Counter Operations - Siemens SIMATIC S5-90U System Manual

S5-90U/S5-95U
8.1.5

Counter Operations

The programmable controller uses counter operations to handle counting jobs directly. Counters
can count up and down. The counting range is from 0 to 999 (three decades). Table 8-5 provides
an overview of the counter operations. Examples follow the table.
Operation Operand
S
R
CU
CD
ID
C
Loading a Count
Counter operations call internal counters.
When a counter is set, the word in ACCU 1 is used as a count. You must therefore first store
counts in the accumulator.
You can load a count with any of the following data types.
KC constant count
or
DW data word
IW input word
QW output word
FW flag word
EWA 4NEB 812 6115-02b
Table 8-5. Overview of Counter Operations
Set Counter
The counter is set on the leading edge of the RLO.
Reset Counter
The counter is set to zero as long as the RLO is "1".
Count Up
The count is incremented by 1 on the leading edge of the RLO.
When the RLO is "0", the count is not affected.
Count Down
The count is decremented by 1 on the leading edge of the RLO.
When the RLO is "0", the count is not affected.
Parameter S5-90U
0 to 31
The data for these words must
be in BCD code.
STEP 5 Operations
Meaning
S5-95U
0 to 127
8-25