Siemens Simatic S7-200 System Manual page 128

Basic Concepts for Programming an S7-200 CPU
Write the outputs
Force values are applied to the
outputs as they are written.
Execute the CPU self-test
diagnostics
Figure 6-14
Figure 6-15 shows an example of the Status Chart. For more information on how to use the
Status Chart, see Section 3.8.
Status Chart
Address
"Start_1"
"Start_2"
"Stop_1"
"Stop_2"
"High_Level"
"Low_Level"
"Reset"
"Pump_1"
"Pump_2"
"Mixer_Motor"
"Steam_Valve"
"Drain_Valve"
"Drain_Pump"
"Hi_Lev_Reached"
"Mix_Timer"
"Cycle_Counter"
Figure 6-15
6-18
One Scan Cycle
Process any communication requests
Force applied to all read/write communication accesses.
Scan Cycle of the S7-200 CPU
Format
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Signed
Signed
Forcing Variables with the Status Chart
Read the inputs
Force values are applied to the inputs
as they are read.
Execute the program
Force values are applied to all
immediate I/O accesses.
Force values are applied for up to
16 memory values after the
program has been executed.
Current Value Change Value
2#0
2#0 1
2#0
2#0
2#0
2#0
2#0
2#0
2#0
2#0
2#0
2#0
2#0
2#0
+0
+0
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02