How to read specific BACnet object without discover and broadcast?

Hi all,

Sorry if my question could seems strange (how I'm using BACnet) but I did not found on the documentation how to read BACnet objects with Unicast pacquet.

I have to read 2 objects present_value from 2 devices that are not on the same subnet than my Ignition server. There is no BBMD.

I can ping devices, I can use Yabe or BACeye on the server to read object but how should i setup my tags on Ignition please?

Of course, my devices on OPC UA device are uninitialized cause the "who-is" pacquet never receive "i-am" answer.

I tried to create a tag with the correct BACnet mapping but I get an Error_Configuration.

Did the Ignition BACnet driver only support discover/broadcast for BACnet ?

Thanks for your help.

I'm pretty sure this is required by Ignition to reach other BACnet subnets.

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Yes in case of UDP (who-is, COV subscription, etc... ) => All that make BACnet a nice protocol.

It seems that BACnet driver is based on UDP.
Do you know if there is a way to run TCP request. I'm seeing your name very often here, how did you managed BACnet before the dedicated driver on Ignition ?


I have not used BACnet myself. I just pay attention to others' comments here on the topic.

Okidoki :slight_smile:

Thanks for your help

@Kevin.Herron would perhaps be the man to clarify, think he did the bulk of the development of the IA BacNet driver.

A search of the forum will show others who have used it a lot (as end users).

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Most of the BACnet comms are unicast, but you won't be able to do anything until the driver is successfully initialized.

"Initialization" is basically just exchanging who-Is and i-Am messages, plus some additional messages to read the object/property lists after that.

The who-Is is sent both via broadcast and unicast directly to the configured remote address. The i-Am response can come back via either, but it has to come back somehow.

No, BACnet/IP is UDP based.

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Hello @Kevin.Herron;
Thanks for this clarification.

Sorry for the delay, vacations + covid ;(

I assume that the unicast packet are sent over TCP with the defined BACNet port number isn't it ?