Siemens Simatic S7 Series System Manual

Program instructions
7.17 Timer
S7-200 SMART
342 System Manual, 09/2015, A5E03822230-AC
TOF Off-delay timer example
LAD
STL
10-ms timer T33 times out after 1 s
(100 x 10 ms).
• I0.0 ON-to-OFF = T33 enabled
• I0.0 OFF-to-ON=disable and reset
T33
Network 1
LD I0.0
TOF T33, +100
Timer T33 controls Q0.0 through timer
contact T33.
Network 2
LD T33
= Q0.0
Timing Diagram
Effect of timer resolution on when timer bits and current time values are updated
●
1 ms
timer: The timer bit and the current value are updated asynchronous to the scan
cycle. For scans greater than 1 ms, the timer bit and the current value are updated
multiple times throughout the scan.
●
10 ms
timer: The timer bit and the current value are updated at the beginning of each
scan cycle. The timer bit and current value remain constant throughout the scan. Time
intervals that accumulate during the scan are added to the current value at the start of
each scan.
●
100 ms
timer: The timer bit and current value are updated when the instruction is
executed; therefore, ensure that your program executes the instruction for a 100-ms timer
only once per scan cycle in order for the timer to maintain the correct timing.

Siemens Simatic S7 Series Specifications

General

CPU	Varies by model (e.g., S7-300, S7-400, S7-1200, S7-1500)
Communication Interfaces	PROFIBUS, PROFINET, Ethernet, MPI
Programming	TIA Portal, STEP 7
Programming Languages	LAD, FBD, STL, SCL, GRAPH
I/O Modules	Digital, Analog, Specialty modules available
Operating Temperature	0°C to 60°C (standard models)
Mounting	DIN rail mounting
Operating Voltage	24V DC or 120/230V AC (varies by model)
Protection Class	IP20 (standard models)
Memory	Varies depending on the S7 model. Includes work memory (RAM) for program execution, load memory (EEPROM or Flash) for program storage, and system memory for operating system functions. Memory sizes range from kilobytes to megabytes.