1 Introduction This paper takes the robot control in a certain logistics control as an example, analyzes the control method of the PLC and the stepping drive, and the main hardware involved in the system is S7-200PLC and SH-2H057 stepped drives. (1) The S7-200PLC series is a programmable controller of Siemens, which meets a variety of automation control requirements, because there is a compact design, good scalability, low price and powerful instructions, S7-200. S7-200PLC can meet small-scale control requirements. In addition, rich CPU type and voltage level make it very powerful when solving the user's industrial automation problem. The CPU is responsible for executing procedures and storage data to control industrial automation control tasks or processes; input and output are control points of the system: the input section collects signals from field devices, and the output part controls pump, motor, and control. Other equipment; power supply provides power to any device connected to the CPU; the communication port allows the S7-200CPU to connect to the programmer or some other devices; the status signal light shows the working mode of the CPU (running or stop), this machine The current state of I / O, and the system error checking; its communication performance can be provided by the expansion module; the number of I / O points (CPU 221 does not extend) can be increased by extending modules; some CPUs have built-in real-time clocks, or add Real time clock card; LeePROM card can store the CPU program, or you can send a program in a CPU to another CPU; extending the data storage time in the RAM by an optional plug-in battery cartridge; maximum I / O configuration. (2) The SH-2H057 driver input signal has three ways, they are: step-in pulse signal CP, directional level signal DIR, off-plane signal free. The internal signals are directly connected to optocoupler through 270 Ω current limiting resistance. The negative input, and the circuit form is exactly the same, the three-channel optical coupling positive input terminal is an OPTO end, and the three input signal is connected to a common eolar mode in the drive, so the OPTO side needs to connect the VCC terminal of the external system. If VCC is + 5 volts, can be accessed directly; otherwise, additional limiting resistors need to be additionally added to the driver to provide 8-15 mA drive current. The step pulse signal CP step pulse signal CP is used to control the position and speed of the stepper motor, that is, the drive drives the step motor to rotate a step angle, and the frequency change of the CP pulse is simultaneously step. The rate of input the motor changes, controls the number of CP pulses, the stepper motor can be accurately positioned. This makes it easy to achieve the purpose of stepper motor speed and positioning. The CP signal of this drive is effective, requiring the CP signal to be 8-15 mA, and there is a certain requirement for the CP pulse width, generally not less than 5 μs. The directional level signal DIR direction level signal DIR is used to control the direction of rotation of the stepper motor. When this is high, the motor is a steering; the secondary end is low, and the motor is another steering. The motor reversal must be performed after the motor is stopped, and the commutation signal must be sent before the final CP pulse in the previous direction and the first CP pulse in the next direction. Off-plane signal Free When the drive is powered on, the stepper motor is in a locked state (when the CP pulse is not applied) or the operating state (applied CP pulse), but the user wants to manually adjust the motor without closing the drive power supply, then you can use To this signal, this signal is effective, and the motor is in a free torque state; when this signal is high or suspended, the offline is canceled. Introduction to Stepping Motors For the SH-2H057 drive for driving the second phase or four-phase hybrid stepping motor (also known as induction sub-formula), which is typically driven by the motor following the motor. The outline of the motor is different, and the connection to the drive is also different. The motor used in this system is a two-phase four-wire motor, which can be directly connected to the drive. See the schematic of the robot motor drive module of Figure 1. 2 System Working Project The robot portion of the system is composed of chassis, vertical rod, arm, hand, where the chassis is driven by a stepping motor, can rotate in reverse time; rod is driven by a stepper motor, can be moved up and down; A stepper motor drives, can telescope before and after, hand controlled by air pump, can be searned and relaxed. There is a position detection signal in the respective position for positioning. See Figure 1. (1) The shipping process is started from the reset position. According to the request to the corresponding shipment counter (1, 2, 3), the chassis is rotated to the required position, the column decreases, the arm extends, and positions the latter hand. The column rises while recovering the arm (so as not to run in the operation with other equipment), then go to the corresponding shipperary counter (left, or right outgoing table), the column decrease, the arm extends, hand open, put the goods in the corresponding shipping Table. (2) The purchase process is started from the reset position. According to the request to the corresponding shipping station (left, or right outgoing table), the chassis is rotated to the required position, the column decreases, the arm extends, positions the post, the column rise At the same time, the arm recycling (so as not to run with other equipment), then go to the corresponding shipping table (1, 2, 3), the column decrease, the arm extends, the hand is opened, put the goods in the corresponding shipping station superior. 3 System Design Thought Step Control Circuit Design Thought, PLC Relay Output Module is low, so high-frequency pulse square wave generator, gives a step-income pulse, whose oscillation frequency is set to step by step, step amount The control is detected, and the feed motor is cut off according to the output point of the position detection signal, and the step of the step motor is realized, and the program flow chart is shown in FIG. During the operation of the entire robot, the limit switch and panel operation switch and system logic switch are used as input point control engineering. The chassis in the entire system has 5 limit switches, which are positioned in 5 locations, respectively, CONTROLENGINEERINGCHINA. All rights reserved, the column has four limit switches, which are 1 reset switch, one bit limit input, upper limit, lower limit. The arm has three limit switches: the arm reset limit number, the front limit of the arm, the arm is lost. Stratger limit switch, reset the input point for the grip. A total of 13 limit switches complete all control inputs. The distribution of each limit switch is shown in Figure 1www.cechina.cn, since all through the control step motor drive module is driven by the control step motor. Here, the principle of stepping motor driver in accordance with integrated pulse output is described here. Q0.0 and q0.1 of S7-200PLC (CPU226) respectively, the motor, the motor, the front / post, the motor transmission pulse; Q0.2 of the CPU 226 pair the turntable step motor. The positive / reversal of the stepper motor is the CPU226 Q0.4 and Q0.5 respectively, and the motor, the front / post motor, the front / post into the motor; the Q0.6 and Q0.7 of the CPU 226 respectively The turntable stepper motor is correct, and the air pump switch is controlled. The design of the robot PLC program is written in the form of Data Sheet (STL) of STEP7-Micro / Win32 software. The program is easy to design and modify, the design is complete, and there is no problem to connect the stepper motor. The host machine monitoring software adopts Beijing Asian-controlled configured king software, and implements a dynamic connection of the modulus of the configuration software through the variable map to the dynamic connection of the registers of the PLC, thereby realizing monitoring of PLCs. 4 Conclusion The mechanical control system is compact, reliable action, easy to use. Responsible Editor: YYX
Our other product:
