Siemens simatic s7-400 FM 450-1 - Page 124

Glossary
Counter module FM 450-1
124 Manual, 02/2014, A5E03648739-02
Incremental encoder
Incremental encoders are used to record distance, position, velocity, speed or weight units
by counting small increments.
Increments per encoder revolution
Defines the number of increments the encoder outputs per revolution.
OD
The "output disable" (OD) signal is used in STOP and HOLD state to force all modules of an
S7 automation system to safe state. A safe state could be: all outputs are shut off, or
supplied with a substitution value.
Power control
The power control unit controls the motor; its simplest form is a contactor relay circuit.
Proximity switch
A simple BERO switch, without directional information. The device returns only a single
count signal. The counter records only the positive edges at signal A. The count direction is
user-specific.
Pulse duration
The pulse duration setting defines the minimum on time of an output.
Push-pull
Push-pull output of an encoder; supplies an active low signal to 0 V (ground) and an active
high signal to +24 V.
Quadruple evaluation
In this mode, the module evaluates all pulse edges at the tracks A and B of an incremental
encoder.
SFC
An SFC (system function) is an integrated function of the CPU operating system. The SFC
can be called in the STEP 7 user program as required.
Single evaluation
Refers to a the evaluation of positive edges of the pulses at track A of an incremental
encoder.