Beckhoff TwinCAT 2 TX1200, Руководство пользователя

Страница: 56 / 80

Programming
TX1200 56 Version: 1.1
6.2.20 MP_VAV
This function block is used to control and monitor a volume flow controller.
MP_Address is used to specify the MP-Bus device with which the function block is to communicate. bStart
activates communication with the MP-Bus device. bBusy indicates that the function block is active. If bStart
remains TRUE, the device is addressed cyclically with a period specified by the time in TMPolling . The time
should be set longer than 1 s. bError is used to indicate an error in communication with the actuator. The
type of the error can be read with iErrorID .
A positive edge at bReset clears any pending error messages from the actuator. This resets errors that
affect the output variables bErr_MecOcld , bErr_ActHunt and bErrMecTrv . If the error itself is still present,
the actuator will set these error bits again.
SetPoint is used to adjust the volume flow rate from 0...100 %. The current position of the damper can be
read through ActValue .
If a sensor is connected to the actuator, its type is to be indicated in iSensorTyp . If no sensor is connected,
the value "0" should be entered, or the variable left open. A digital sensor should be parameterized with "1".
The state of the sensor can be queried through
bMP_Sensor_Digi . Analog sensors "2...6" are output in
variable iMP_Sensor_Analog .
A positive edge at the bOpen or bClose inputs opens or closes the damper of the actuator. A negative edge
at these two inputs clears the command again.
MaxVol and MinVol can be used to store a maximum and minimum volume flow rate in the actuator. A
positive edge at bSet writes the data to the actuator. You can obtain the current value from the output data
act_MaxVol and act_MinVol . The current volume flow rate is output in the AirVolume_m3h variable.
VAR_INPUT
MP_Address : USINT := 1;
bStart : BOOL;
bSet : BOOL;
bOpen : BOOL;
bClose : BOOL;
bReset : BOOL;
iSensorTyp : INT;
SetPoint : USINT;
MaxVol : WORD;
MinVol : WORD;
strDataKL6771 : DataKL6771;
TMpolling : TIME := t#10s;
MP_Address: MP-Bus address of the slave.
bStart: a positive edge starts the function block. If this remains continuously TRUE, the function block will be
activated cyclically with a period specified by the time in TMPolling .
bSet: a positive edge writes the MaxVol and MinVol data to the actuator.