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Chapter 6 – Communication
The Control Word and
the Status Word
References
Actual Values
6-4
The Control Word is the principal means for controlling the drive from a
fieldbus system. It is sent by the fieldbus master station to the drive, the
adapter module acting as a transparent link. The drive switches
between its states according to the bit-coded instructions on the
Control Word. The Status Word is a word containing status information,
sent by the drive to the master station. The contents of both the Control
and Status Words are explained in the drive documentation.
The Control and Status Words are not altered by the NCSA-01 in any
way, excepting Bit 15 of the Status Word, which is turned on by the
module in case of an error in the DDCS communication between the
module and the drive.
References are 16-bit words containing a sign bit and a 15-bit integer.
A negative reference (indicating reversed direction of rotation) is
formed by calculating the two's complement from the corresponding
positive reference.
ABB drives can receive control information from multiple sources
including analogue and digital inputs, the drive control panel and a
communication module (e.g. NCSA-01). In order to have the drive
controlled through Interbus-S, the communication module must be
defined as the source for control information, eg. Reference. The
scaling of the integer received from the master as Reference is drive-
specific. See its Programming Manual for available control source
selections and Reference scaling factors.
Actual Values are 16-bit words containing information on the operation
of the drive. The functions to be monitored are selected with a drive
parameter. The scaling of the integers sent to the master as Actual
Values depends on the selected function. Please refer to the drive
documentation.
NCSA-01 Installation and Start-up Guide
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