Siemens Simatic S7-200 System Manual page 73

Network 1
"Start_1"
"Pump_1"
Network 2
"Start_2"
"Pump_2"
Network 3
"High_Level"
Network 4
"Hi_Lev_Reached"
Network 5
"Mix_Timer"
Network 6
"Mix_Timer"
Network 7
"Low_Level"
"Reset"
Network 8
"Low_Level"
Network 9
Figure 4-3
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02
Fill the tank with Ingredient 1.
"Stop_1" "High_Level"
Fill the tank with Ingredient 2.
"Stop_2" "High_Level"
Set memory bit if high level is reached.
Start timer if high level is reached.
Turn on the mixer motor.
"Hi_Lev_Reached"
Drain the mixing tank.
"Low_Level"
Count each cycle.
"Mix_Timer"
Reset memory bit if low level or time-out.
"Mix_Timer"
End the main program.
Sample Program in Ladder Logic
Getting Started with a Sample Program
"Pump_1"
"Pump_2"
"Hi_Lev_Reached"
S
1
"Mix_Timer"
IN TON
PT
+100
"Mixer_Motor"
"Steam_Valve"
"Drain_Valve"
"Drain_Pump"
"Cycle_Counter"
CU CTU
R
PV
+12
"Hi_Lev_Reached"
R
1
END
4-5