Siemens Procedure 160 for Two and Three Lift PLCs

Summary. As shown in the figure below, the comparison instructions include numerical comparison instructions and string comparison instructions. Numerical comparisons include byte comparison, int comparison, two-word comparison, and real number comparison instructions.

For you, you can find the Siemens PLC elevator comparison instruction program diagram As shown in the figure below, the comparison instruction manuscript contains numerical comparison instructions and string comparison instructions. Among them, numerical comparison includes byte comparison, int comparison, two-word comparison, and real number comparison refers to pure absolute order.

The system is mainly composed of two parts, of which the logic part of the elevator control is realized by the PLC. By analyzing and studying the actual operation and control law of the elevator, the elevator linkage control program is designed and developed, so that the PLC can control the operation of the elevator. The speed regulation part of the elevator is equipped with a high-performance vector control inverter, and a pulse generator (encoder) is used to measure the speed of the squirrel cage traction motor, so as to form a closed-loop vector control system of the motor and realize the operation of the variable voltage variable frequency (VVVF) of the motor of the squirrel cage traction motor.

The PLC first receives the call signal and the leveling signal from the elevator, and then according to the state of these input signals, through a series of complex control programs inside, the logical relationship of various signals is processed in an orderly manner, and finally the switching control signal is sent to the DC door control motor, inverter and various displays in a timely manner to control the elevator. In the elevator control system, because the control of the elevator belongs to the random control, the correlation between various input signals, between output signals and between input signals and output signals is very strong, and the logical relationship is very complicated to deal with, which brings great difficulty to the programming of PLC.

At the same time that the PLC sends a switching control signal to the inverter, in order to meet the requirements of the elevator, the inverter needs to complete the speed detection and feedback of the motor through the pulse generator and PG card coaxially connected by the squirrel cage drag motor, so as to form a closed-loop system. The pulse generator outputs the pulse, and after the PG card receives the pulse, it feeds back to the inverter for calculation and adjustment. According to the phase sequence of the pulse, the direction of rotation of the motor can be judged, and the speed of the motor can be measured according to the frequency of the pulse.

Programmable logic controller, which uses a class of programmable memory for its internal storage programs, executes user-oriented instructions such as logic operations, sequence control, timing, counting and arithmetic operations, and controls various types of machinery or production processes through digital or analog inputs and outputs.

The working principle of PLC The equivalent working circuit PLC is an electronic component with a microcomputer as the core, which can be regarded as a combination of various relays, timers, counters and statesmen. The input relay of the PLC, which is driven by an external switch through the input terminal;Output relays within the PLC with numerous internal and external output contacts. In addition, PLCs have "soft" components such as timers, counters, status registers, etc., which are equipped with actuators and many electronic normally open and normally closed points that can be freely selected for use within the PLC.

The PLC control system is mainly composed of three parts: the input part, the control part and the output part. The input part is composed of user input devices, such as pressing switches, operating switches, limit switches and sensors.

They are connected directly to the input terminals of the PLC to generate input signals either from the elevator car control board or from the elevator shaft. The control part is to compile the user program according to the actual control requirements of the controlled object, and the prepared program is sent to the user program memory in the PLC through the programmer, the CPU repeatedly scans and executes the user program, and generates various output control signals, and the control function of the PLC is realized through the user program. The output part is mainly composed of user output equipment, such as contactors, relays, etc., which are directly connected to the output terminal of the PLC to control the action of the controlled object.

How it works: The working process of PLC is essentially the process of executing the program. When the PLC is running, the CPU performs an operation per cycle according to the principle of time-sharing operation, because the operation and processing speed of the CPU is very fast, so that the results that appear externally seem to be completed at the same time from a macro point of view, and the process of time-sharing operation is called the scanning of the program by the CPU. The working process of the PLC is divided into three phases:

Input processing, program execution, and output processing. (1) Input processing PLC executes the user program in a repetitive scan manner. Before executing the program, the on-off status (input signal) of all input terminals is read into the input image register in the order of address encoding, and then the program execution begins.

During execution, even though the input state changes, the contents of the input image register remain unchanged and the input state is not reread until the input processing phase of a scan cycle. (2) Program ExecutionIn the program execution stage, PLC scans the user program sequentially. The information required for the execution of each program is read from the input image register and other software component image registers and participates in the calculation, and then the execution result is written into the relevant software component image register, so the content of each software component image register is constantly changing with the execution of the program.

3) Output processingWhen all instructions are executed, all the states in the output image register are transmitted to the output latch register, which constitutes the actual output of the PLC and is sent to the actuator by the output terminal.

Now the elevator is rarely controlled by PLC, the accuracy of PLC control is not high, he is through the acquisition of various travel limit switch signals to control the main motor and the door motor forward and reverse rotation has stopped. It's a bit of a hassle to be specific, and you can communicate privately when you have time.