Digital Input BACnet Objects
BI - Digital Input Object Description (Binary Input: 0-11, 12-23 for MAX Modules)
Each of the digital inputs in all types of modules is represented on the BACnet network as the BACnet Binary Input object with the following properties:
Dynamically createable: no, dynamically deletable: no.
Property Name | Required | Proprietary | Writable | Property ID | Data Type | Description |
|---|---|---|---|---|---|---|
OBJECT_IDENTIFIER | Yes | From BI:0 to BI:11 and BI:12 to BI:23 for 24I and 24I-IP modules | ||||
OBJECT_NAME | Yes | BI-x | ||||
OBJECT_TYPE | Yes | |||||
PRESENT_VALUE | Yes | PRESENT_VALUE property | ||||
STATUS_FLAGS | Yes | |||||
EVENT_STATE | Yes | |||||
OUT_OF_SERVICE | Yes | OUT OF SERVICE property | ||||
POLARITY | Yes | |||||
UNITS | Yes | |||||
COUNTER * | Yes | Yes | 3001 | Unsigned |
Note: Object’s additional properties are saved to maintain the backwards compatibility with the older firmware version. In the new firmware version, each of the properties has a corresponding BACnet object.
PRESENT_VALUE Property
The property contains the status of the digital inputs. Shorting the input to G0 sets the value to 1.
Binary Input COV
In the firmware version above 4.0, multiprotocol I/O modules support COV (change of value). It means that the module automatically sends digital input value after every change.
OUT OF SERVICE Property
If the Out Of Service is false, the Present Value property represents the actual value read from the input. Setting the Out Of Service property to true, stops updating the Present Value property from the physical input, and allows for entering a custom value into the Present Value property.
WARNING!
If the Out Of Service property is false, the Present Value property cannot be overridden, and the module will return an error message: “Write Access Denied”.
BIA COUNTER Object (Accumulator: 0-11, 12-23 for MAX Modules)
The object contains the number of counted pulses represented by the Accumulator Value BACnet object. This value is also saved in the non-volatile memory, so the information is stored even after the power cycle finishes. It is possible to reset the counter by entering 0 to the Present Value property of this object.
This value is also available as the BACnet BI Binary Input object property number 3001.
BI COUNTER Object (Analog Value: 2-13, 42-53 for MAX Modules)
The object contains the number of counted pulses identical to the Accumulator BACnet object but stored as the Analog Value object. Not every system supports the accumulator type object, therefore additional objects have been created for the counters. The Analog Value has one drawback–odd values above 16777216 are rounded down by 1. For example, 16777216 + 1 is still displayed as 16777216, but 16777216 + 2 is displayed properly as 16777218.