BAC_AC_CasCtrlH_01

Application

The template is a cascade controller for the supply air humidity, consisting of a master controller for calculating the set values for humidification and dehumidification.

Interface

BAC_AC_CasCtrlH_01 1:

Plant diagram 01

Block diagram

VAR_INPUT

rRmX         : REAL; 
rSpRmX       : REAL;
udiPltStp    : UDINT; 
udiOpMod     : UDINT;

rRmX: Actual value of absolute room humidity in g/kg

rSpRmX: Room set value (dehumidify) in g/kg

udiPltStp: Steps during startup of the air-conditioning plant. See also BAC_AC_StartTH_01

udiOpMod: Plant operation mode. See also BAC_AC_OpMod_01

VAR_OUTPUT

rSpHumf     : REAL; 
rSpDeHumf   : REAL; 
rYMax       : REAL;
rYMin       : REAL;

rSpHumf: Supply air set value humidification g/kg

rSpDehumf: Supply air set value dehumidification g/kg

rYMax: Upper value of the controller output limitation

rYMin: Lower value of the controller output limitation

VAR CONSTANT

PLT_NUM    : BYTE := 1;

PLT_NUM: all alarms and events of all plant components within a controller are included in a global alarm and event list. The assignment of events and alarms to a plant is defined by the assignment of a PLT_NUM plant number.
The recording and processing of an alarm from an aggregate or a device takes place within the templates by means of the alarm function block FB_BA_Alarm.
The evaluation of the alarms of a plant, e.g. for the generation of a collective message or for plant shutdown in case of relevant faults, takes place within the template BAC_PltAlm_01 by means of the function block FB_BA_AlarmPlt.
The evaluation of different plant events within the templates of a plant, takes place within the template BAC_PltComnMsg_01 by means of the function block FB_BA_ComnMsg.

Important! The assignment and evaluation of the alarms and events of a plant can only be done correctly if all templates of a plant have the same plant number!

The plant number can be assigned in the Project Builder in the parameter menu for the templates or via a column in the Excel import.

Program description

Instance	Type	Task
X	FB_BACnetAVDisplay	The input variable rRmX is connected to the AV object. It is referenced to the actual value input of the BACnet loop object PID.
W	FB_BACnetAVDisplay	The input variable rSpRmX is connected to the AV object. It is referenced to the setpoint input of the BACnet loop object PID.
OpModPrio	FB_BA_MMUX_B08	The multiplexer defines the enable conditions of the PID master controller depending on the plant operation mode udiOpMod.
		udiOpMod		Enable cascade control
		OPMOD_AC_MANON	Manual on	TRUE
		OPMOD_AC_ON	On	TRUE
En	FB_BACnetBV1204	The BV object is used to display the controller enable in the MCL or in a local operator display
En	>=, AND	The result of this network is the PID master controller enable. The enable depends on the plant operation mode udiOpMod and the plant steps udiPltStp during startup of the ventilation system.
PID	FB_BACnetLoop1201	Master controller for a room temperature control via room supply air cascade. Supplies a simple supply air temperature setpoint.
rtrigSync	R_TRIG	Upon receipt of the controller enable En, rtrigSync triggers synchronization of the master controller PID with its input value lrSync.
Y	FB_BACnetAVSetpoint	The AV object is referenced to the control value output of the BACnet loop object PID. It indicates the supply air humidity setpoint.
TLogY	FB_BACnetTLog1201	Trend logging of the supply air humidity setpoint Y
tonDlySp	TON SEL	Upon receipt of the controller enable En, this network outputs the supply air humidity setpoint with a delay.

Version history

Version number	Comments
1.0.1	First release