Structure of the Siemens S7 PLC timer

S7 clock time by time and time value is composed of two parts, time is equal to the product of time and timing values. When the timer runs, the timing values continue to lose 1, until reduced to 0, down to 0 means that the time to. Time after time to cause the timer contacts.


Timer No. 0 on the 11th store timing values in BCD code format, three-bit BCD code range is 0~999. 12th, 13 storage time base in binary format.


As can be seen from the following table: small time base timer resolution high but narrow time range; base at low resolution, wide timing range.
Time base binary base resolution timing range
10 s 00 0.01 s 10ms to 9s_990ms
100ms 0l 0.1 s 100ms to 1m_39s_900ms
1 s to 10 1S 1S 16m_39s
10 s 11 10 s 10s to 2h_46m_30s


When the timer starts, the accumulator 1 lowWord content is loaded by as time timing. The process is controlled automatically by the operating system, the user simply accumulators mount a different number, you can set the time you want.
Recommend the following intuitive syntax:
L W#16# txyz
Where: t,x,y,z is a decimal number;
T = time base, values of 0,1,2,3 to represent the time base for 10ms, 100ms, 1s, 10s.
XYZ= timing values, value range: 1 to 999.
Can also be used directly in S5, mounted timing values time notation, for example:
L S5T# aH_bbM_ccS_dddMS
Where: a= hours, BB= minutes, CC= seconds, DDD= milliseconds.
Range: 1MS to 2H_46M_30S; at this point, the time base is automatically selected, the principle is: according to the scheduled time can meet the requirements of timing range minimum time base.
S7-300 offers a variety of forms of timer: pulse timer (SP), extended timer (SE), ondelay timer (SD), connected with keep delay timer (SS) and power off delay timer (SF).