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BACnet - BACnet slave and modbus config file

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Hi all, Let me know if this is the right forum for this posting.

I have been asked by the building automation team to have my V700 PLC communicate with their BAS.

I have a BACnet Gateway installed and they have informed me that I need to configure my BACnet as a slave.

They have provided me with a MAC of 33, Instance value of 9129 and Baud rate of 38,400 - this is all that they provided me with.

I assume that they just want to find my BACNET device and READ my 5 points of data.

Looks like I cannot use the builtin TOOL to configure the Gateway - I did try, but all they saw on their network was my instance name and MAC, they of course did not see my Instance of 9129 as the configurator configs MASTER as the default.

My question is, does someone have some solid samples of the CSV file that has to be created to address my situation ?

Thanks John


Thanks in advance.

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  • 7 months later...
  • MVP 2023

Well Alex, I went there and hunted around a bit, but the only real bit of relevance is the main statement: ' This tool will configure the BACnet getaway as BACnet master and modbus Slave. If you wish to have the getaway act as BACnet slave and modbus master the configuration file should be change manualy before downloading it to the device. "  (I have copied and pasted, so the spelling errors are actual!  I need a holiday so wouldn't mind having a getaway with a slave at present!)

I couldn't actually find anything on the page that actually says how to do this.  Even if it is a simple change in the file, it needs to be fully explained.  I am a bit incredulous that setting up the gateway via Vision etc defaults into it only being a master, with no easy "tickbox" to change this setting.  To me this is a large error that needs fixing.

cheers, Aus

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  • MVP 2023
4 hours ago, Ausman said:

This tool will configure the BACnet getaway as BACnet master

Unfortunately, this is very true and represents only half of what the tool needs to do.  The higher probability is the Unitronics device will be nothing more than a slave node in someone else's Grand Building Control System.

I have one of these belonging to a customer sitting on the floor of my BearCave (like a ManCave, only darker, smoke-filled, and prone to being a location for taking a nap) with the exact same issue - we determined after installation that we are a BACnet slave and I'm going to have to crawl through the documentation Unitronics sent me to configure it manually.  

I'll post what I come up with.

Joe T.

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  • 3 months later...
  • 1 year later...
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Does anyone have a solution for this or a file that actually works and explains what changes must be done?

I have tried to configure the gateway using the example file from https://support.unitronics.com/index.php?/selfhelp/view-article/bacnet-gateway-as-slave as a base, but it never works.

We have customers that have bought this gateway believing they can communicate with BACnet just as easy as they can with Modbus.

Unitronics help desk could not help, they just sent me the same sample files I already have.  Any help is appreciated.

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  • 1 month later...


strange thing....

The only thing I struggled with is -> when talking bacnet, if the BAS (building automation system) wants to talk to the PLC, you should consider that the PLC is to be configure as a server ! not slave....

I have here a unistream PLC with the same problem's. I use my unistream as the BAS master and want to read (and write) several bacnet objects from different "participants"

let's explain : My unistream is the master controller in the BAS, there are several devices (bacnet devices) connected (via IP) to my LAN. I want to read eg. the actual temperature from a bacnet thermostat, do some calculations and wants to write an analog value to a valve (also a bacnet object). This can not be done by the Unistream PLC ! because it only act as a server ( a stupid bacnet device). For this reason, I use KEPWARE with advanced tags option -> this software act as a smart device -> reads all bacnet participants "objects" and redirects the values from the bacnet object to the corresponding participant -> read present value object xx from bacnet device 1 and write it to present value of object yy of bacnet device 2...   tested and works fine !

(it's not a cheap solution, but it's the only software I found who can do this)

to check if you are talking bacnet, you can install "yabe" -> a free software to read all bacnet objects and see all the values...


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