Siemens SIMATIC S7-300 Reference Manual page 4

Overview of the comparison list
• Measuring runtime of instructions and program parts (see below)
• Loading objects to the CPU: which changes and which changed blocks you can load to the CPU in which
operating mode. (next page)
• Overview, requirements, framework conditions and legends to the comparison list (page 7)
• Comparison list for S7-300, S7-400, S7-1200, S7-1500 including CPU 150xS software controller:
Which instructions and functions can be used for which controller family. (from page 8)
Annex: Optional instructions for SIMATIC Ident
•
Measuring runtime of instructions and program parts
The runtime of parts of the user program and instructions depend on numerous factors. A tabular list is therefore not possible.
The RUNTIME (runtime measurement) instruction is used to measure the runtime of the entire program, individual blocks or
command sequences. The runtime measurement starts with the first call of the RUNTIME instruction and ends with the
second call.
For the runtime measurement of individual instructions, you use an OB priority >15. As a result, "Monitor online" does not
falsify the runtime. You can find additional information in the SIMATIC STEP 7 online help. Enter "Runtime" in the search box.
Program example in SCL:
"Common_Data".opt.Last_Cycle := RUNTIME(#Tag_Memory); //Start of runtime measurement, LReal
"speed test FB opt_DB"(ON_2:="i1",...);//Runtime measurement through RUNTIME
"Common_Data".opt.Last_Cycle := RUNTIME(#Tag_Memory); //End of runtime measurement
The Last_Cycle tag contains the time that has elapsed between the previous call and the current call of RUNTIME.
A5E33285102-AB Page 3