（1） TON（2） TOF （3） TONR
S7-200 series PLC timer instructions
Category: plc program
S7-200 series PLC compare instruction
SIEMENS S7-200 programming software in the STEP-7, a special compare instruction: IN1 and IN2 to compare the two data types can be B, I (W), D, R, that is, byte, word, integer, double word integers and real numbers; you can also have other comparative:>, <, ≥, ≤, , and so on. When the comparison … Continue reading S7-200 series PLC compare instruction
Siemens S7-200 series PLC LAD STL instruction Ladder Diagram
Gray Code Converion in Ladder Logic
Gray Code Converion in Ladder Logic
two timers ladder logic program
There are two timers here, T4:0 and T4:3 each have a name given to them by the programmer
Example of a simple ladder logic program
The Way of PLC memory Access to data
1. Bit, byte, Word and double word1-bit binary number (bit) value of 0 and 12 different, can be used to switch (or digital) of two different States, such as the contacts open and close coils powerup and powerdown. If the bit is 1, it means that the ladder diagram programming elements in coils "electricity", normally … Continue reading The Way of PLC memory Access to data
PLC Siemens series power requirements and calculations
S7-200 CPU module 5VDC 24VDC power supply:CPU when there are extension modules via the I/O bus to provide 5V power supply, 5V power consumption of all the extension modules and cannot exceed the power rating of the CPU to provide. If an external 5V power supply won't be enough. Each CPU has a 24VDC sensor … Continue reading PLC Siemens series power requirements and calculations
PLC Siemens series analog input (A1)
S7-200 analog values (such as temperature or voltage) into 1 Word (16-bit) number. Zone identifier (AI), the length of the data 
and the bytes of the start address to access these values. Because analog input for 1 Word, and an even number of bytes (for example, 0, 2, 4), must be even-numbered byte … Continue reading PLC Siemens series analog input (A1)
Siemens S200 PLC stores local variables (L)
Local variable storage variable storage is very similar, the main difference is that the local variable storage is partially valid, variable storage is global. Global refers to the same memory can be any program (such as the main program, interrupted procedures or subroutines) access, partially valid is stored and associated with specific programs. Local … Continue reading Siemens S200 PLC stores local variables (L)
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