Comprehensive Product Summary – SUNIX ioSCADA SM_TH_108i 8-Channel Thermistor Analog Input Module

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### 1. Product Overview

Product Name: 8-Channel Thermistor Analog Input Module
Model: SM_TH_108i
Series: SUNIX ioSCADA SM Series
Article Number: SM_TH_108i
Manufacturer: SUNIX Group

The SM_TH_108i is part of the SUNIX ioSCADA family of industrial Modbus I/O modules designed for distributed data acquisition and control in SCADA, DCS, and PLC systems. It provides eight differential thermistor input channels with high accuracy, robust isolation, and industrial-grade reliability. The module supports Modbus RTU and ASCII protocols over an RS-485 three-wire interface, enabling seamless integration into industrial automation networks.

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### 2. Key Features

- Eight Differential Thermistor Channels: Supports 10K Type II and 10K Type III thermistors for precise temperature measurement.
- Wide Measurement Range: -45°C to +140°C, suitable for environmental, process, and equipment monitoring.
- High Resolution and Accuracy: 0.1°C resolution with ±0.5°C accuracy ensures reliable thermal data acquisition.
- 16-bit A/D Conversion: Provides fine measurement granularity with 140 ms per channel conversion rate.
- Industrial-Grade Isolation: 3-way isolation (RS-485, field-to-logic, and channel-to-channel) rated at 3000 Vrms for noise immunity and safety.
- Built-in Hardware Watchdog: Ensures continuous operation and automatic recovery from communication or hardware faults.
- Standard Modbus RTU/ASCII Protocol: Compatible with most SCADA and PLC systems, including Wonderware, LabView, and Citect.
- DIN-Rail Mountable Compact Design: 132 × 125 × 47.5 mm enclosure for easy integration into control panels.
- User-Friendly LED Indicators: Power, communication, and I/O status LEDs for quick diagnostics.
- High Noise Immunity: Meets IEC61000-4-4 EFT Level 3 and IEC61000-4-2 ESD Level 3 standards.
- Flexible Configuration: DIP switches for baud rate, address, and protocol selection; no software required for basic setup.
- Network Scalability: Supports up to 63 modules on a single RS-485 bus without repeaters (up to 4000 ft).

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### 3. Technical Specifications

Electrical & Signal Characteristics
- Input Channels: 8 differential
- Input Type: 10K Type II and 10K Type III thermistors
- Input Range: -45°C to +140°C
- Resolution: 0.1°C (0.18°F)
- Accuracy: ±0.5°C (0.18°F)
- A/D Conversion: 16-bit
- Conversion Time: 140 ms per channel
- Excitation Current: 200 µA DC typical (all types)
- Lead-Wire Configuration: 2-wire
- Break Detection: Supported

Electrical Isolation & Protection
- RS-485 Isolation: 3000 Vrms
- Field-to-Logic Isolation: 3000 Vrms
- Channel-to-Channel Isolation: Yes
- Overvoltage Protection: 70 VDC/Vp-p
- Network Isolation Voltage: 3 kVrms

Noise & Filtering
- Noise Filter: 50/60 Hz automatic
- Normal Mode Rejection: 60 dB @ 60 Hz
- Common Mode Rejection: 90 dB @ 60 Hz
- Input Filter Bandwidth: -3 dB at 1.5 Hz

Power & Consumption
- Power Supply: 10–30 VDC
- Typical Current Draw: 0.1146 A @ 24 VDC
- Maximum Current Draw: 0.1601 A @ 10 VDC

Physical Characteristics
- Dimensions: 132 × 125 × 47.5 mm
- Mounting: DIN-rail or panel mount
- Weight: Approx. 0.5 kg (typical)
- Wiring: Removable terminal blocks, 16–24 AWG

Environmental Conditions
- Operating Temperature: -30°C to +75°C
- Storage Temperature: -45°C to +85°C
- Relative Humidity: 5–90%, non-condensing

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### 4. Functionality

The SM_TH_108i functions as a high-precision thermistor input module for temperature monitoring and control in industrial environments. Each of its eight differential channels can independently measure temperature using 10K Type II or Type III thermistors. The module converts analog resistance values into digital temperature data using a 16-bit A/D converter and transmits the results via Modbus RTU or ASCII over RS-485.

Use Cases & Applications:
- Industrial process temperature monitoring
- HVAC and building automation systems
- Environmental and laboratory monitoring
- Energy management and equipment diagnostics
- Integration with SCADA, DCS, and PLC systems

Compatibility:
- Fully compatible with Modbus-compliant SCADA software (e.g., Wonderware, LabView, Citect, Intellution).
- Operates as a Modbus slave device with address range 1–63.
- Supports both RTU and ASCII communication modes.

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### 5. Components & Accessories

Included Items:
- SM_TH_108i module
- DIN-rail mounting accessory
- Installation CD with ioCFG configuration software
- Quick installation guide

Optional Accessories:
- RS-232/RS-485 isolation converter
- RS-485 repeater (for networks exceeding 1200 m)
- External power supply (10–30 VDC industrial-grade)

Connectors:
- Removable terminal blocks for thermistor inputs
- 3-wire RS-485 communication terminals (Data+, Data–, COM)
- Power input terminals (+V, GND)

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### 6. Installation & Setup

Mounting Options:
- DIN-rail (horizontal or vertical orientation)
- Panel mounting (front or back)

Setup Procedure:
1. Power Supply: Connect a regulated 10–30 VDC power source.
2. Communication Wiring: Use shielded twisted-pair cable for RS-485 (Data+, Data–, COM).
3. DIP Switch Configuration:
- SW1: Set baud rate (1200–115200 bps) and protocol (RTU/ASCII).
- SW2: Set Modbus slave address (1–63) and INIT (factory reset).
4. LED Indicators:
- PWR: Power status
- RX/TX: Communication activity
- IO_ACC: Module operation status
- Rt_ON: RS-485 termination resistor status
5. Software Configuration:
- Use ioCFG software (Windows-based) for advanced parameter setup, monitoring, and calibration.
- Supports auto-scan, online/offline editing, and EEPROM parameter storage.

Network Configuration:
- Up to 63 modules per RS-485 segment (4000 ft max without repeater).
- Default settings: 115.2 kbps, 8 data bits, no parity, 1 stop bit, address 1.

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### 7. Performance & Capabilities

Measurement Performance:
- Resolution: 0.1°C
- Accuracy: ±0.5°C
- Conversion Rate: 140 ms/channel
- Temperature Drift: < ±0.005% of span per °C

Processing Functions:
- Offset Adjustment: -128 to +127
- Input Smoothing: 1–255 (digital filtering)
- High/Low Alarm: Programmable thresholds per channel
- Over/Under Range & Flow Alarms: Detects abnormal input conditions
- Break Alarm: Detects open thermistor circuits
- Latch Max/Min Values: Records peak and minimum readings for diagnostics

System Reliability:
- Dual Watchdog System:
- Hardware Watchdog: Monitors CPU operation.
- Communication Watchdog: Detects Modbus link failures and triggers safe states.
- Fail-Safe Operation: Maintains last known safe output state during communication loss.
- Automatic Self-Calibration: Minimizes temperature drift and ensures long-term accuracy.

Limitations:
- Designed for thermistor inputs only (10K Type II/III).
- Not suitable for thermocouple or RTD sensors.
- Maximum network length 4000 ft without repeater.

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### 8. Standards & Compliance

Communication Standards:
- Protocol: Modbus RTU/ASCII over RS-485 (3-wire)
- Baud Rates: 1200, 2400, 4800, 9600, 19.2k, 38.4k, 57.6k, 115.2k bps
- Address Range: 1–63 (default 1)
- Network Distance: 4000 ft (1200 m) without repeater

Supported Modbus Function Codes:
1 – Read Coil Status
2 – Read Input Status
3 – Read Holding Registers
4 – Read Input Registers
5 – Force Single Coil
6 – Preset Single Register
8 – Loopback Command
15 – Force Multiple Coils
16 – Preset Multiple Registers
17 – Report Slave ID

Electrical & EMC Compliance:
- EFT Immunity: IEC61000-4-4 Level 3 (power and signal lines)
- ESD Immunity: IEC61000-4-2 Level 3 (8 kV air, 4 kV contact)
- Surge Immunity: IEC61000-4-5 (0.5 kV)
- CE Compliant

Isolation & Safety:
- 3-way isolation (RS-485, field-to-logic, channel-to-channel)
- 3000 Vrms isolation voltage
- Overvoltage protection up to 70 VDC

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### 9. Additional Information

Warranty & Service Policy:
- Warranty Period: 2 years from delivery or 1 year after installation (whichever comes first).
- Coverage: Manufacturing defects under normal operating conditions.
- Exclusions: Damage from misuse, improper installation, or environmental conditions outside specifications.
- Repair Policy:
- Free repair within warranty (shipping costs borne by customer).
- Post-warranty repairs charged at ~25% of product price.
- RMA required for all returns.

Maintenance & Support:
- Preventive Maintenance: Periodic inspection of wiring and terminal connections recommended.
- Firmware Updates: Available through SUNIX technical support.
- Technical Support: SUNIX Tech Forum and authorized distributors provide configuration and troubleshooting assistance.

Software Tools:
- ioCFG Configuration Utility:
- Windows-based GUI for parameter setup, monitoring, and diagnostics.
- Supports auto-scan of networked modules.
- Allows EEPROM parameter storage and retrieval.

Reliability & Longevity:
- Designed for harsh industrial environments with high EMI/RFI immunity.
- Long MTBF and robust mechanical design ensure extended operational life.

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### Summary

The SUNIX SM_TH_108i is a high-performance, industrial-grade 8-channel thermistor input module engineered for precise temperature measurement and reliable operation in demanding environments. Its 16-bit resolution, wide temperature range, and robust isolation make it ideal for SCADA, DCS, and PLC-based automation systems. With Modbus RTU/ASCII compatibility, hardware watchdogs, and industrial EMC compliance, the SM_TH_108i delivers dependable performance for process monitoring, environmental control, and equipment diagnostics.

Its compact DIN-rail design, user-friendly configuration, and comprehensive alarm and diagnostic functions make it a versatile and cost-effective solution for distributed temperature acquisition in industrial automation networks.