Basic Framework and Core Positioning
The official system manual for Siemens SIMATIC S7-1500 automation system and ET 200MP distributed I/O system was released in December 2014 (document number A5E03461182-AC), aiming to provide technical guidance for industrial automation engineers throughout the entire process from project planning to equipment maintenance, suitable for scenarios such as machine manufacturing and process control. The document follows a "general sub general" structure, first outlining the system positioning and components, then explaining the implementation details in modules, and finally supplementing technical parameters and appendices to ensure the coherence and operability of information.
System Overview and Core Components
1. S7-1500 automation system
Positioning and advantages: As an upgraded product of S7-300/400, it focuses on high cost-effectiveness and compact design, supports up to 32 modules (slots 0-31), integrates high-speed backplane bus (improves data transmission efficiency), web server (remote monitoring) and Motion Control function (drive control), meets IP20 protection level, and needs to be installed in the control cabinet.
Core components:
Example of Key Parameters for Component Type Function Description
The CPU executes user programs and provides PROFINET/PROFIBUS communication interface model 1518-4PN/DP, supporting 8 communication modules
The system power supply (PS) is powered by the backplane bus, and the diagnostic function integrates PS 25W 24V DC and PS 60W 120/230V AC/DC
I/O module for digital/analog signal acquisition and output, including technical modules (counting, positioning), digital module DI 32x24VDC HF, analog module AI 8xU/I
Communication module (CM) extends communication interface, supporting point-to-point (RS232/RS485), PROFINET/Ethernet CM 1542-5 (DP master/slave)
2. ET 200MP distributed I/O system
Positioning and advantages: A scalable distributed I/O solution that communicates with the central controller through PROFINET/PROFIBUS, supports high channel density (25mm wide module with 32 channels), adapts to S7-1500 I/O modules, and can be flexibly expanded to 30 I/O modules (PN interface) or 12 I/O modules (DP interface).
Core components:
Example of Key Parameters for Component Type Function Description
The interface module (IM) connects distributed I/O with the central controller, and supports isochronous mode (250 μ s cycle) for PROFINET version (IM 155-5 PN ST/HF) or PROFIBUS version (IM 155-5 DP ST) IM 155-5 PN HF
The I/O module is compatible with S7-1500 and supports digital, analog, and technical modules with the same parameters as S7-1500 I/O module
The system power supply (PS) is powered by the backplane bus and needs to be separately configured with the same S7-1500 system power supply

Application planning and hardware configuration
1. Hardware configuration rules
S7-1500 configuration restrictions:
Module type allows maximum number of slots. Please note
Load power (PM) slot 0 has no limit (only 1 is displayed in STEP 7) and does not occupy the backplane bus. External wiring is required
System power (PS) slots 0, 2-31, 3 for supplementing backplane bus power
CPU slot 1: 1 required component, indispensable
I/O modules 2-31, 30 including digital, analog, and technical modules
Communication module 2-31 4-8 (depending on CPU model) CPU 1511-1PN supports 4, 1518-4PN/DP supports 8
ET 200MP configuration limit:
Interface type allows maximum number of I/O modules in the slot. Remarks
PROFINET (IM 155-5 PN) slot 1 30 (slots 2-31) supports system power expansion (up to 3)
PROFIBUS (IM 155-5 DP) slots 2 12 (slots 3-14) without system power expansion function
2. Power configuration and power balance
Classification of power supply types:
System power supply (PS): only supplies power to the backplane bus (module electronic components, LEDs), needs to be connected to the backplane through a U connector, supports 24/48/60V DC or 120/230V AC input;
Load Power Supply (PM): Provides power to I/O module input/output circuits, sensors/actuators, without backplane bus connection, installed on rails but not occupying slots, recommended Siemens SIMATIC series (PM 70W/190W 120/230V AC).
Power balance calculation: It is necessary to ensure that the backplane bus "supply power ≥ consumption power", and STEP 7 will automatically verify. If the power is insufficient, the system power supply needs to be added. The calculation logic is as follows:
Calculate the backplane power supply of CPU/interface modules (such as 14W provided by CPU 1516-3 PN/DP);
Accumulate the power consumption of each I/O module (such as DI 32x24VDC HF consumption of 1.1W);
If the total consumption exceeds the supply, a system power supply (such as PS 25W to supplement 25W) needs to be added to slot 2-31.
Installation and wiring specifications
1. Installation process and requirements
Guide rail installation: Use TH 35 standard guide rails (length 160/245/482.6/530/830/2000mm), with M6 fixing screws (torque 4Nm). For guide rails ≥ 530mm, fixing screws should be added every 500mm;
Module installation sequence: From left to right, it is "System power supply (optional) → CPU/interface module → I/O module". The modules are mechanically and electrically connected through U connectors, and the last module does not require the installation of U connectors;
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