DAQmxCfgBurstHandshakingTimingImportClock and 653x

[Larry X]

I'm porting Traditional NIDAQ code that uses a PCI-6533 to read and write from / to an external device, using burst mode handshaking  The external device supplies a clock that the 6533 uses when it is reading 16 bit words from the external device.  I tried using DAQmxCfgBurstHandshakingTimingImportClock to specify Dev2/PFI5 as the clock source (it just happens to be Dev2 in my case), since I was told by NI that this is the DAQmx terminal name for PCLK2 on the 6533.  However, when I start my read task, I get error -89136, "Specified route cannot be satisfied, because the hardware does not support it."  It suggests using PFI4, or RTSI0 - RTSI6 instead.  Well, I can't do that, since I need to use PCLK2 (unless the info I was given about PCLK2 == PFI5 is incorrect). 

Furthermore, in 653x.chm, the page "Generating and Receiving Digital Patterns and Waveforms - Sample Clock" says, "the [sample] clock signal can be received from the PFI <2..3> or PFI <6..7> pins on the I/O connector."  So using either PFI4 or PFI5 conflicts with that.

Can someone please tell me what I need to do to use PCLK2 (connected to an external device's clock) as my 6533 sample clock for reading from the external device?   Where is the mapping from PCLKs, ACKs, and REQs, to 6533 port and line numbers documented?  Thanks.

[Matt_A]

Hello Larry,

In Traditional NI-DAQ (Legacy) PCLK2 maps to pin 6 on the 68-pin connector; in NI-DAQmx, PFI5 maps to pin 6. So, when you were told that PCLK2 maps to PFI5 this was technically correct. For more information about the physical connections of your device you can view the documentation online. For Traditional NI-DAQ (Legacy) you can reference page C-1 in the NI 653X User Manual for Traditional NI-DAQ, and for NI-DAQmx you should refer to the section called "Signal Descriptions" in the NI 6533/6534 for NI-DAQmx™ Help, which you referenced earlier.

However, I believe the problem you are having is a result of the different implementation of burst handshaking in NI-DAQmx as compared to Traditional NI-DAQ (Legacy). In Traditional NI-DAQ (Legacy) the REQ, ACK and PCLK signals are used to transfer data. However, in NI-DAQmx the signals called Pause trigger, Ready for Transfer event and Sample clock are used to implement burst handshaking. You can find more details about implementing burst handshaking in NI-DAQmx in the NI 6533/6534 for NI-DAQmx™ Help. Specifically, I would recommend that you review the sections called "Using a Clock to Transfer Data Between Two Devices-Burst" and "Considerations for Using the Burst Handshake Sample Timing Type".

In addition, there is an example called that "DOsingleBufBurstHandshakeExtPClock653x.C" that you may find helpful. This example is installed by default at the following path: C:\Program Files\National Instruments\NI-DAQ\Examples\VisualC\Do. I hope this is information is helpful. Let me know if you have any questions or need any help finding the example.