Siemens FM 450-1 - Glossary

Glossary
Asymmetrical signals
Refers to two pulse sequences, phase-shifted by 90°, and with zero mark signal where applicable.
Con󹪝guration
Assignment of modules to racks, slots and addresses. Users con󹪝guring the hardware 󹪝ll out a
con󹪝guration table in STEP 7.
Double evaluation
In this mode, the module evaluates all positive edges of the pulses at track A and B of an
incremental encoder.
Encoders
Encoders are used to for the precise recording of rectangular signals re󹪞ecting distances,
positions, velocity, speed, dimensions, etc.
Encoders with asymmetrical output signals
These encoders return two di󹪜erential pulse sequences with 90° phase-shift, including a zero
mark signal where applicable.
Encoders with symmetrical output signals
These encoders return two di󹪜erential pulse sequences with 90° phase-shift, including inverted
signals to form a zero mark as required.
Function (FC)
According to IEC 1131-3 notations, this is a code block which does not contain static data. A
function supports the transfer of parameters in a user program. Functions are thus particularly
suitable for programming complex, recurrent functions
Function module (FM)
A module which relieves the CPU of the S7 automation system of process signal processing tasks
which are critical in time or memory-intensive. As a rule, FMs use the internal communication
bus for high-speed data exchange with the CPU. Examples of FM applications: Counting,
positioning, controlling
Counter module FM 450-1
Equipment Manual, 03/2022, A5E03648739-AC 111