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Bacnet status flags
#1
Hi

I'm struggling with the integration of the bacnet-objects from the LM5 in the SCADA-system.
In the SCADA-systems tag-explorer, several of the bacent-tags (imported from EDE-file) from LM5 has the status-flag 'overridden' i set.
The present-value property seems to update, but the tag/visu in the SCADA then report a deviation......

Has anybody seen this behavior or have an idea of how to fix this????

And for my own understanding: could you give me some info about the COV-property? (how to use, limitations and so on...)

Eirik
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#2
Hi

Check to which priority array your scada is writing to. LM by default will write to 16 but you can change it. If your scada is writing to higher priority then yes it will be overridden and all values from LM will be in PA16 but ignored by Present Value.
Yo can clear priority array on LM by simply disabling bacnet server and enabling it again.

First exported 256 objects will have COV. If you have more then the rest must be pooled. Proper bacnet client will just deal with it out of the box.

BR
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#3
Thanks.
This behavoir is mainly on read-tags, like temp and statuses.

Will there be a shift i instances when disabling and enabling the bacnetserver?

Eirik
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#4
(14.02.2018, 09:06)eirik Wrote: Thanks.
This behavoir is mainly on read-tags, like temp and statuses.

Will there be a shift i instances when disabling and enabling the bacnetserver?

Eirik

No, each knx object has fixed bacnet instance.
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#5
I was on site today, and did some tests.
When I disabled/enabled the LM, the bacnet-objects status flags were set to 0. But at the first update of the objects on knx-bus the "overridden" got set to 1.
This is a read tag in the scada, so there is no writing to this objects. Only updated on the knx.
There are also differse between the value in the priority array 16 and the present value property of the bacnet-object. 
Also tested with YABE(yet another bacnet scanner) and wago bacnet configurator with the same result. 

I had the support from the scada-developer to have a quick look also, and they checked with wireshark. 


The status-flags appeared to be set from the lm5. 

Could anyone help me with this issue?

Eirik
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#6
Of course is set from LM as LM is the server here. Did you check if there is anything writing to any other priority array? All arrays should be null apart of the 16. Otherwise you will have override but this is how BACnet works.
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#7
Hi,

I have seen this once before on a Sauter BMS, also on the read values, what Sauter did was showing the override flag when the value in the prio array was higher then the relinquish default value.

Because the values where read only we have set the relinquish default value to the max object value and that solved the issue. Personally i don’t think it is a issue on our side but on the BMS side, our own Ecostruxure Building Operation BMS has no issues with this.

BR,

Erwin
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#8
Hi 
I've checked the priority array. All other prioritys are set to nil.
It's only values in array 16.

I'm also testing to change the relinquish default, but get an write access denied.
This is tested with both SCADA and YABE.
It also appear an write access denied when I try to change the setpoint on a KNX-thermostat.
But the object in the LM5 updates, also on the KNX-bus.

Eirik 
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#9
Hi
What scada is it?
Let's compare the PICS. As Erwin mention the issue here must be on the other side as we did lots of BACnet integration's with certified clients. It is probably similar think what Sauter. When you testing with another client make sure you first reset bacnet server as when flag is set it stays like that even when different client is connected.
BR
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#10
Thanks for the quick reply.
This forum is fantastic!!!

This is a norwegian-developed scada-system and the bacnet-integration is quite new. We have been using it with Modbus TCP, and other protocolls 'til now.
I think some of the essence in this issues, is what you, Daniel, mentioned in your post: " we did lots of BACnet integration's with certified clients."
This certification on the client is not ready yet......

I'll do some test later today with some other clients, and keep you posted if I could make some progress on this matter.
It looks like the issue as Sauter, but i can't change the relinguish default from any of my clients.
Still gets the "write access denied" from the server(lm5)

Eirik
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#11
Hi,

That is strange, RD must always be adjustable as this is the value that will be used when prio array is cleared.

It’s possible from Stuxureware to change it so i don’t know why you have issue to set it.

BR,

Erwin
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#12
Hi
Here's an update about the bacnet.

I've testet the bacnet on another prosject and discovered some strange behavior also on these two LM5's.

On this project I've didn't connect with my SCADA-system, but with two different bacnet-clients.
The Wago Bacnet-configurator and the Yet Another Bacnet Scanner.
When scanning and connecting to the LM5 then some objects returned with these properties:
Relingiush default returned the same value as the present value.
When trying to change/write to this property the "write access denied" came back.
On an update on the present value property the overridden status flag return "1".

On this project the bacnet-server has been disabled and not integrated in other systems earlier.
And are there any other programs I could use to test with?
Have been testing with 3 different clients with the same result.   Huh

Are there any difference in the bacnet integration on LM5, Spacelynk or Wiser.....?

Eirik
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#13
It's exactly the same.
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#14
I found out.
Had a spacelynk laying around which I tested, and with the same result.
All updates on an object set the flag overridden.

Still getting the write access denied on all other properties then the present value, also.

Erwin: How did you manage to change the relinguish default? In the PICS for SL/HL there are only 3 writable properties:
-Present_value
-COV_increment
-Out_of_service

Could this behavior be an result of segmentation issues?

Eirik
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#15
Write access denied error for present value can be triggered when priority is set to 6, which is reserved for minimum On/Off algorithm. It is also triggered for properties that are not writable.
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#16
Hi,

My reaction was based on some experience more then a year ago, so i just runned some tests to see what is happening. I can't update RD also anymore, but that's what we did on the Sauter project, not sure if BACnet module is changed after that. Also in my automation server the flags are triggered now.

I can also see why, as we are writing to a array property and not to the value property, so the value property gets updated from the array override, and the overridden flag is triggered. When you write directly to the value property the status flag is normal again. So there is nothing wrong, and all functions as BACnet should work, its just a logical result of writing to the array property (1 to 16). You can't set the controller to 17 (value property) like in our Ecostruxure Building MPM.

However i don't care about status flags, it's just a indicator and not a alarm or something and beside just showing the state it does nothing further..

BR,

Erwin
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#17
Hi

I agree with you, Erwin, on the matter that it's just an indicator.
But the object is not overridden, and my scada and some others I've checked is using this status flag to show if the object is "real".

I've got 14 LM5's on 5 different projects and we have build up all of our integrations of knx- and modbus-devices around LM and BACnet, so in my case this is an actual issue.
The LM5 is an amazing product and I really think this the best way to integrate different protocolls.

Eirik
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#18
Try testing it with VTS: https://sourceforge.net/projects/vts/
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#19
Thanks!
Going insite for test later today.

Eirik
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#20
Update!
I've tested the KNX-bacnet-integration with an Combridge BNG from IPAS
Tested with analog inputs, outputs and value.
The status flag on some of the objects where high on start up but went low when updated, both from KNX and scada.

Eirik
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