Function blocks and program structure 25
DriveRef
The DriveRef (DRIVE_DATA) variable must be connected to
all function blocks of the drive to exchange data.
Main components of the example program
Modbus RTU communication function block (FB_COM)
FB_COM is a communication function block for
Modbus RTU. It controls the communication to
the drive and cyclically reads the status word,
actual speed, and up to seven more parameters
from the drive. When there are changes in the
control word or the speed reference values, the
function block writes the new values in the drive.
Refer to the online help for a detailed description
of the function block and its inputs and outputs. For additional instructions, see the below
sections in this manual:
• You can set the slave address as described in Configuring the slave address of the
drive on page 17.
• If more than one drive is used, the LineCom1 variable in the LINE_TOKEN input must
be declared as global. See Information on LineCom1 as a global variable on page 18.
• For a description of the DRIVE_DATA variable DriveRef, see DriveRef on page 25.
• If more parameters are to be read from the drive, adjust NVAR_READ and set the
parameters (53.10…53.17) in the drive. See Configuring parameters to be read from
the drive on page 21.
Basic control block (FB_BASIC CONTROL)
The FB_BASIC_CONTROL function block is
used for basic control of the drive, including
speed scaling of the actual speed and
reference value to rpm or 0.1 Hz.
The FB_BASIC CONTROL function block is
the default control block in the example
project. It is interchangeable with the function
blocks presented in Other control blocks
below. A drive may have one active control
block.
See the online help for detailed information on the inputs and outputs of the function block.
See Using the online help in CoDeSys on page 15 for information on the use of the online
help.
The function block functions only with the ABB Drives profile.
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