05.91
21 Terms and Abbreviations
DR
Abbreviation for the right data byte of a data word; this is
the lower-order data byte of the data word.
DRF
Abbreviation for differential resolver function, interface for
handwheels
DW
Abbreviation for data word
DX
Category of data block
Dynamic signal
Signal that is reset by the PLC operating system at the
end of the cycle
ELG
Abbreviation for electronic gearbox
EM
Abbreviation for entry menu
Emergency stop
Deactivation of all NC functions by the user in an
emergency by means of a special EMERGENCY STOP
switch
EU
Abbreviation for expansion unit
Expansion unit
Subrack for I/O modules that are not inserted in the
central controller. SINUMERIK expansion units (EUs) have
a serial interface to the central controller, SIMATIC EUs
can be interfaced to the central controller with a parallel
port subject to certain preconditions (see Section 1).
F word
Word (parameter) in the part program that specifies a
feedrate
FB
Abbreviation for function block
FB package
Package of function blocks. Contains several
preconfigured function blocks with associated functions.
The FBs from FB packages are loaded in the PLC when
required and can then be called by the PLC program.
Feedrate override
Change of specified feedrate
FIFO
First in, first out; designates a software queue for jobs or
data
File transfer (FTR)
Data transfer between host computer and NC
Fixed-point number
Number format; see "PLC 135 WB Planning Guide", own
documentation
Flag area
Bit-addressable memory area used for temporary
(dynamic) and retentive flags. Parts of the memory area
are saved in a kind of stack in the event of program
interrupts.
Flag word
Two consecutive bytes in the flag area, starting at an
even address
© Siemens AG 1991 All Rights Reserved 6ZB5 410-0HE02
21–3
SINUMERIK 880 (PJ)