PLC programming for small knowledge and interpretation - convenient operation

Siemens PLC controller according to control the size of the classification can be divided into large and medium-sized machine and small.

minicomputer: minicomputer control points, generally within a 256 - point, suitable for single or small system control.

Siemens S7 - minicomputer 200: processing speed 0. 8 to 1. 2女士; Memory 2 k; Digital quantity 248 points; Analog 35 road. Medium-sized machine:

medium machine control points is generally not more than 2048 points, of equipment can be used to control directly, can also for multiple monitor to the next level of programmable controller, it is suitable for medium or large control system.

Siemens S7 - medium-sized machine 300: processing speed 0. 8 to 1. 2女士; Memory 2 k; Digital quantity 1024 points; Analog 128 road; PROFIBUS network; Industrial Ethernet; MPI。

mainframe, the mainframe control points generally greater than 2048 points, can not only for more complex arithmetic. Mode

control system set up a remote/local/manual button:

remote: only through a PC to control the automatic start/stop system, local control priority, single device in SPC, can through the upper machine equipment for soft hand/automatic switch, soft hand start/stop.

local: only through touch screen to control the automatic start/stop system, local control priority, single device in SPC, can through the touch screen to soft hand/automatic switching device, soft hand start/stop.

manual: manual control, PC/touch screen failure, only by manual control start/stop of the equipment.

single equipment control single device must have a soft hand/automatic switch and soft hand when can start/stop function, the automatic switch to the soft hand, equipment can't stop; By the soft hands rash to the automatic exchange equipment start/stop depends on the automatic program.

single device ( Pump, fan and other large equipment) Run 24 hours, it must rotate and must have a cumulative operation time, if by the upper machine set except the start/stop order, the operator set.

program structure unified

OB1: main program

OB100: initialization program ( Without the main program calls)

OB35:100ms ( Can be modified) Interrupts ( Without the main program calls) , you can call the PID module;

OB80, OB82, OB85, OB86, OB87, OB121, OB122: fault diagnosis module ( Without the main program calls, no programming)

FC1: system mode FC2: input processing

FC3: output processing FC4: run processing

FC5: stop processing FC6: hand switch

FC100: used to create some can be recycled after calling subroutine

FC105: systems, analog input subroutine ( Can be circular calls)

FC106: systems, analog output subroutine ( Can be circular calls)

modbus communication ( CP341) : FB7: P_RCV_RK FB8: P_SND_RK CP340:

communication FB2: P_RCV, FB3: P_SND

general PID: use FB41

temperature and humidity PID: using FB58

if the program block and the system block repeat, please give way.

block DB1: AI data, type, REAL, and PC interface

DB2: AO data, type, REAL, and PC interface

DB3: DI data types: BOOL, and PC interface

DB3: DO data types: BOOL, and PC interface

DB5: accumulated, equipment running time and traffic types: REAL, with PC interface;

DB6: alarm message types: BOOL, and PC interface

DB7: type: REAL, middle register

DB8: types: INT, middle register

DB9: type: WORD, middle register

DB10: types: BOOL, middle register

DB11: after used and communications equipment, such as: the MODBUS communication such as

DB100: after used for call FB block background data block area

M: as intermediate variable

DP DP slave station fault diagnosis must be from the station fault diagnosis, fault alarm, with FB125 can.

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