FB_BACnet_RemoteCommand
The following function block is used for linking a remote BACnet object of the local BACnet client. The function block for the corresponding BACnet object is linked with the aid of process data. The data exchange with the remote BACnet server takes place via BACnet with the aid of WOC (Write-On-Change) and COV (Changes-On-Value) or via polling (not recommended).
The process data can be created manually in the BACnet object, linked manually, or they can be generated automatically via PLC automapping. The comments required for PLC automapping ( (* ~ (BACnet... | ??? | ??? ) *) ) are already included in the declaration of the function block.
Use
The function block "FB_BACnet_RemoteCommand" can be used for read and write access to a remote BACnet object of type Command (CMD). To this end the remote BACnet object was added to a local BACnet client.
VAR_INPUT
bEnablePV : BOOL;
nPV : UDINT;
bRetrigger : BOOL;
bEnablePV: Enables the value of input nPV. When the input is set to TRUE, writing takes place into the property Present_Value of the corresponding BACnet object with the value of input nPV.
If bEnablePV is set to FALSE, the process data of the mapped property Present_Value are written to 16#FFFFFFFF and thus deactivated.
nPV: Value of the property Present_Value to be written. If the value is outside the value range (see BACnet specification DIN EN ISO 16484-5 for BACnet object Command and property Present_Value), the corresponding process data is disabled, i.e. writing to the property is disabled and other BACnet services have write access to the property Present_Value.
Writing of a valid value triggers execution of the corresponding command list of the BACnet object. The value of the property Present_Value is written whenever the process data changes (i.e. change in the value of nPV with bEnablePV set or signal change from FALSE to TRUE at input bRetrigger with bEnablePV set).
bRetrigger: A rising edge at this input triggers a repeat of the write process and therefore execution of the corresponding commands of the BACnet object Command. The signal change from FALSE to TRUE corresponds to a change of the process data of the property Present_Value from x to 0 to x.
VAR_OUTPUT
bReady : BOOL;
nPresentValue : UDINT;
bAllWritesOk : BOOL;
bInProcess : BOOL;
bError : BOOL;
nErrorId : UINT;
bReady: Notification of general readiness. If this output is set, the other status outputs are valid (PresentValue, AllWritesOk, InProcess). If the output is FALSE, the associated function block "FB_BACnet_RemoteDevice" reports "not operational".
nPresentValue: Current value of the BACnet object (see also BACnet specification DIN EN ISO 16484-5 for BACnet object Command and property Present_Value).
bAllWritesOk: The last requested command list was successfully processed (see also BACnet specification DIN EN ISO 16484-5 for BACnet object Command and property All_Writes_Successful).
bInProcess: The selected command list is processed (see also BACnet specification DIN EN ISO 16484-5 for BACnet object Command and property In_Process).
bError: An error is pending.
nErrorId: Error number
0 = no error
1 = function block of the corresponding client (RemoteDevice) is not called or not called regularly enough from the PLC program.
3 = the corresponding BACnet client is not ready (bOperational = FALSE at instance of the FB_BACnet_RemoteDevice)
The error numbers can be queried as block constants via the FB instance (FB_BACnet_Remote???.nERR_xxx).
VAR_IN_OUT
RemoteDevice : FB_BACnet_RemoteDevice;
RemoteDevice: Block instance of the corresponding remote BACnet device object. The remote BACnet device object of a remote BACnet server has been added under a local BACnet client. Local client and remote server are linked via BACnet. Any number of clients can be linked via BACnet adapter. See FB_BACnet_Adapter and FB_BACnet_RemoteDevice for further information.