Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Wed, 4 Jan 2017 11:59:17 -0600

On 01/04/2017 09:29 AM, Dirk Zimoch wrote:
> BTW, I have written an addScan command line function that allows to add
> scan rates in the startup script (rather than modifying menuScan.dbd)
> and which tries to crank up the vxWorks clock rate to at least 4 time
> the scan rate and warns if that is not possible.

The disadvantage with this approach is that database configuration tools
like VisualDCT will not know of the existence of any such new scan rates
so won't present them to the database designer as possible choices for
SCAN field values. This isn't a problem for an expert who doesn't use
VDCT, but it could be confusing for a beginner or someone who doesn't
know about the addScan command.

Note that from Base-3.15 onwards a menuScan choice string can specify a
scan rate in Seconds, Minutes, Hours or even Hertz/Hz, which would
confuse the current addScan() code when matching existing choices.
However the choice strings "10 Hz" and ".1 second" will generate two
different scan threads, and there is no internationalization available
for those unit strings. A more flexible scan mechanism is something I
would like to be able to add, but it might never actually happen.

- Andrew

-- 
Arguing for surveillance because you have nothing to hide is no
different than making the claim, "I don't care about freedom of
speech because I have nothing to say." -- Edward Snowdon

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System