Experimental Physics and
Industrial Control System

Hi Florian,

 

You would need to write an asyn port driver that is specific to USBTMC.  USBTMC is basically like GPIB over USB.  This driver will be similar to the VXI-11 driver, which is basically GPIB over Ethernet. 

 

That driver would implement the asynOctet interface, just like the drvAsynSerialPort driver does.  That should not be difficult.  You need to implement the ioctl for special operations. 

 

The following is from this document:

 

http://www.home.agilent.com/upload/cmc_upload/All/usbtmc.html?&cc=US&lc=eng

 

 

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ioctl(2): Special operations

 

As show in the above examples, ioctl(2) is used for special operations (everything that goes beyond text-based communication). The second parameter to ioctl(2) is a request code which indicates what kind of special operation you want the driver to perform. Valid request codes are defined in usbtmc.h. They are:

 

USBTMC_IOCTL_GET_CAPABILITIES

This request is used to get information about the device's capabilities. In this case, the third parameter to ioctl(2) is a pointer to a structure of type struct usbtmc_dev_capabilities (defined in usbtmc.h). This structure is filled by ioctl. See usbtmc.h and the USBTMC specification for details.

 

USBTMC_IOCTL_INDICATOR_PULSE

This request asks the device to light its activity indicator for identification purposes. This is an optional capability and may not be available with your device. Inspect the device's capability values when in doubt. In this case, the third parameter to ioctl(2) is not used.

 

USBTMC_IOCTL_CLEAR

This request is used to clear the device's input and output buffers. It is roughly equivalent to a GPIB device clear. In this case, the third parameter to ioctl(2) is not used.

 

USBTMC_IOCTL_ABORT_BULK_OUT

This requests aborts the last USBTMC BULK OUT operation, i.e. the last write operation to the device's command buffer. It is used to recover from I/O errors that occur during a write operation. Note that you can instruct the driver to do the abort automatically if an I/O error occurs. See Reference: Attributes for details. In this case, the third parameter to ioctl(2) is not used.

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Mark