Detailed Explanation of EM 235 Analog I/O Module
- Model Code Breakdown
| ส่วนโมเดล | คำอธิบาย |
| 6ES7 | Prefix for Siemens SIMATIC automation product ชุด |
| 235 | Module type identifier: EM 235 analog input/output module |
| 0KD | Specification code: 4 analog inputs (AI), 1 เอาท์พุทแบบอะนาล็อก (ถึง), ±10V DC signal range |
| 22 | Hardware version number |
| 0XA0 | Standard version identifier (0XA8 is the China region version EM 235 CN) |
- ข้อมูลจำเพาะทางเทคนิคหลัก
การวางตำแหน่งผลิตภัณฑ์: Expansion module for SIMATIC S7-200 series, only compatible with S7-22X CPUs (not compatible with S7-21X), spare part
การกำหนดค่า I/O: 4 analog inputs (AI) + 1 เอาท์พุทแบบอะนาล็อก (ถึง)
Input Characteristics:
Signal type: Differential input, ±10V DC (other ranges selectable via DIP switches)
ปณิธาน: 12 bits (including sign bit)
Input impedance: ≥10MΩ (voltage input)
การป้องกันแรงดันไฟฟ้าเกิน: Up to 30V DC
Output Characteristics:
Signal type: ±10V DC (แรงดันไฟฟ้า) / 0–20mA (ปัจจุบัน, ไม่จำเป็น)
ปณิธาน: 12 bits for voltage output, 11 bits for current output
Output impedance: ≤0.5Ω (voltage output)
Load capacity: Max 5mA for voltage output, max 20mA for current output
Power Requirements:
External supply: 24ในดีซี, max 60mA
Backplane bus: 5ในดีซี, max 30mA
Power dissipation: Typical 2W
Conversion Performance:
Input conversion time: <250μs per channel
Output response time: 1.5ms to 95% steady-state value
- สภาพแวดล้อมการทำงาน
- อุณหภูมิในการทำงาน: 0–60°C (horizontal mounting), 0–40°C (vertical mounting)
- อุณหภูมิในการจัดเก็บ: -40–+85°C
- Relative humidity: 5–95% (ไม่ควบแน่น)
- Protection class: IP20 (สอดคล้องกับ IEC 61131-2)
- การติดตั้ง: การติดตั้งราง DIN (compliant with EN 50022)
- Application scenarios:
Analog signal acquisition and control for small automation systems
Monitoring and regulation of process variables such as temperature, ความดัน, and flow
Simple control loops requiring simultaneous analog input and output
- การทดแทน & รุ่นที่ใช้ร่วมกันได้
| แบบอย่าง | ความเข้ากันได้ | หมายเหตุ |
| 6ES7 235-0KD22-0XA8 | เข้ากันได้อย่างสมบูรณ์ | China version (EM 235 CN), same functions and parameters |
| 6ES7 231-0HC22-0XA0 | Input replacement | EM 231 4-channel analog input module (ไม่มีเอาต์พุต) |
| 6ES7 232-0HD22-0XA0 | Output replacement | EM 232 2-channel analog output module (no input) |
| S7-200 SMART EM AE04 | Upgrade replacement | For S7-200 SMART CPU, 4 analog inputs; similar functions but not compatible with S7-22X |
- ข้อมูลการสั่งซื้ออย่างเป็นทางการ
Standard order number: 6ES7 235-0KD22-0XA0 (global version)
China order number: 6ES7 235-0KD22-0XA8 (EM 235 CN)
Product status: Currently a spare part for S7-200 system maintenance and replacement
- Key Usage Notes
- DIP switch settings: DIP switches on the side select input signal range; only one range can be set for the entire module
- Programming:
Use Scale_I_to_R and Scale_R_to_I instructions in S7-200 software for analog/digital conversion
Analog input addresses: AIW0–AIW6 (2 bytes per channel)
Analog output address: AQW0 (2 bytes)
- Wiring rules:
Use shielded twisted-pair cable for analog signals, keep at least 10cm away from power cables
Unused channels should be shorted to avoid interference
- ข้อควรระวัง:
Both external 24V DC and backplane 5V DC power must be connected
Hot swapping not supported; install/remove only with power off
- Comparison with S7-200 SMART Modules
| รายการ | 6ES7 235-0KD22-0XA0 | S7-200 SMART EM AE04 |
| Compatible CPU | S7-22X series | S7-200 SMART series |
| ฉัน/โอ | 4AI/1AO | 4AI |
| Signal range | ±10V / 0–20mA | Multiple options (including thermocouple/RTD) |
| การสื่อสาร | PPI protocol | โปรฟิเน็ต / Ethernet |
| แหล่งจ่ายไฟ | External 24V + backplane 5V | External 24V only |
Complete Model List of Siemens EM 235 Analog I/O Modules
- Core EM 235 ซีรี่ส์โมเดล (by hardware version)
| แบบอย่าง | HW Version | Region | คำอธิบาย | สถานะ |
| 6ES7 235-0KD00-0XA0 | 0 | Global | EM 235 analog combo module, 3AI/1AO, 12-bit | ยกเลิก, early version |
| 6ES7 235-0KD10-0XA0 | 10 | Global | EM 235 analog combo module, 4AI/1AO, 12-bit | ยกเลิก, transitional |
| 6ES7 235-0KD20-0XA0 | 20 | Global | EM 235 analog combo module, 4AI/1AO, 12-bit | ยกเลิก, legacy |
| 6ES7 235-0KD22-0XA0 | 22 | Global | EM 235 analog combo module, 4AI/1AO, 12-bit, S7-22X only | Spare, available |
| 6ES7 235-0KD22-0XA8 | 22 | CN (จีน) | EM 235 CN analog combo module, 4AI/1AO, 12-bit, S7-22X only | Spare, China-only |
- Detailed Model Differences
2.1 Common Features of All EM 235 Models
ฉัน/โอ: 4AI + 1ถึง (3AI + 1AO for 00 รุ่น)
Input: ±10V DC (other ranges via DIP switches: 0–20mA, 4–20mA, mV)
เอาท์พุต: ±10V / 0–20mA (4–20mA via wiring)
ปณิธาน: 12-bit input (with sign), 12-bit voltage output, 11-bit current output
ความเข้ากันได้: Only for S7-22X CPUs (not S7-21X)
2.2 ความแตกต่างที่สำคัญ
| รายการ | 6ES7 235-0KD00-0XA0 | 6ES7 235-0KD22-0XA0/0XA8 |
| อินพุตแบบอะนาล็อก | 3 ช่อง | 4 ช่อง |
| DIP switches | Basic settings | Enhanced, supports more ranges |
| ความแม่นยำ | Basic | Improved, better anti-interference |
| พลัง | External 24V + backplane 5V | เดียวกัน, optimized to 2W dissipation |
2.3 Global vs. จีน (CN) เวอร์ชัน
6ES7 235-0KD22-0XA0: Global version, worldwide except China
6ES7 235-0KD22-0XA8: China-specific version; same functions and parameters, different certification and distribution
- การสั่งซื้อ & การทดแทน
3.1 Current Valid Part Numbers
Global: 6ES7 235-0KD22-0XA0 (spare)
จีน: 6ES7 235-0KD22-0XA8 (EM 235 CN, spare)
3.2 Upgrade Path to S7-200 SMART
| S7-200 Module | S7-200 SMART Replacement | ความแตกต่าง |
| EM 235 (4AI/1AO) | 6ES7 288-3AM03-0AA0 (2AI/1AO) | Fewer channels, enhanced functions, PROFINET/Ethernet |
| EM 235 (4AI/1AO) | 6ES7 288-3AM06-0AA0 (4AI/2AO) | More outputs, full feature upgrade |
- Important Operational Notes
- DIP switches: Set uniform measurement range for all AI channels
- Addressing:
อินพุตแบบอะนาล็อก: AIW0–AIW6 (2 bytes each)
เอาท์พุทแบบอะนาล็อก: AQW0 (2 bytes)
- สายไฟ:
Shielded twisted-pair required; separate from power cables by ≥10cm
Short unused channels to reduce noise
- พลัง: Both 24V DC external and 5V DC backplane required; no hot-swapping
The core models of the Siemens EM 235 analog I/O module are 6ES7 235-0KD22-0XA0 (ทั่วโลก) and 6ES7 235-0KD22-0XA8 (China CN), both hardware version 22 spare parts for S7-22X CPU maintenance. Earlier versions (00/10/20) are discontinued. For system upgrades, use corresponding S7-200 SMART modules.
Siemens EM 235 (4 analog inputs + 1 เอาท์พุทแบบอะนาล็อก)
is the most widely used analog mixed module for the S7-200 micro PLC.
Its core purpose: acquire multiple analog sensor signals and output one analog for closed-loop control.
It is designed for small-to-medium equipment, standalone automation, and local control systems, not large DCS systems.
Below is a complete list of applications by industry + typical control scenarios.
- General Closed-Loop Control Applications
- Constant Pressure Control
AI: Pressure transmitter (4–20mA)
ถึง: Inverter for pump/fan (0–10V หรือ 0–20mA)
Uses: Constant pressure water supply, compressed air regulation, pipeline pressure stabilization
- Constant Temperature Control
AI: Temperature transmitter, thermocouple/RTD
ถึง: Electric control valve, heater, วาล์วขยายตัวอิเล็กทรอนิกส์
Uses: Water tank temperature control, small oven, HVAC unit, heat exchanger station
- Constant Level Control
AI: Level transmitter (hydrostatic/ultrasonic)
ถึง: Inlet control valve, variable-speed drainage pump
Uses: Water tank, reservoir, water tower, small storage tank level maintenance
- Flow & Metering Control
AI: Electromagnetic flowmeter, turbine flowmeter
ถึง: Control valve, metering pump, proportional valve
Uses: Batching systems, dosing, fluid proportioning
- Tension & Position Control
AI: Tension sensor, displacement transducer
ถึง: อินเวอร์เตอร์, proportional hydraulic valve
Uses: Constant tension in textile, การพิมพ์, ฟิล์ม, cable machinery
- Industry-Specific Applications
2.1 Water Supply & Wastewater Treatment
Small constant-pressure water supply systems
Sewage lift pumps, integrated wastewater treatment
Water tank level monitoring and auto refill
Pipeline pressure/flow monitoring and inverter control
2.2 เครื่องปรับอากาศ & Refrigeration
Chillers, air-cooled units
Fan coil units, air handling units
Heat exchanger station: primary/secondary water temp/pressure + valve control
Cooling tower fan speed control
2.3 Light Industry & Automation Machinery
บรรจุภัณฑ์, filling, sealing machines (level/weight control)
Small machine tools, hydraulic systems (ความดัน + proportional valve control)
Conveyor speed adjustment, material height detection
Food machinery: เครื่องผสม, blenders, oven temperature control
2.4 Small Chemical & Batching Systems
Temperature and pressure monitoring for small reactors
Liquid batching and proportional mixing
Dosing systems: metering pump flow control
Tank level and temperature remote monitoring
2.5 Environmental Equipment
Bag filter differential pressure + fan control
Small desulfurization and denitrification regulation
Exhaust fan and spray pump control
2.6 Building Automation & Small Facilities
Building AHU and fresh air units
Ventilation pressure control in underground garages
Small heating and heat exchanger stations
2.7 Small Boilers & Heating Systems
Hot water boiler temperature, ความดัน, level monitoring
Circulation pump variable-speed control
Analog control of burner damper/fuel valve
2.8 Hydraulic & Pneumatic Equipment
Hydraulic power unit pressure monitoring
Proportional pressure/flow valve control
Precision position control of pneumatic actuators
- Ideal Project Characteristics for EM 235
Small system: 1 ซีพียู + few expansion modules
Requires 2–4 analog inputs and 1 analog control output
Compact space, cost-sensitive
Standard industrial signals: 0–10V / 0–20mA / 4–20mA
Single closed-loop control (อุณหภูมิ, ความดัน, level, tension)
- Summary of Typical Applications
The EM 235 is widely used in small automation machines, pump stations, HVAC units, constant-pressure water supply, and temperature control systems
where multi-channel analog acquisition plus single-channel analog closed-loop control is required.
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