MATLAB: How to synchronize the analog output on a Measurement Computing device with the Data Acquisition Toolbox 2.12 (R2008a)

Data Acquisition Toolboxmcsynctrigger

I have two MCC devices which I need to output fully synchronized data. I have connected the scan clock pin from one device to the other and I am using the external clock source for the slave device.

When I run the code, the devices are not synchronized.

Best Answer

The ability to fully synchronize the analog outputs on a couple of Measurement Computing devices is not avalable with the Data Acquisition Toolbox 2.12.

However, You can synchronize the output scan clocks. To do that, you need to use InstaCal to set the scan clock pin to output on the master device and input on the slave device.

Most MCC devices do not support hardware triggering for analog output, so to synchronize the two devices, you have to first start and trigger the slave device and then start the master. The slave will wait for the master to start outputting the scan clock signal.

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MATLAB: How to synchronize the PWM signals on a c2833xx DSP

ePWM modules use different timers, therefore you can see a phase delay between modules. However, the ePWM blocks have synchronization capabilities, as there is a synchronization signal that goes along each PWM block.

Each ePWM block has "sync in" and "sync out" settings. ePWM1 can receive a "sync in" signal from an external pin. Its "sync out" signal can be connected to the ePWM2 "sync in", and likewise, ePWM2's "sync out" signal is connected to the ePWM3 "sync in". By doing this, you can synchronize ePWM 1, 2, and 3.

Attached is a model that demonstrates synchronization. In this model, ePWM2 and ePWM3 are synced based on ePWM1. It was arbitrarily decided that ePWM1 would send a sync signal to ePWM2 every time the counter reaches 0. ePWM2 resets its counter to 0 when receiving the sync signal and passes the sync signal to ePWM3 that resets its counter to 0 as well. This method is very robust as there is a guarantee that the timers will not shift along the way since they are resynchronized at every period of ePWM1.

MATLAB: Can I use the National Instrument PCI 6521 with the Data Acquisition Toolbox 2.12 (R2008a)

This enhancement has been incorporated in Release 2009a (R2009a). For previous product releases, read below for any possible workarounds:

The PCI-6521 and PXI-6521 are not supported by the Data Acquisition Toolbox.

To work around this issue, you can add support for these devices by modifying the device configuration file.

To add support for Digital Input/Output subsystems using NI-DAQmx drivers, perform these steps:

1. Quit MATLAB.

2. Find the following file:

$MATLABROOT\toolbox\daq\daq\private\mwnidaqmx.ini

(where $MATLABROOT is the MATLAB root installation directory obtained by issuing:

matlabroot

at the MATLAB Command Prompt.)

3. Make a copy of this file and rename it to mwnidaqmx.ini.old.

4. Open the file mwnidaqmx.ini in a text editor, and add the following lines at the end of the file:

 [PCI-6521]
 hasAnalogInput   = false
 hasAnalogOutput  = false
 hasDigitalIO     = true
 digitalPortSize  = 8,8
 digitalPortCap   = 1,2
 [PXI-6521]
 hasAnalogInput   = false
 hasAnalogOutput  = false
 hasDigitalIO     = true
 digitalPortSize  = 8,8
 digitalPortCap   = 1,2

5. Save the file mwnidaqmx.ini and restart MATLAB.

Best Answer

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MATLAB: How to synchronize the PWM signals on a c2833xx DSP

MATLAB: Can I use the National Instrument PCI 6521 with the Data Acquisition Toolbox 2.12 (R2008a)

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