Re: [Bacnet-developers] request

[Steve K. <st...@ka...>]

Hi Percy,

Sorry I didn't write sooner.  I got swamped at work today, and your 
question requires a longer answer.  I had to research it a bit since I 
have not worked with calendar and schedule objects.

> 1.      How do we write to the calendar object on the date_list object type?
> What is the type of data like  whether its bit string, character string or
> What is the type of data like  whether its bit string, character string or
> octet string?

The date_list property is a List of BACnetCalendarEntry.  It is defined as:
BACnetCalendarEntry ::= CHOICE {
       date            [0] Date,
       dateRange       [1] BACnetDateRange,
       weekNDay        [2] BACnetWeekNDay
       }

The brackets [] in the choice indicate that it is CONTEXT TAG instead of 
an APPLICATION TAG.  tag 0 date is a primitive datatype.  tag 1 
dateRange and tag 2 weekNDay are complex datatypes that will need to be 
encoded between an opening and closing tag using their tag number.  The 
data inside the opening/closing tag will be:

BACnetDateRange ::= SEQUENCE {
       StartDate       Date,
       endDate         Date
       }

StartDate and endDate will be encoded using APPLICATION TAG.

BACnetWeekNDay ::= OCTET STRING (SIZE (3))
--    first octet    month (1..14)          1 =January
--                                          13 = odd months
--                                          14 = even months
--                                          X'FF' = any month
--    second octet   weekOfMonth where:     1 = days numbered 1-7
--                                          2 = days numbered 8-14
--                                          3 = days numbered 15-21
--                                          4 = days numbered 22-28
--                                          5 = days numbered 29-31
--                                          6 = last 7 days of this month
--                                          X'FF' = any week of this month
--    third octet    dayOfWeek (1..7) where 1 = Monday
--                                          7 = Sunday
--                                          X'FF' = any day of week

The octets will be encoded as specified.

Hmmm.  I coded the BACnet stack to only handle APPLICATION tags for 
WriteProperty.  It doesn't do context data, complex data types, or 
multiple elements (values).  It will be necessary to extend the 
bacapp.c/h or wp.h/c or both to handle these.

In the case of context tags, the Object and Property will dictate the 
type.  We would need to indicate that it is context tagged, and the 
value of the context tag, and be able to store the value of the datatype 
in a way that we can retrieve it.

The bacapp_encode_application_data() call in wp.c will either need to be 
enhanced to handle the context data, or a new set of 
wp_encode_apdu/wp_decode_service_request for context and complex values 
will need to be created.

I don't have the time to implement that tonight, but I can look into it 
when I get the chance.  You could also try to implement it.

> 2.      How do we write to a schedule object ? what is the type of data?

I am out of time for tonight...

Best Regards,

Steve
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http://kargs.net/