easiest way to do so.  To use RTSI with DAQmx, you'll need to go to Measurement and Automation Explorer (MAX) and add the RTSI cable as a DAQmx device.  This lets DAQmx know about the presence of the RTSI cable, and will also allow the driver to automatically make routes between your devices using this interface.  To add the RTSI cable, go to MAX and expand the Devices and Interface control.  Right-click on NI-DAQmx Devices and choose Create New DAQmx Device->RTSI Cable.  The RTSI cable should then show up in your list of devices.  Right click on it, and select "Add Device to RTSI Cable."  Do this to add both of your PCI-6115s to the RTSI cable.

At this point, I'm assuming you have physically connected the two devices with the cable and now DAQmx knows about this connection.  Now, we could use one of several methods to synchronize the devices.  We can share a master timebase and start trigger between the two devices, or we could share a sample clock and a start trigger between the two devices.  The DAQmx shipping example titled "Multi-Device Synch-Analog Input-Finite Acquisition.vi" is an example of how to share a timebase and start trigger (Look at the block diagram case "E & S Series Sharing Master Timebase").  In this case both devices will share the timebase from Dev1, and both devices will use Dev1's start trigger to begin their acquisition.  As long as you've added your RTSI cable to MAX, and added your devices to the RTSI cable, DAQmx can take care of the details of routing these signals.  One important note about this approach is that you must call start on the "slave" (Dev2) 6115 before calling start on the "master" (Dev1).  This is so that Dev2 is ready for the start trigger signal when Dev1 sends it.

You can use a very similar approach by sharing a sample clock between the two devices rather than sharing the master timebase.  Again, I'd advise that you also share a start trigger, and start the "slave" device before starting the "master" device.

Hope this helps,
Dan

[Frogreenmm]

Thank you so much. I understand now.

Another question is that it can't find the start trigger now.^_^ just use the example that you mentioned. the information is :

Possible reason(s):

Measurements: An attempt has been made to use an invalid analog trigger source.

Ensure that the trigger source you specify matches the name of the virtual channel in the task or matches the name of a non-scannable terminal that the device can use as an analog trigger source.

Property: Start.AnlgEdge.Src
Corresponding Value: APFI0

Valid Choices: Dev1/ai0, PFI0

Task Name: _unnamedTask<2>

Thank you very much for your patient explain.