Siemens Simatic S7 Series

Program instructions
7.6 Counters
S7-200 SMART
220 System Manual, 09/2015, A5E03822230-AC
7.6.2
High-speed counter instructions
High-speed counters can count high-speed events that cannot be controlled by standard
counters. Standard counters operate at a slower rate that is limited by the PLC scan time.
You can use the HDEF and HSC instructions and create your own HSC routines, or you can
simplify the programming tasks by using the High Speed Counter wizard.
LAD / FBD
STL
Description
HDEF HSC, MODE
The High-Speed Counter Definition instruction (HDEF) selects the operating
mode of a specific high-speed counter (HSC0-3). The mode selection de-
fines the clock, direction, and reset functions of the high-speed counter.
You must use one High-Speed Counter Definition instruction for each of up
to four active high-speed counters.
HSC N
The High-Speed Counter (HSC) instruction configures and controls the high-
speed counter, based on the state of the HSC special memory bits. The
parameter N specifies the high-speed counter number.
The high-speed counters can be configured for up to eight different modes of
operation.
Each counter has dedicated inputs for clocks, direction control, and reset
where these functions are supported. In AB quadrature phase, you can se-
lect one times (1x) or four times (4x) the maximum counting rate. All coun-
ters run at maximum rates without interfering with one another.
Error conditions with ENO = 0
SM bits affected
HDEF:
• 0003H Input point conflict
• 0004H Illegal instruction in interrupt
• 000AH HSC redefinition
• 0016H Attempted to use HSC or Edge
Interrupt on Input that is allocated for
use by Motion Functionality
• 0090H Invalid HSC number
HSC:
• 0001H HSC before HDEF
• 0005H Simultaneous
HSC/PLS
• 0090H Invalid HSC number
None
Input / output
Data type
Operand
HSC
BYTE
HSC number constant (0, 1, 2, or 3)
MODE
BYTE
Mode number constant: Eight possible modes (0, 1, 3, 4, 6, 7, 9, or 10)
N
WORD
HSC number constant (0, 1, 2, or 3)