The WATLOW CLS208 is a prominent model within the CLS series of digital temperature controllers, recognized for its blend of precision, reliability, and user-friendly operation. Designed as a compact, panel-mounted unit, it serves as a dedicated control point for maintaining accurate temperature setpoints in various industrial and commercial heating applications. The controller is engineered to simplify thermal process management by providing stable Proportional-Integral-Derivative (PID) control, clear process visibility, and straightforward configuration, making it a trusted component in systems where consistent temperature is vital for quality and efficiency.
The CLS208 operates on the principle of closed-loop feedback control. It continuously measures the actual process temperature using a connected sensor, such as a thermocouple or RTD. This Process Value (PV) is constantly compared to the user-defined Setpoint Value (SV). The built-in PID algorithm calculates the optimal output needed to minimize any error between the PV and SV. This output signal then modulates the connected heating (or cooling) device—be it a solid-state relay, contactor, or proportional valve—to bring the process to the desired temperature and maintain it there with minimal deviation or overshoot, ensuring process stability.
The CLS208 incorporates several features that enhance its usability and performance in industrial settings:
Dual Digital Display: A clear, backlit display simultaneously shows the Process Value (PV) and Setpoint Value (SV), providing operators with immediate, at-a-glance status of the control loop.
Intuitive Keypad Operation: Front-panel tactile keys allow for easy navigation through parameter menus, enabling straightforward setup of setpoints, PID values, alarm limits, and other configuration settings.
Advanced PID with Auto-Tune: Features a sophisticated PID algorithm with an auto-tuning function. This function automatically analyzes the thermal characteristics of the system and determines optimal P, I, and D tuning constants, simplifying setup and improving control performance.
Flexible Input Compatibility: Supports a wide range of temperature sensor inputs, including various thermocouple types (J, K, T, E, etc.) and Resistance Temperature Detectors (RTDs like Pt100), offering versatility for different application needs.
Multiple Output Options: Available with different control outputs to match the final control element, such as relay outputs for contactors, solid-state relay (SSR) drive signals, or analog outputs (4-20 mA or 0-10 V) for proportional control.
Configurable Alarm Functions: Includes programmable alarms for critical conditions like high/low temperature deviation, absolute limits, and sensor failure (break detection), with relay outputs to trigger external indicators or safety interlocks.
Communication Capabilities: Optional communication modules (e.g., for RS-485, Ethernet) allow the CLS208 to integrate into factory networks using protocols like Modbus, enabling remote monitoring and control from SCADA or PLC systems.
The following table summarizes the principal technical characteristics of the WATLOW CLS208 controller.
| Parameter | Specification |
|---|---|
| Controller Model | CLS208 |
| Primary Function | Digital PID Temperature/Process Controller |
| Display | Dual LED or LCD display (PV & SV) |
| Input Types | Thermocouple (J, K, T, E, etc.), RTD (Pt100) |
| Control Algorithm | PID with Auto-Tuning |
| Control Outputs | Relay, SSR Drive, Analog Current (4-20mA), Analog Voltage (0-10V) |
| Alarm Outputs | Configurable relay outputs |
| Power Supply | Wide-range AC (e.g., 100-240V AC, 50/60Hz) |
| Mounting | Standard DIN (48x96mm or 48x48mm) panel cutout |

The versatility and reliability of the CLS208 make it suitable for a broad spectrum of thermal control applications across industries:
Plastics Processing: Temperature control for injection molding machine barrels, hot runner systems, extruders, and hopper dryers.
Packaging Machinery: Regulating the temperature of heat seal bars, shrink tunnels, and glue applicators.
Food Service & Processing: Controlling griddles, fryers, ovens, holding cabinets, and sanitizing equipment.
Laboratory & Testing Equipment: Providing precise temperature regulation for incubators, environmental chambers, ovens, and furnaces.
Industrial HVAC: Managing duct heaters, unit heaters, and heat pumps in commercial and industrial buildings.
General Industrial Heating: Controlling process ovens, liquid heating systems, and surface heaters on industrial machinery.
Setting up the CLS208 involves a logical sequence: selecting the correct input type for the installed sensor, setting the desired control parameters (often aided by the auto-tune function), and configuring alarm setpoints. Its clear menu structure guides the user. The primary benefit of using the CLS208 is the delivery of stable and accurate temperature control, which directly translates to improved product consistency, reduced scrap, energy efficiency, and enhanced process safety. Its robust design ensures longevity in challenging plant environments.
The WATLOW CLS208 digital temperature controller stands as a proven and effective solution for a wide array of thermal management challenges. It successfully balances advanced control capabilities with operational simplicity. By delivering precise PID regulation, flexible I/O options, and a clear user interface, it provides engineers and technicians with a dependable tool to maintain critical temperature setpoints. Whether integrated into a complex machine or used as a standalone control unit, the CLS208 contributes significantly to process reliability, product quality, and overall operational efficiency in diverse heating applications.



