Selecting The Active State And 1X/4X Mode; Active Level For Reset, Start, And 1X/4X Control Bits - Siemens SIMATIC S7-200 System Manual

Selecting the Active State and 1x/4x Mode

Four counters have three control bits that are used to configure the active state of
the reset and start inputs and to select 1x or 4x counting modes (quadrature
counters only). These bits are located in the control byte for the respective counter
and are only used when the HDEF instruction is executed. These bits are defined
in Table 9-11.
You must set these control bits to the desired state before the HDEF instruction is
executed. Otherwise, the counter takes on the default configuration for the counter
mode selected. The default setting of the reset input and the start input are active
high, and the quadrature counting rate is 4x (or four times the input clock
frequency). Once the HDEF instruction has been executed, you cannot change the
counter setup unless you first place the CPU in the STOP mode.
Table 9-11 Active Level for Reset, Start, and 1x/4x Control Bits
HSC0 HSC1
SM37.0 SM47.0 SM57.0 SM147.0 Active level control bit for Reset:
-- SM47.1 SM57.1 --
SM37.2 SM47.2 SM57.2 SM147.2 Counting rate selection for Quadrature counters:
S7-200 Programmable Controller System Manual
A5E00066097-02
HSC2 HSC4
(used only when HDEF is executed)
0 = Reset is active high; 1 = Reset is active low
Active level control bit for Start:
0 = Start is active high; 1 = Start is active low
0 = 4X counting rate; 1 = 1X counting rate
SIMATIC Instructions
Description
9-37