Siemens FM 450-1 - Basics on Calling Modes, Settings and Commands; Infinite Counting

8.3 Basics on calling modes, settings and commands
Calling modes, settings and commands
• You select modes and settings in the FM°450-1 parameter assignment screen forms.
The parameter assignment data are automatically stored on the programming device and in
the rack SDB.
Notes on installing parameter assignment screen forms and on assigning the FM°450-1
parameters can be found in the chapter "Parameter assignment (Page 37)" and, after the
software has been installed, also in the integrated Help function.
• Modes and settings are modi󹪝ed in the parameter assignment screen forms. The new mode
or setting is valid from the next time the FM 450-1 starts.
• Commands are either generated via hardware signals, which are connected to the front
connector, or by setting the relevant input parameters of the FC CNT_CTRL in the user
program to in󹪞uence the count process. The input parameters are stored as control bits in the
DB of the FC CNT_CTRL.
Control and status bits in the DB
In addition to the control bits, there are status bits in the DB which signalize the status of the
count process. The control and status bits are each allocated two bytes in the DB (see the chapter
"Assignment of the DB (Page 87)".)
Transferring control and status bits
You transfer control and status bits between the CPU and module with the FC°CNT_CTRL, which
you must integrate into your user program:
Use symbolic names for the control and status bits in the user program. The symbolic names are
used in this chapter in the description of the FC.
The exact description of the FC CNT_CTRL is to be found in the chapter "Program (Page 39)"; the
DB assignments are to be found in the chapter "Assignment of the DB (Page 87)".
8.4 In󹪝nite counting
Overview
In this mode an FM 450-1 counter counts in󹪝nitely from the current counter status:
• When counting up, if the counter reaches the upper count limit and a further count pulse
comes, it jumps to the lower limit and continues counting from there without any pulse loss.
• When counting down, if the counter reaches the lower count limit and a further count pulse
comes, it jumps to the upper limit and continues counting from there without any pulse
loss.
Modes, settings, parameters and commands
8.4 In󹪝nite counting
Counter module FM 450-1
Equipment Manual, 03/2022, A5E03648739-AC 59