Re: multi-channel analog i/p

[Stefen Paul <stefen4114@gmail.com>]

Hi,

Is there a comprehensive document/website available telling about including 'driver support' in EPICS  ?

How can one call vxWorks device driver routines from EPICS records and make the data read by driver routine available to the EPICS records ?

Like in my case where I have a vxWorks driver for VME based 32-channel analog i/p board. I need to read the h/w through the driver only because of some FIFO design issues. But once the data is read by the driver, I would like to pass each channel's raw data to an individual ai record.

Thanks,
Stefen.

On Tue, Jun 23, 2015 at 6:19 PM, Hartman, Steven M. <hartmansm@ornl.gov> wrote:

> On Jun 23, 2015, at 1:36 AM, Stephen Paul <stefen4114@gmail.com> wrote:
>
> Instead , I first want a record and its device support to read all the channels from the board in one go and then pass these values to individual 32 ai records for conversion.
>
> Can anyone suggest what type of record I can use before ai record to achieve this ?

Rather then a record for reading all of the hardware values, your device driver can have a worker thread responsible for reading from the hardware. This can be scheduled either periodically or based on some trigger. Your ai records would then read from the cached values from this worker thread rather then directly from the hardware. There are a number of drivers which take this approach, typically with more complicated hardware with a large number of registers to be read, or having a variety of different data types to support.

--
Steven Hartman
hartmansm@ornl.gov