BACnet send message example

[pefford]

Hi,
I am starting to work on a BACnet C# project and I initially want to start just sending a message to a controller, already programmed to react on receiving numbers 1 to 4. So, my goal would be to send from a C# code sequentially messages with the value 1...4 and see if they are properly recognized by the controller.
I downloaded the BACnet solution but I am really a bit messed up with all the different projects provided....
May you give me a start point for I am wanting to achieve first?
Thanks a lot in advance,
Paul

[gralin]

Hi @pefford. Unfortunately "send sequentially messages with the value 1...4" is not enough information to implement this in BACnet. This could be done in numerous ways and the receiving party for sure is only expecting one of them. Also, apart from the values, you also need to specify the addresses and type of objects which values you are going to send. Can you provide more details?

[pefford]

Hi @gralin . I got from the provider of the Controller following information:

WATCHDOG is a digital pulse

• Priority: 7
• Object Type: BV boolean
• DOI [Device Object Identifier]: 16003
• Object Type: BV bool, AV analog
• Instance Number: 0

ALARM TYPE

• Priority: 7
• Object Type: AV
• Present Value: Analog value from 1 to 4
• DOI [Device Object Identifier]: 16003
• Instance Number: 1

Would this be enough to point me out how to start with BACnet?
Thank you very much in advance,
Paul

[gralin]

@pefford I'm still not sure but that's a start. So it seems that your controller exposes two objects. First is a Binary Value object which represents a watchtog and second is Analog Value which represents some alarm type. I'm guessing here, that you should be able to write values 1..4 to that second object and this is what you want to do. Below code should do the trick (change the IP address to match your controller):

var client = new BacnetClient { WritePriority = 7 };
client.Start();

var controller = new BacnetAddress(BacnetAddressTypes.IP, "192.168.1.2");
var alarmObject = new BacnetObjectId(BacnetObjectTypes.OBJECT_ANALOG_VALUE, 1);

for (var alarmValue = 1; alarmValue <= 4; alarmValue++)
{
    var success = client.WritePropertyRequest(controller, alarmObject, BacnetPropertyIds.PROP_PRESENT_VALUE,
        new[] { new BacnetValue(BacnetApplicationTags.BACNET_APPLICATION_TAG_REAL, (float) alarmValue) });

    Console.WriteLine($"Write {alarmValue} result: {(success ? "SUCCESS" : "ERROR")}");
    await Task.Delay(TimeSpan.FromSeconds(1));
}

[pefford]

@gralin thanks a bunch for the piece of code where to start from.

• Where should I use the given 'DOI [Device Object Identifier]: 16003' parameter? I could only find in code the 'BaCSharpObject.PROP_OBJECT_IDENTIFIER'
• would this be correct?: var controller = new BacnetAddress(BacnetAddressTypes.IP, ipAddress, 16003);
• May I suggest you at 'Ela' to create a basic 'starting project' where newbies to BACnet like me may be able to get a step-by-step insight on how creating the objects, communicating with others, the logical structure between your classes etc?

[gralin]

Where should I use the given 'DOI [Device Object Identifier]: 16003' parameter? I could only find in code the 'BaCSharpObject.PROP_OBJECT_IDENTIFIER'

Every BACnet device needs to have one special object of type BacnetObjectTypes.OBJECT_DEVICE which holds it's unique identifier in BACnet network. You can read it if you want but it's not necessary to be able to perform the write operation.

would this be correct?: var controller = new BacnetAddress(BacnetAddressTypes.IP, ipAddress, 16003);

public BacnetAddress(BacnetAddressTypes addressType, string address = null, ushort network = 0)

16003 is your device id, not it's network

May I suggest you at 'Ela' to create a basic 'starting project' where newbies to BACnet like me may be able to get a step-by-step insight on how creating the objects, communicating with others, the logical structure between your classes etc?

I'm afraid you need to have basic knowledge about BACnet protocol to be able to use this library. You also need to be able to analyze the source code to figure out the API and how to use it. There is another repository with examples (https://github.com/ela-compil/BACnet.Examples), it's not maintained but it could be helpful.

[pefford]

Thanks