Siemens simatic s7-400 FM 450-1, User Manual, Page: 10 / 130

Product Overview
1.5 The FM 450-1 software
Counter module FM 450-1
10
Manual, 02/2014, A5E03648739-02
1.2 Properties
Properties
The FM 450-1 is a fast counter module to be used in the S7-400 automation system. There
are two counters on the module which can work in the following counting ranges as required:
● 0 to 4 294 967 295 (0 to 2
32
- 1)
● - 2 147 483 648 to + 2 147 483 647 (-2
31
to 2
31
- 1).
The maximum input frequency of the counter signals is up to 500 kHz depending on the
encoder signal.
The FM 450-1 can be used for the following counting tasks:
● Continuous counting
● Single counting
● Periodic counting
You can start and stop the count either via the user program (software gate) or via external
signals (hardware gate).
Comparison values
You can store two comparison values per counter on the module; they are assigned to the
two corresponding outputs on the module. If the counter status reaches one of the
comparison values, then the output assigned to it can be set so that it triggers control
operations directly in the process.
Load value
You can determine an initial value (load value) for each counter on the FM 450-1 The
counter is set at the initial value if a software or hardware-related signal to the module comes
up.
Hardware interrupts
When comparison values are reached, for overflow, underflow and/or for zero crossing of a
counter, the FM 450-1 can trigger a Hardware interrupt.