Count Range - Siemens FM 450-1 Equipment Manual

Modes, settings, parameters and commands

8.7 Count range

Terminating counting process with the gate stop function
In addition you can terminate the counting process at any time using the gate stop function. For
this purpose you set the GATE_STP input parameter of the FC CNT_CTRL.
8.7 Count range
Introduction
There is a 32°bit-wide count register on the module. With the count range you specify if the
module counts only in the positive range or if the 32nd°bit is interpreted as a sign bit and hence
negative numbers can be represented. This section describes these two count ranges, "0 to
+32 bits" and "-31 to +31 bits".
Count ranges
The FM 450-1 counts within different limits in the count ranges 0 to +32 bits and -31 to +31 bits.
In each case an overflow or an underflow is identified at the range limits.
In the "-31 to +31 bits" count mode, the counter status is represented in the two's complement.
Count range
0 to +32 bits 0 to 4 294 967 295
1)
0 to FFFF FFFFH
-31 to +31 bit -2 147 483 648 to 2 147
483 647
8000 0000H to
7FFF FFFFH
In this count range, you can only specify and evaluate values in hexadecimal.
1)
Overflow, underflow and zero crossing
A bit is set in the DB of FC°CNT_CTRL for both count limits in the case of overflow and underflow
(see section "Assignment of the DB (Page 87)").
In the "-31 to +31 bit" count range, a bit is similarly set in the DB on a zero crossing.
In the "0 to +32 bit" count range, an overflow or underflow, depending on the direction of
counting, is additionally indicated on a zero crossing.
Event
Overflow
Underflow
Zero crossing
64
Overflow
When the counter status changes from
4 294 967 295 to 0
When the counter status changes from
+2 147 483 647 to -2 147 483 648
Underflow
When the counter status changes from
0°to 4 294 967 295
When the counter status changes from
-2 147 483 648 to +2 147 483 647
Bit in the DB
STS_OFLW is set
STS_UFLW is set
STS_ZERO is set
Equipment Manual, 03/2022, A5E03648739-AC
Counter module FM 450-1