The Ref In function block makes it easier to get a value from a BACnet object on a remote BACnet device. RefIn subscribes to or reads the BACnet object of the remote BACnet device on a regular basis once it has been correctly mapped to the remote BACnet object.
Figure 1: RefIn - Function Block |
Figure 2: RefIn - Property Sheet |
Inputs
Input Name |
Description |
NA |
NA |
Table 1: Inputs of RefIn Function
Outputs
Output Name |
Description |
Out |
When Out of Service is "false"-Out is the last read value of the linked BACnet object property. When Out of Service is "true"-Out retains the last value, it had before Out Of Service is set to True. |
Status Flags |
Displays the status of this function block. It can be any one or a Or combination of the following values: 2 - Fault 8 - Out of Service Example: A value of 2 means the function block is in In Alarm state. |
Units |
Displays the unit of the value retrieved from the remote BACnet object. |
Out Of Service |
It shows the whether the function block is in out of service state or not. Out of Service is modifiable over BACnet. Setting Out Of Service to true, stops retrieval of value from the linked BACnet object of the remote BACnet device. |
Table 2: Output of RefIn Function
Parameters
Input Name |
Description |
Device Instance |
Define the remote BACnet device instance, whose BACnet object need to be linked to this RefIn. |
Object Type |
Define the type of the BACnet object need to be linked. Nine types of Object Type are presently supported:
|
Object Instance |
Define the instance number of the BACnet object to be linked to this RefIn. |
Property Id |
Define the property id to be read. Presently it is only Present Value that is supported. |
Poll Rate |
Mode - Defines whether RefIn shall subscribe COV for the linked objects property value or it would do Polling. Poll Rate - Define how frequently (in minutes) RefIn should poll for this linked objects property value, when Mode is defined as Polling. If Mode is defined as COV, RefIn subscribes for COV (change of value) of the property value for the linked BACnet object. If successful the linked object property value changes, linked object itself asynchronusly sends COV updates to RefIn. In this mode RefIn renews its COV subscription every 15 minutes. If COV subscription request fails, RefIn automatically fallsback to Polling mode internally. If Mode is defined as Polling,RefIn reads the property value of the linked BACnet object every poll interval as defined in Poll Rate. |
Initial Value |
Define the initial value at controller startup that should show up on Out, before the first successful poll. |
Bacnet Object Instance |
It shows the instance number of this BACnet object. |
Out Save |
Master Sync Enabled: If you set it to "true" the last output will be set as output for one cycle after the controller restarts. The application can use it to return to the same state before the controller restart. Out: To enable or disable the Out feature. |
Table 3: Parameter of RefIn Function
Examples
Figure 3: Example Refln Function Block
Refer to General Description for general information about IRMN4 Function Blocks.