WATLOW MLS300-OIT Operator Interface Terminal (Keypad/Display),Discontinued

Watlow MLS300-OIT Operator Interface Terminal

The Watlow Anafaze MLS300-OIT is the dedicated local monitoring and configuration gateway for the MLS300 modular control system.

Although now discontinued, it remains a critical human-machine interface (HMI) for operators managing high-density thermal processes.

1. Introduction

The MLS300-OIT (Operator Interface Terminal) is a remote-mount keypad and display unit designed specifically for the MLS300 multi-loop controller series.

While the “blind” processor modules (MLS-PM) handle the logic and PID control inside the electrical cabinet, the OIT is mounted on the panel door to provide operators with real-time visibility.

It allows for setpoint adjustments, alarm acknowledgment, and full system configuration without opening the enclosure.

2. Technical Parameter Table

3. Product Advantages and Features

Rugged Construction: The front face is NEMA 4X rated, making it resistant to dust, water, and oil splashes common in industrial environments.

High-Visibility VFD: The bright green Vacuum Fluorescent Display is easily readable from a distance and at wide angles, even in low-light factory conditions.

Tactile Feedback: The membrane keypad is designed for use with gloved hands, providing positive “click” feedback for data entry.

Simplified Navigation: Features a menu-driven interface that allows operators to scroll through all 16 or 32 loops quickly.

Security Lockout: Includes software-based lockout levels to prevent unauthorized changes to critical PID parameters.

4. Application Cases

Plastic Extrusion: Monitoring barrel zone temperatures and adjusting melt setpoints directly at the machine head.

Semiconductor Cleanrooms: Flush-mounting the OIT on the exterior of a tool to monitor wafer processing without contaminating the environment.

Food Processing Ovens: Adjusting ramp/soak recipes on large-scale industrial dryers or baking tunnels.

Heat Treating: Real-time monitoring of multi-zone furnaces to ensure metallurgical compliance.

5. Other Models in the Same Series

The OIT is the “face” of a system that typically includes:

MLS300-PM: Processor Module (The “Brain” the OIT communicates with).

MLS316 / MLS332: Complete 16 and 32-loop base units.

MLS300-AIM: Analog Input Module for sensor expansion.

MLS300-CIM: Communication Interface for SCADA connectivity.

6. Installation and Maintenance

Installation

Cutout: Prepare a standard 1/8 DIN panel cutout ($45\text{mm} \times 92\text{mm}$).

Sealing: Ensure the rubber gasket is seated properly between the OIT and the panel to maintain the NEMA 4X rating.

Connection: Plug the dedicated OIT ribbon or serial cable into the “OIT” port on the MLS-PM.

Note: Never plug/unplug the OIT while the system is powered, as it can damage the serial driver.

MLS300-OIT

Maintenance

Keypad Cleaning: Use a mild detergent on a soft cloth. Avoid using sharp objects or industrial solvents (like Acetone) which will dissolve the membrane.

VFD Burn-in: If the display is left on the same screen for years, “ghosting” can occur. Use the “Screen Saver” or “Dim” feature found in the system setup menu to extend display life.

Cable Inspection: In high-vibration applications, check that the rear connector hasn’t vibrated loose, which can cause “Communication Error” messages on the screen.

7. Unique Product Description

“The Watlow MLS300-OIT is the industrial window into your thermal world. It distills the complexity of a 32-loop processor into a simple, rugged, and brilliantly bright interface.

As the frontline point of control for the Anafaze legacy, it provides the tactile reliability and visual clarity that operators need to keep production running at peak efficiency.”