Siemens SIMATIC S7 System Manual page 272

Program instructions
7.6 Counters
HSC0
SM37.0
SM37.2
* The default setting of the reset input is active high, and the AB quadrature phase counting rate is 4x
(or four times the input clock frequency).
Example: High-speed counter definition
LAD
MAIN
HSC instruction enables counters, sets counting direction, and loads preset/current count values
The HSC instruction uses the control byte during execution. After you assign the counter and
the counter mode, you can program the dynamic parameters of the counter. Each high-
speed counter has a control byte in SM memory that allows the following actions:
● Enabling or disabling the counter
● Controlling the direction (modes 0 and 1 only), or the initial counting direction for all other
modes
● Loading the current value
● Loading the preset value
272
HSC1 HSC2 HSC3
Not SM57.0
support- support-
ed
Not SM57.2
support- support-
ed
On the first scan:
1. Select the reset input to be active
2. Configure HSC0 for AB quadrature
HSC4 HSC5
Not SM147.0 SM157.0 Active level control bit for Reset:
ed
Not SM147.2 SM157.2 Counting rate selection for AB
ed
high and select 4x mode.
phase with reset input (mode 10).
System Manual, V2.3, 07/2017, A5E03822230-AF
Description (used only when
HDEF is executed)
0 = Reset is active high
•
1 = Reset is active low
•
quadrature phase counters
0 = 4X counting rate
•
1 = 1X counting rate
•
STL
Network 1
LD SM0.1
MOVB 16#F8, SMB37
HDEF 0, 10
S7-200 SMART
*
:*