How to read a specific Object Instance inside a Device Instance

[fromnowhereuser]

Node Version: X.Y.Z

Node BACstack Version: X.Y.Z

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• [ x ] Feature Request
• [ x ] Question

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Feature Request / Question

Hello all, my questio is quite simple, i wanty to read a property (present value for ex) so, the propertyID: 85
To test, i have downloaded this: http://bacnet.sourceforge.net/
and i run this command to query a property:
./bacrp --mac 192.168.1.12 1012 2 13 present-value
or
./bacrp --mac 192.168.1.12 1012 2 13 85

192.168.1.12
is ip of the device i want to query

1012
is the DEVICE instance

2
is the object-type (like analog, etc...)

13
os the OBJECT instance

property
85, for present value according to bacnet protocol.

According to the node-bacstack doc, to read a property, i need to:
const bacnet = require('node-bacnet');
const client = new bacnet();

client.readProperty('192.168.1.43', {type: 8, instance: 44301}, 28, (err, value) => {
console.log('value: ', value);
});

But, i cant put the OBJECT instance somewhere, so... what can i do ? I am quite stuck and i feel i am doing something wrong.. but i can see where

[rristov60]

Hi, so I assume you want to read a specific object property from a device. In the given example above you are reading the Description of Device object.

Let me elaborate.

The read property function has the following structure:

client.readProperty(deviceIPAddress, { type: objectType, instance: objectInstance }, propertyToRead, (err, value) => {
     console.log('value:', value);
});

The actual device is also considered as an object of type 8 with instance 44301 which is the default instance. This instance essentially is deviceID ( each device has unique ID ), so you can either use the default one or use the actual device ID. Property id: 28 is the description property of the object.

So basically you use the same structure for any object ( as mentioned above the device is an object as well ). The code for the object you gave as an example that you want to read would look like the following:

const bacnet = require('node-bacnet');
const client = new bacnet();

const deviceIp = '192.168.1.12';
const readObject = {
    objectId: {
        type: 2,
        instance: 13
    },
    property: 85
}

client.readProperty(deviceIp, readObject.objectId, readObject.property, (err, value) => {
    console.log('value: ', value);
});

Hope this helps :))