GE 745-W3-P5-G5-HI-ALR On site interface module
When the system starts running, 745-W3-P5-G5-HI-ALR calls the subroutine HSC-INIT with the purpose of initializing HSC0, setting its control byte SMB37 data to 16 # F8, writing the current and preset values to the high-speed counter, and connecting interrupt event 12 (i.e. the current value of the high-speed counter is equal to the preset value interrupt) to the interrupt service program COUNT-EQ through the interrupt connection instruction ATCH, and executing the ENI instruction. 745-W3-P5-G5-HI-ALR globally interrupts.
When the current value of the high-speed counter is equal to the preset value, 745-W3-P5-G5-HI-ALR executes the interrupt service program, clears the value of SMD42, and executes the HSC command again to rewrite the current value and preset value of the high-speed counter. 745-W3-P5-G5-HI-ALR simultaneously sets M0.0, and the motor stops running.
Accurate positioning of three-phase AC asynchronous motor controlled by high-speed counter instructions and rotary encoder of PLC
1.1 System working principle
The combination of high-speed counter instructions and encoders in PLC can achieve precise positioning and length measurement in modern industrial production automatic control. At present, most PLCs have high-speed counter function, for example, Siemens S7-200 series CPU226 PLC has 6 high-speed counters. A high-speed counter can accurately count high-speed pulses with a pulse width smaller than the scanning cycle of the PLC host, and can process pulse signals with frequencies up to tens or hundreds of kHz without the need for special functional units. The rotary encoder can convert the angular displacement on the motor shaft into a pulse value.
The accurate positioning control system is achieved by using the high-speed counter instructions and encoder of PLC to control the three-phase AC asynchronous motor. The principle is to convert the motor angular displacement into pulse value through a photoelectric rotary encoder connected coaxially with the motor. The number of pulses emitted by the encoder is counted through the high-speed counter of PLC, thus achieving positioning control.
1.2 Design and Implementation
Take the design of positioning control for transmission belts as an example to illustrate. We now need to use a conveyor belt to transport goods, with a distance of 10 cm from the starting point to the designated location (destination). It is now required that when the goods on the conveyor belt run 10 cm, the conveyor belt motor stops running.
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