Deadband and analog outputs questions

[Christopher Verges]

Hi OpenDNP3 gurus,

I'm looking into two different features of DNP3 and am need a bit of pointing towards the answer.  The questions:

1. Does the OpenDNP3 library support exception reporting of analog points by deadband? If so, how do you configure such a point?  (Group 34 objects?)

2. In dealing with Group 40 "analog outputs" object, are these objects both read and write capable?  (That is, if I write a value to a Group 40 object, can I query that same object to see the value that was just written?)

2(a). If the Group 40 objects are write-only (i.e. cannot be read), then is it typical to have a "shadow copy" available as an analog input under a different Group number?

2(b). If the Group 40 objects are read/write capable, do you have any insights into why some implementations seem to use this Group 40 write / different Group ID read scheme?  (For example, backwards compatibility with older SCADA systems, legacy "that's just how it is", etc.)

Thanks so much!

Chris

[Adam Crain]

Hi Chris,

On Jun 14, 4:23 pm, Christopher Verges <chris.ver...@gmail.com> wrote:
> Hi OpenDNP3 gurus,
>
> I'm looking into two different features of DNP3 and am need a bit of
> pointing towards the answer.  The questions:
>
> 1. Does the OpenDNP3 library support exception reporting of analog points by
> deadband? If so, how do you configure such a point?  (Group 34 objects?)

The stack does support deadbanding (i.e. only reporting analog changes
by a certain threshold). Group 34 objects are used to configure
deadbands remotely, and I believe the slave side supports these write
requests, but probably not the read request. The master side doesn't
currrently provide the ability to write them. (this is all consistent
with Level2 functionality if I'm not mistaken)

To set the dead staticallyThe project is part of the [http://
www.totalgrid.org/ Total Grid Community] sponsored by [http://
www.greenenergycorp.com Green Energy Corp].

Deadbands are configured statically on the slave via DeviceTemplate
class on a per point basis (and it's corresponding XML fields on the
test set.

>
> 2. In dealing with Group 40 "analog outputs" object, are these objects both
> read and write capable?  (That is, if I write a value to a Group 40 object,
> can I query that same object to see the value that was just written?)

No. Analog outputs are just like Binary Output objects, write only.
The actual analog controls is actuall Group 41VarX. Shadow copies are
used to report feedback and they are Group40Var1. Until recently these
objects did not report by exception in the specificaiton so many
implementers
choose to map the feedback onto standard analogs Group3XVarY objects.

>
> 2(a). If the Group 40 objects are write-only (i.e. cannot be read), then is
> it typical to have a "shadow copy" available as an analog input under a
> different Group number?
>
> 2(b). If the Group 40 objects are read/write capable, do you have any
> insights into why some implementations seem to use this Group 40 write /
> different Group ID read scheme?  (For example, backwards compatibility with
> older SCADA systems, legacy "that's just how it is", etc.)

I believe that people use the analog output status / analog
inconsistently as feedback for the analog outputs because of the
previously mentioned lag in the spec for analog output status event
reporting.

>
> Thanks so much!
>
> Chris