PLCThe localI/OModules are directly connected to on-site equipment in traditional industrial automation systems (sensor, Actuator) Core hardware components connected, Responsible for real-time collection of input signals (Like switch status, Temperature value) And output control instructions (Like starting the motor, Open the valve) . From the definition below, function, Detailed analysis of structure and application scenarios:
one, localI/ODefinition of modules
localI/OThe module is a programmable logic controller (PLC) The physical interface unit, Directly installed onPLCOn a rack or remote rack expanded through a bus, Through hard wiring (Cable) Connect on-site equipment, realization:
input (Input) : Receive sensor signals (Like photoelectric switch, Pressure transmitter) .
output (Output) : Drive actuator action (Like a relay, Motor starter) .
two, localI/OCore components of the module
1. Digital quantity module (DI/DO)
Digital input (DI) : Receive switch signal (0/1) , Like a button, Limit switch.
Digital output (DO) : Output switch control signal, If the indicator light is turned on, Control solenoid valve.
2. Analog module (AI/AO)
Analog input (AI) : Collect continuous signals (4-20mA, 0-10V) , Like temperature, Pressure sensor.
Analog output (AO) : Output continuous control signal, Adjusting the speed of the frequency converter, Valve opening degree.
3. Special function module
High-speed counter (HSC) : Processing encoder pulse signals (Measurement of motor speed) .
Thermal resistance (RTD) /Thermocouple module: Directly connect temperature sensor.
communication module : supportProfibus, EtherCATWaiting for the agreement, Used for distributed applicationsI/Oextend.
three, localI/OCore features of the module
1. High real-time performance
Local processing latency is typically in the millisecond range, Meet the requirements of high-speed control (Like stamping machine tools, Packaging Machinery) .
2. Strong reliability
Not dependent on the network, Strong anti-interference ability (By shielding the cable, Isolation circuit design) , Suitable for harsh industrial environments.
3. Deterministic control
PLCThe scanning cycle is strictly fixed, Ensure precise timing of logical execution (Like synchronous control of assembly line) .
4. physical connection
Hardwired to on-site equipment through terminal blocks or connectors, Reduce signal transmission risks.
four, Typical application scenarios
1. High real-time control
Example: Mold opening and closing control of injection molding machine, Require millisecond level response, localI/OThe module is directly connected to the limit switch and hydraulic valve.
Safety critical systems
Example: Emergency stop (E-Stop) Circuit through localDIThe module directly triggers the safety relay, Avoiding the risk of network latency.
2. Distributed Expansion
Example: In the automobile production line, mainPLCThrough fieldbus (asProfinet) Connect remotelyI/Oframe, Distributed Control Welding Robot, Conveyor belt.
3. Adaptation to harsh environments
Example: In mining equipment, localI/OThe module is dustproof, waterproof (IP67Grade) characteristic, Directly connect vibration sensor and pump valve.
