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WATLOW MLS300 Series Controller
Source: | Author:kongjiang | Published time: 2026-07-09 | 76 Views | 🔊 Click to read aloud ❚❚ ▶ | Share:
WATLOW MLS300 Series Controller

System Overview
Manual Contents

This manual describes how to install, setup, and operate a MLS316 or MLS332 controller. Each chapter covers a different aspect of your control system and may apply to different users. The following describes each chapter’s purpose.

•Chapter 1: System Overview. Provides a component list and summary of features for the MLS300 controllers.
•Chapter 2: Installation.Provides detailed instructions on installing the MLS300 controller and its peripherals.
•Chapter 3: Using the MLS300.Provides an overview ofoperator displays used for system monitoring and jobselection.
•Chapter 4: Setup.Provides detailed descriptions of allmenus and menu options for controller setup.
• Chapter 5: Extruder Options.Explains the additional features on an MLS300 controller equipped with Extruder Control Firmware.
•Chapter 6: Enhanced Features.Describes process variable retransmit, ratio, differential and cascade control features available with the enhanced features option.
•Chapter 7: Ramp/Soak.Explains how to setup and use the features of the ramp/soak option.
•Chapter 8: Tuning and Control.Describes available control algorithms and provides suggestions for applications.
•Chapter 9: Troubleshooting and Reconfiguring.Includes troubleshooting, upgrading and reconfiguring procedures for technical personnel.
•Chapter 10: Linear Scaling Examples.Provides anexample configuring a pressure sensor, a flow sensor, andan encoder using linear scaling.
•Chapter 11: Specifications.Lists detailed specificationsof the controller and optional components.
Getting Started
The following sections provide information regarding product features, technical descriptions, safety requirements, and preparation for operation.
These symbols are used throughout this manual:
Initial Inspection

Accessories may or may not be shipped in the same container as the MLS300, depending upon their size. Check the shipping invoice carefully against the contents received in all boxes.

Product Features

The MLS300 series controllers provide 16 or 32 fully independent loops of PID control. When used as a stand-alone controller, you may operate the MLS300 via the two-line 16-character display and touch keypad. You can also use it as the key element in a computer-supervised data acquisition and control system; the MLS300 can be locally or remotely controlled via an EIA/RS-232 or EIA/RS-485 serial communications interface.

The MLS300 features include:
• Direct Connection of Mixed Thermocouple Sensors:Connect most thermocouples to the controller with nohardware modifications. Thermocouple inputs feature reference junction compensation, linearization, processvariable offset calibration to correct for sensor inaccuracies, detection of broken, shorted or reversed thermocouples, and a choice of Fahrenheit or Celsius display.
• CIM300 Input Option: The CIM300 input module provides high density sensor termination with a smaller installation footprint and faster installation.
• Accepts Resistive Temperature Detectors (RTDs): Use 3-wire, 100 ohm, platinum, DIN-curve sensors with two choices for range and precision of measurements. (To use this input, order a MLS316 or MLS332 controller with scaling resistors.)
• Automatic Scaling for Linear Analog Inputs: The MLS300 series automatically scales linear inputs used with other industrial process sensors. Enter two points, and all input values are automatically scaled in your units. Scaling resistors must be installed.
• Dual Outputs: The MLS300 series includes both heat and cool outputs for up to 16 loops. Independent control parameters are provided for each output.Independently Selectable Control and Output Modes:You can set each control output to ON/OFF, Time Proportioning, Serial DAC, or Distributed Zero Crossing mode. Set up to two outputs per loop for ON/OFF, P, PI,or PID control with reverse or direct action.
• Control Outputs: Set high/low deviation and high/low process limits to operate digital outputs as on/off control functions or alarms.
• Flexible Alarm Outputs: Independently set high/lowprocess alarms and a high/low deviation band alarm foreach loop. Alarms can activate a digital output bythemselves, or they can be grouped with other alarmsto activate an output.
• Global Alarm Output: When any alarm is triggered, theGlobal Alarm Output is also triggered, and it stays on until you acknowledge it.
• CPU Watchdog: The MLS300 series CPU watchdog timer output notifies you of system failure. You can use it to hold a relay closed while the controller is running, so you are notified if the microprocessor shuts down.
• Front Panel or Computer Operation: Set up and run the controller from the front panel or from a local or remote computer. WatView software is available to configure and monitor the MLS300 from a PC.
• Modbus RTU Protocol, EIA/TIA-232 and 485 Communications: Connect to PLCs, operator interface terminals and third-party software packages using the widely supported Modbus RTU protocol.
• Multiple Job Storage: Store up to 8 jobs in memory, and access them locally by entering a single job number or remotely via digital inputs. Each job is a set of operating conditions, including set points and alarms.
• Non-Linear Output Curves: Select either of two nonlinear output curves for each control output.
• Autotuning Makes Setup Simple: Use the Autotune feature to set up your system quickly and easily. The MLS300 internal expert system table finds the correct PID parameters for your process.
• Pulse Counter Input: Use the pulse counter input for precise control of motor or belt speed.
• Low Power Shutdown: The controller shuts down and turns off all outputs when it detects the input voltage drop below the minimum safe operating level.
System Diagram
The illustration below shows how the parts of the MLS300 are connected. When unpacking your system, use the diagram and parts list below to ensure all parts have been shipped. Please don't hesitate to call Watlow Anafaze's Customer Service Department if you have problems with your shipment, or if the MLS300's components are missing or damaged.

Parts List MLS316/MLS33
You may have received one or more of the following components. Refer to Figure 1.1 on page 5 and Figure 1.2 on page 6 for MLS300 configuration information.
• MLS300 Processor Module (PM)
• Controller Mounting Kit
• 16- or 32-Channel MLS300-AIM Module with 4-foot AIM cable
• 16- or 32-Channel CIM300 Module with 4-foot AIM cable.
• EIA/RS-232 or EIA/RS-485 Communication Cable
• TB50 with 50-pin SCSI Cable
• Power Supply with Mounting Bracket and Screws
• SDAC (Serial Digital-to-Analog Converter)
• Special Input Resistors (installed in MLS300 AIM)
• User Manual
Technical Description
This section contains a technical description of each component of your MLS300 Controller.
Processor Modul
The MLS300 Processor Module (MLS300-PM) is housed inan eighth-DIN panel mount package. It contains the CPU,RAM with a built-in battery, EPROM, serial communications, digital I/O, the screen and touch keypad.
MLS300-PM Rear View
The MLS300-PM has the following features:
• Keypad and 2-line, 16-character display.
• Screw terminals for the power inputs and outputs.
• Input power is 12 to 24 Vdc at 1 amp.
• The +5 Vdc output power supply of the processor module powers the MLS300-AIM.
• The MLS300-PM interfaces with the MLS300-AIM with an 8-pin RJ-45 style connector.
• A 50-pin SCSI cable connects the digital inputs and outputs to the 50-pin terminal block (TB50).
• The MLS300 uses 6-pin, telephone-style connectors for EIA/RS-232 and EIA/RS-485 external communications.
System Overview
MLS300 Series User’s Guide
The program that operates the MLS300 is stored in a socketed, flash, static-RAM chip, so it is easy toupdate or change thefirmware. The MLS300 stores its operating parameters inbattery-backed RAM, so if there's a power loss the operating parameters are unchanged. The battery has a ten year shelflife, and it isnot used when the unit is on.The microprocessor performs all calculations for input signallinearization, PID control, alarms, and communications.
Front Panel Description
The MLS300-PM's display and touch keypad provide anintelligent way to operate the MLS300. The display has 16alphanumeric or graphic characters per line. The 8-keykeypad allows you to change the MLS300's operatingparameters, controller functions, and displays.
The MLS300's information-packed displays show processvariables, set points, and output levels for each loop. A bargraph display, single loop display, scanning display and analarm display offer a real-time view of process conditions.Two access levels allow operator changes and supervisorchanges.
TB50
The TB50 is a screw terminal interface for control wiringwhich allows you to connect relays, encoders and discrete I/Odevices to the MLS300. The screw terminal blocks acceptwires as large as 18 AWG. A 50-pin SCSI cable connects theTB50 to the MLS300-PM.
MLS300-AIM and AIM-TB
The MLS300 Analog Input Module (MLS300-AIM), consistsof the AIM-TB (AIM Terminal Board) and the AIM’s plug-incards. The MLS300-AIM receives input signals from sensorsand transmits this information to the MLS300-PM through theAIM cable.
The AIM-TB includes power supply terminals, input signalwiring screw terminals, input signal conditioning circuits, andterminal connections for the AIM's plug-in cards. It alsoincludes a cold junction temperature sensor and room for theinput scaling resistors, if required. (RTDs, inputs greater than60 mVdc, and mAdc current inputs require input scalingresistors.) The AIM-TB has three slots for the plug-in AIMcards.There are two versions of the MLS300-AIM: the AIM-16 andAIM-32. The AIM-16 has one multiplexer (MUX) card, and the AIM-32 has two MUX cards.
These cards multiplex the 16inputs each card receives. Each -10 to 60 mVdc input isconverted to a voltage that is transmitted to the Voltage/Frequency (V/F) card. (The MUX cards also automaticallycalibrate the zero and span of the analog amplifier andmeasure the cold junction compensation temperature forthermocouple inputs.) Both the AIM-16 and AIM-32 have aV/F card, which converts the input signal voltage to a frequency. The converted signal is then transmitted via theAIM cable to the MLS300-PM for processing.
CIM300
The MLS300 Compact Input Module (CIM300) consists oftwo circuit boards that perform analog-to-digital conversionand data communications to the processor module. TheCIM300 receives input signals from sensors and transmits thisinformation to the MLS300-PM through the AIM cable.
The CIM300 includes power supply terminals, input signal connectors, a communications connector and input signal conditioning circuits. It also includes a cold-junction temperature sensor and room for the input scaling resistors, if required. (RTDs, inputs greater than 60 mV dc, and mA dc current inputs require input scaling resistors.)
There are two versions of the CIM300: the CIM316 andCIM332. The CIM316 supports 16 inputs through a D-Sub 50female connector and the CIM332 supports 32 inputs through2 D-Sub 50 connectors (inputs 1 to 16 female, inputs 17 to 32male). The user supplies the mating D-Sub 50 connectors. The CIM300 has one or two multiplexer circuits that multiplex the 16 inputs each card receives. Each -10 to 60 mV dc input is converted to a voltage that is transmitted to the Voltage/Frequency (V/F) card. (The mulitplexer circuits also automatically calibrate the zero and span of the analog amplifier and measure the cold-junction compensation temperature for thermocouple (T/C) inputs.) A V/F circuit converts the input signal voltage to a frequency. Theconverted signal is then transmitted via the AIM cable to theMLS300-PM for processing.
MLS300 Cabling
Watlow Anafaze provides cables required to install yourMLS300.A 50-pin SCSI cable connects the TB50 to the MLS300-PM.
The cable connecting the MLS300-PM to the AIM-TB is an8-conductor, shielded cable with RJ-45 connectors.

The cables used to connect the MLS300 to EIA/RS-232 orEIA/RS-485 communications are 6-conductor, shielded cablewith RJ-12 connectors on one end and a DB-9 connector or bare wires on the other end.