PLC system parameters (core of the core):
CPU model and performance: processor speed, memory capacity (program memory, data memory), instruction execution time, number of tasks/programs supported. Determine the complexity of control logic and processing speed.
I/O capacity and type:
Digital input/output (DI/DO): number of points (such as 16, 32, 64...), voltage level (such as 24VDC, 120/230VAC), current drive/sink capability (DO), input type (source/sink PNP/NPN).
Analog input/output (AI/AO): number of points, signal type (such as 4-20mA, 0-10V, thermocouple, RTD), resolution (such as 12 bits, 16 bits), accuracy.
Special function modules: high-speed counting, pulse output, positioning control, weighing, temperature control, communication protocol gateway, etc.
Expansion capability: the maximum number of expansion racks/modules supported, the maximum number of I/O points. Determines the future scalability of the system.
Communication interface and protocol:
Built-in interface: serial port (RS232/RS485), Ethernet port (10/100/1000Mbps), USB (programming/maintenance).
Supported protocols: Profibus, Profinet, EtherNet/IP, Modbus TCP/RTU, CANopen, CC-Link, etc. Determines the interconnection and interoperability with host computers, HMI, inverters, other PLCs, instruments and other equipment.
Programming software and language: supported programming languages (Ladder Logic, ST, FBD, SFC, IL), software version compatibility, and authorization requirements.
Power system parameters:
Main power input: voltage level (such as 220VAC single-phase, 380VAC three-phase), frequency (50/60Hz), rated current/power capacity. It must meet the total power consumption of all devices in the cabinet and leave a margin.
PLC power module: input voltage range, output voltage (usually 24VDC), rated output current/power. It must meet the power supply requirements of PLC CPU and local I/O modules.
24VDC system power supply: quantity, rated output current/power. It is used to power sensors, relays, small actuators, and other low-voltage devices. Redundancy or sufficient margin is usually required.
UPS/backup power supply (optional): capacity, backup time. Ensure that key equipment continues to operate or shuts down safely during short power outages.
Cabinet physical parameters:
Dimensions (height x width x depth): Determined according to internal component layout, heat dissipation requirements, wire trough space, and future expansion space. Standard dimensions such as 800x600x200mm, 1000x800x400mm, etc. can also be customized.
IP Rating: such as IP20 (only finger-proof), IP54 (dust-proof and splash-proof), IP65 (dust-proof and spray-proof). Choose according to the installation environment (control room, workshop, outdoor).
Material: cold-rolled steel plate (commonly used, requires plastic spraying for corrosion protection), stainless steel (304/316L, used in corrosive environments such as food, chemical, outdoor, etc.).
Color: usually RAL 7035 (light gray) or customer-specified color.
Installation method: wall-mounted, floor-standing (with base), cabinet installation.
Heat dissipation parameters:
Heat dissipation method: natural ventilation (IP20/IP30 cabinet), forced ventilation (fan, filter required), air conditioning (precision air conditioning, used in high heat or high temperature environment).
Rated heat dissipation/cooling capacity: must be greater than the total heat generated by all equipment in the cabinet, and take into account the influence of ambient temperature.
Fan specifications (if applicable): quantity, voltage, air volume, noise.
Safety and protection parameters:
Main circuit breaker/disconnector: rated current, breaking capacity, number of poles.
Branch circuit breaker/fuse: protect each circuit (PLC power supply, 24VDC power supply, motor circuit, heating circuit, etc.).
Emergency stop button: safety level (such as SIL2, PLd), contact type (normally closed).
Safety relay/safety PLC module (optional): used to implement safety functions (such as safety door locks, safety light curtains).
Surge protector (SPD): used to protect power and communication lines from lightning strikes or overvoltage shocks.
Grounding: main grounding bar specifications, grounding resistance requirements (usually ≤4Ω).

Integration and modularization:
PLC, power supply, I/O modules, protection devices, terminal blocks, human-machine interface, etc. are integrated into a standard or customized cabinet.
Modular design is adopted for easy installation, maintenance, expansion and replacement.
High reliability:
Industrial-grade components are selected to meet the requirements of wide temperature range, vibration resistance and electromagnetic interference resistance.
Reasonable heat dissipation design ensures that components work at a suitable temperature.
Complete electrical protection (overcurrent, short circuit, overvoltage, undervoltage).
Clear identification and documentation reduce maintenance errors.
Redundant design (power supply, network, CPU) is optional for critical occasions.
Strong safety:
The cabinet protection level ensures the safety of personnel and equipment from environmental damage.
Built-in safety functions such as emergency stop, isolation, interlocking, etc.
Comply with relevant electrical safety standards (such as IEC 60204-1).
Good grounding and EMC design to prevent static electricity, interference and electric shock risks.
Easy maintenance:
Front door or double door design for easy operation and maintenance.
Reasonable layout of components and clear divisions (such as strong current area and weak current area).
Sufficient wiring space and cable troughs, clear cable identification.
Pull-out mounting plate or modular drawer design (large cabinet).
Equipped with programming/debugging interface (USB/Ethernet).
Flexibility and scalability:
Designed with future expansion needs in mind (reserved space, I/O margin, power margin).
Supports multiple communication protocols and is easy to integrate into different systems.
Customized design can be performed according to different process flows and equipment requirements.
Standardization and normativeness:
Follow electrical design specifications (wiring, color, identification).
Meet industry standards and customer-specific requirements.
Provide complete drawings (electrical schematics, layouts, wiring diagrams) and technical documents (BOM, operation and maintenance manuals).
Visualization and convenient operation (optional):
Integrated HMI touch screen, providing a human-machine interaction interface for monitoring, operation, parameter setting, and fault diagnosis.
Status indicator lights (power, operation, fault), buttons, selector switches, etc.

Factory automation production line: focus on logic control, sequential control, I/O points, communication networking, and reliability.
Process control (chemical, water treatment): focus on analog processing, PID control, communication protocol compatibility, explosion-proof and anti-corrosion (cabinet material/IP level), and safety.
Mechanical equipment matching: focus on compact size, cost-effectiveness, specific functions (such as motion control), and protection level.
Building automation: focus on communication protocols (BACnet, Modbus), integration with third-party systems, and energy management functions.
Test bench: focus on data acquisition speed, accuracy, flexibility, and test sequence control.