S7-200 PLC Data area

A) digital input and output image area


1. Enter mapping registers (digital input image areas) (I)


Digital input image is S7-200CPU for the input signal state opened up a store. Register identifier for the input image I, at the beginning of each scan cycle, CPU to sample the input points and registers the sample values in the input image.


Enter image register is the digital signals of PLC receives external input window.


Can be bit, byte, Word, double word four ways to access.


(1) press the bits: from I0.0~I15.7, a total of 128 points


(2) press the bytes: from IB0~IB15, a total of 16 bytes


(3) press character: from IW0~IW14, a total of 8 characters


(4) press the double-word: from ID0~ID12, a total of 4 double word


2. The output image register (Q)


Digital output image area is the S7-200CPU for the signal at the output state of a storage area. Register the output image‘s identifier is Q (from Q0.0~Q15.7, a total of 128 points), at the end of each scan cycle, CPU registers of the output image data to output module, which then drive the external load.


Can be bit, byte, Word, double word four ways to access.


(1) press the bits: from Q0.0~I15.7, a total of 128 points


(2) press the bytes: from QB0~QB15, a total of 16 bytes


(3) press character: from QW0~QW14, a total of 8 characters


(4) press the double-word: from QD0~QD12, a total of 4 double word


Note: practically no use of input and output image area of the storage unit can be used as relay.


(B) analog input images and output image area


1. Analog input image areas (AI)


Analog input image area is the S7-200CPU analog input signal opens a store. S7-200 measurement of analog (such as temperature and pressure) into a 1length (2 bytes) of digital, analog input registers with the image identifier (AI), the length of the data (w) and the bytes of the start address.


From AIW0~AIW30, a total of 16 characters, a total of 16 analog input is allowed.


Description: analog input values for readonly data.


2. Analog output image area (AQ)


Analog output image area is the S7-200CPU analog output signal to open a store. S7-200 1Word (2 byte, 16-bit) converts the digital proportional current or voltage. Analog output registers with the image identifier (AQ), the length of the data (w) and the bytes of the start address.


From AQW0~AQW30, a total of 16 characters, allowed a total of 16 analog outputs.


(C) the memory variable (v) (the equivalent of auxiliary relays)


PLC program execution process, there will be some intermediate results of the control process, these intermediate also need memory to save the data. Variable storage is designed according to the actual requirements. Variable storage is one of the S7-200CPU set up to save the intermediate variable data stores, represented by v.


Can be bit, byte, Word, double word four ways to access.


(1) press the bits: from V0.0~I5119.7, a total of 40,960 points. CPU221, CPU222, memory only 2048 bytes of the variable, its variable store only to V2047.7.


(2) press the bytes: from VB0~VB5119, a total of 5,120 bytes


(3) press character: from VW0~VW5118, a total of 2,560 words


(4) press the double-word: from VD0~VD5116, a total of 1280 double word


(D) information technology(m)


PLC program execution process, some flags may be used, which also use memory to storage. Memory is designed according to the requirements. Memory is one of the S7-200CPU set up to keep flag data store represented by m. Although the area is called memory, but the data can not only be, but also can be a byte, Word or double word.


(1) press the bits: from M0.0~M31.7, a total of 256 points.


(2) press the bytes: from MB0~MB31, a total of 32 bytes


(3) press character: from MW0~MW30, a total of 16 characters


(4) press the double-word: from MD0~MD28, a total of 8 double word


(E) the control relays in the order (s)


PLC program execution process, the sequence may be used. Sequence control relays are designed according to the characteristics of sequential control and. Control relay is S7-200CPU in order to control relays in the order established a store of data, denoted by s. Control process in order for the organization step process control.


Can be bit, byte, Word, double word four ways to access.


(1) press the bits: from S0.0~S31.7, a total of 256 points.


(2) press the bytes: from SB0~SB31, a total of 32 bytes


(3) press character: from SW0~SW30, a total of 16 characters


(4) press the double-word: from SD0~SD28, a total of 8 double word


(F) local storage area (l) (the equivalent of auxiliary relays)


S7-200PLC 64 bytes of local storage, which can be used as a temporary store for the 60 and passing parameters to the subroutine.


Local and variable storage is very similar, the main difference is that the variable memory is of global and local storage is partially valid. Global refers to the same memory can be accessed by any program (for example, the main program, subroutine, or interrupt). Local guide memory areas associated with specific programs.


Several programs between visits.


Local storage area is a store set up S7-200CPU as a local variable data, represented by l. Data in the region can be bit, byte, Word, double word four ways to access.


(1) press the bits: from L0.0~L63.7, a total of 512 points.


(2) press the bytes: from LB0~LB63, a total of 64 bytes


(3) press character: from LW0~LW62, a total of 32 characters


(4) press the double-word: from LD0~LD60, a total of 16 doubleword


(G) the timer memory area (t)


PLC at work and ultimately need timing, the timer is the realization of PLC timer function of timing equipment. Timer number:


T0、T1、……、T255


S7-200 has 256 timers.


(VIII) counter memory area (c)


PLC at work sometimes requires not only time count may also be required. Counter is counting device of PLC with counting function.


Counter ID:


C0、C1、……、C255


(H) high speed counter (HSC)


Today high speed counter is used to scan faster than CPU events. S7-200 high speed counters not only count the frequency of up to 30kHz.


S7-200 high speed counter there is a 32-bit signed integer to the current value of the counter. To access high-speed counter values, you must give high speed counter address, namely, high speed counter number.


High speed counter number: HSC0, HSC1, … …, HSC5.


S7-200 6 high-speed counters. Where CPU221 and CPU222 only have 4 high-speed counters (HSC0, HSC3, HSC4, HSC5)


(I) the accumulator (AC)


Accumulators can be read/write device like a memory. For example, you can use the accumulator parameters passed to a subroutine, or return from the subroutine parameters and is used to store intermediate data are calculated.


S7-200CPU provides 4 32-bit accumulator (AC0, AC1, AC2, AC3).


Can be byte, Word or double word accumulator to access data in the data. However, as bytes when reading/writing data in the accumulator, read/write only the lowest 8 bits of the accumulator in the 32-bit data data. If it is read/write in Word forms the accumulator data can only read/write in 32-bit accumulator data the low 16 bits of data. Only take the form of double words when reading/writing data in the accumulator, can read and write all 32 bits of data at once.


Because operation of PLC function is separated from the accumulator. Not as occupied as the other memory accumulators.


(J) special storage areas (SM)


Special memory is S7-200PLC the media for passing information between the CPU and the user program. They can reflect the CPU running the various status information, users can use this information to determine the machine‘s operating status, to determine the user what to do, what not to do. These special information storage to storage. Special memory is designed according to the requirements.


1. Special storage areas


It is S7-200PLC to save its State data and established a store, SM said. Special memory data is read write, some are readonly. Special memory data can be a bit or a byte, Word or double word.


(1) press the bits: from SM0.0~SM179.7, a total of 1440 points.


(2) press the bytes: from SM0~SM179, a total of 180 bytes


(3) press character: from SMW0~SMW178, a total of 90 characters


(4) press the double-word: from SMD0~SMD176, a total of 45 double word


Description: special the first 30 bytes of the memory area is readonly.


2. Commonly used special relay and its function


Special storage for CPU and the exchange of information between users, for example, SM0.0 has been the 1 State, SM0.1 only the first scan of the execution of the userprocess cycle for the 1 State. SM0.4 and SM0.5 provide a period of 1min and 1s of the clock pulse. SM1.0, SM1.1 and SM1.2 respectively zero flag, overflow flag and negative signs.

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