FB_BACnet_Accumulator_RAW_R6

FB_BACnet_Accumulator_RAW_R6 1:

Application

The function block can be used for read and write access to a BACnet object of type Accumulator (ACC).

In contrast to the standard and _EX versions of the block, the current counter value (Present_Value) and the state of the property Reliablitity are provided by function block inputs, not directly by the IO hardware. For example, the state of a counter input can be mapped from a sub-bus system in PLC code to a BACnet object (signal conversion from sub-bus systems or virtual data points to BACnet, see Example).

VAR_INPUT

nPV               : UDINT;
nReliability      : WORD;
bOutOfServiceOut  : BOOL;

nPV: Value that is written directly to the Property Present_Value.

nReliability: Input sets the appropriate state of the property Reliability. See BACnet specification DIN EN ISO 16484-5 for BACnet object Accumulator and property Reliability.

bOutOfServiceOut: TRUE sets the object state to out_of_service. See BACnet specification DIN EN ISO 16484-5 for BACnet object Accumulator and property Status_Flags.

VAR_OUPUT

bReady         : BOOL;
nPresentValue  : UDINT;
nMaxPV         : UDINT;
bOverridden    : BOOL;
bOutOfService  : BOOL;
bFault         : BOOL;
bInAlarm      : BOOL;
bOverRange    : BOOL;
bUnderRange   : BOOL;
bNoSensor     : BOOL;
bOpenLoop     : BOOL;
bShortedLoop  : BOOL;
bOtherFault   : BOOL;
eEventState   : E_BACNETEVENTSTATE;
bError        : BOOL;
nErrorId      : UINT;

bReady: Notification of general readiness. If this output is set, the other status outputs are valid (PresentValue, Overridden ...). If the output is FALSE, the corresponding function block FB_BACnet_Device does not report "Operational", or the block instance was not linked correctly in the TwinCAT System Manager.

nPresentValue: Current value of the BACnet object (see also BACnet specification DIN EN ISO 16484-5 for BACnet object Accumulator and property Present_value).

nMaxPV: Current value of the property Max_Pres_Value of the BACnet object (see also BACnet specification DIN EN ISO 16484-5 for BACnet object Accumulator and property Max_Pres_Value).

bOverride, bOutOfService, bFault, bInAlarm: See BACnet specification DIN EN ISO 16484-5 for BACnet object Accumulator and property Status_Flags.

bOverRange, bUnderRange, bNoSensor, bOpenLoop, bShortedLoop, bOtherFault: See BACnet specification DIN EN ISO 16484-5 for BACnet object Accumulator and property Reliability.

eEventState: See BACnet specification DIN EN ISO 16484-5 for BACnet object Accumulator and property Event_State.

bError: An error is pending.

nErrorId: see global constants BACnet_Globals.

VAR_IN_OUT

Device        : FB_BACnet_Device;

Device: Specification of the instance of the local corresponding BACnet server block. For each BACnet adapter one BACnet server is possible. See FB_BACnet_Adapter and FB_BACnet_Device for further information.

Example

The following example illustrates the implementation of a digital pulse signal on a BACnet object of type Accumulator.

FB_BACnet_Accumulator_RAW_R6 2: — Fig. 1: Example for the implementation of a pulse signal in the BACnet object Accumulator in the PLC program.

The BACnet object records the count value at the input nPV. An overflow of the UDINT value occurs when a maximum value is set or depending on data type. Further information is provided by the input diPulseOk. This input indicates that the pulse-generating side (e.g. an external counter) is ready.