SIMATIC WinCC Open Architecture Forum

Hello,
can somebody explain what is a BacNet object ? I have found that a BacNet driver license expands a Server with BacNet capability but there is a limit of 5000 objects per server.
What's a BacNet Object ? When I pulled data out from a single BacNet device I get 140 lines of data that I don't know how to define. Are those objects ? Or the object is the BacNet controller which carries the IP address ?
Thank You,
Walter

Hello Walter,

The BACnet standard defines a number of standardized object types (Analog Input, Binary Output, etc.), whereby each object type has particular properties (Object_Identifier, Present_Value, etc.).

A "BACnet object" is a single object instance of a specific object type.

When you export data from a single BACnet device, you usually export the data in an EDE file. Then each line of the EDE file corresponds to a single BACnet object.


Please note that you will need for each property of a BACnet object which should be mapped to a WinCC OA data point element an _address config, whereby this _address config corresponds to one I/O.

So when you engineer 5.000 BACnet objects on a WinCC OA server, you will need an WinCC OA Server license with approximately 100.000 I/O, because each BACnet object has on average (depending on the actual object type) about 20 properties (_address configs respectively I/O).


With best regards,
Christian Boehm

Hi,
I'm interested in extend information about BacNet driver.
My project details:
Bacnet objects come from protocol routers (20pcs), all objects have only 2 properties 'present value' and 'reliability'.
Project will have around 13.000 (objects).
I've planned to use many poll groups, with times around 20 - 60 seconds
I'm not using BACnet Object Library, Faceplates, Engineering Env, and BacNet Browser

What i need to know:
with such simple objects, max number of Bacnet Objects is still 5000?
is 5000 object per server hard limit?
can additional drivers (managers) in single server extend limit?

one driver is to only one BacNet network, but in BacNet driver configuration, static address binding, allow to define network ID, for each device?

what is max number of drivers per server?
what is max number of devices per driver?
what is max number of objects per device?

Are there other options apart from distributed configuration?
Custom driver?

Hallo,

the 5000 objects per server is no hard limit. In your case, where you are interested in only 2 properties of each object you can go (far) beyond this.
Of course you have your I/O license limit in shield file, which corresponds to BACnet properties (i.e. peripheral addresses).
A number of 13000 object, which means 26000 properties for one BACnet driver will be no problem in your case.
Especially if your poll intervals are in the range of 20-60s.

Your questions concerning the maximum numbers are not so easy to answer, because it depends on different
requirements of the specific project (e.g. data update rates).

*You can start up to 255 drivers per server but if your are bound on the BACnet UDP Port 47808 they have to be distributed
to several machines.
*One driver can handle several hundred devices. There is no hard limit. The limit is given due to system resources.
*There is also no hard limit for the objects in one device, but if a device is very big it might be that reading all data from a
device last rather long.

best regards

Andreas

Hello,

If it is possible I want to ask some questions regarding the same topic.

1) If I have the same case of choosing only two properties ( present value , status flags ) but the poll interval is (5 seconds).would be the same as using as an example 15000 object ( 30000 property) over the same bacnet driver .?

2) You have said its possible to use 255 drivers per server , so is there any consequence of having all the 255 drivers with fully number of objects for each driver ( 5000 object * 255) driver .

3) As well one the same server could i use multiple drivers of the same type but with different port number as example can i use 10 bacnet drivers on the same server. and how is it possible to change the port number ?.

Thank you very much for your help

IBRAHIM AL ALI wrote:

1) If I have the same case of choosing only two properties ( present value , status flags ) but the poll interval is (5 seconds).would be the same as using as an example 15000 object ( 30000 property) over the same bacnet driver .?

I do not understand your question.
Can you please describe it more detailed.

2) You have said its possible to use 255 drivers per server , so is there any consequence of having all the 255 drivers with fully number of objects for each driver ( 5000 object * 255) driver .

If you 5000 objects for every driver and 255 drivers are started you will have 1275000 objects.
Depending on the number of addresses needed for one object you will have a high number of addresses in your project. If one object has 2 properties you will have 2550000 addresses.
If a poll interval of 5 seconds is used you will have 510.000 value changes per second which is quite a lot and probably too much for the WinCC OA system, depending on the smoothing settings.

3) As well one the same server could i use multiple drivers of the same type but with different port number as example can i use 10 bacnet drivers on the same server. and how is it possible to change the port number ?.

With the config entry net = "configuration" you can define the port number used by the driver.
For detailed information concerning the configuration please have a look at the WinCC OA documentation.

Best Regards
Leopold Knipp
Senior Support Specialist

Good day

I have a question regarding the bacnet engineering explorer as it creates each object with all associated bacnet properties as present value , status flags , out of service , priority arrays . Then I have asked about the bacnet properties I/O count and the answer was that each property will be listed as one I/O. But here I have one concern regarding some properties as status flags would it be compressed and counted as one I/O or it will be counted as separate four I/Os ,the same is applied to the 16 value of the dynamic tag of priority arrays .

Regards

Hello,
Each active address config (Input or output) counts as an IO in WinCC OA . A Bidirectional address configs (input and ouput at the same time) counts as 2 IO´s.
When using the WinCC OA standard BACNET library, than address-configs are created automatically on several BACNET objects elements (e.g. present value , status flags , out of service , priority arrays …). Each Bacnet property with an active address configs counts as an IO. The number of created address-configs per Bacnet Object depends on its type.
In order to reduce the number of IOs in your application, you have the possibility to deactivate address configs on not relevant Bacnet properties (please do this on the MasterDP from the Bacnet Object and not directly on the DP- instances!).

BR,
Mousser

Hi Mousser ,

I think you didn't get the question well . As well I have tried the panel that is in the lab files ((I/O Count)), and tested it as i have changed the config of address to inactive of a tag that has config input and output then it discounted only one I/O .

but my question was about some properties as status flags wouldn't be counted as separate 4 1/Os as the status flags represents internally four Boolean flags(out of service , fault , alarm, override).

Regards

Hello,

Are you talking about the DPelement *.property.Status_Flags, which exists in different WinCC OA Bacnet objects.
this is 1 DPelement with an Imput address-config: it´s counted as 1 IO.

If your question is still not answered, than please send us the names of the Bacnet Object (DpType name) and the DPelements (properties) you are talking about.


BR,
Mousser.