Siemens SIMATIC S5-90U System Manual page 484

Function Modules
Addressing
A counter module can be addressed like a two-channel digital module (channel "0" or "1"). For
enabling and resetting the counter, you address the module like a digital output module.The counter
reading is scanned in the same way as a digital input module.
Counter enable
(Set to start value)
Counter reset
Scan
"1" = Counter at zero
Figure 16-6. Scanning the Counter Module (500 Hz)
Timing Diagram
S Q x.0
1
0
1
0
6
0
1
0
Figure 16-7. Timing Diagram: Setting and Resetting an Output of the
16-16
S Q x . 0
S Q x . 1
R Q x . 0
R Q x . 1
A I x . 0
A I x . 1
Channel number
Slot address
Counter Module (500 Hz)
Channel "0"
Channel "1"
R Q x.0
Enable
Counting
pulses
Output Q
Time
EWA 4NEB 812 6115-02b
S5-90U/S5-95U