Watlow PM PLUS ™ PID/Integrated Limit Controller

Attention to hazardous environments: Class 1, Zone 2 models (with "12" at the end of the configuration code) require the use of explosion-proof switches. It is prohibited to plug or unplug wiring when powered on, and replacement parts must comply with hazardous environment certification.

（2） Key wiring example

Sensor wiring

Thermocouple: Connect the negative electrode (usually red) to the S1/S2 terminal, and the extension wire should be consistent with the thermocouple material (such as K-type extension wire for K-type).

RTD: 2/3 wire system, 3-wire system needs to ensure that the resistance of the three leads is consistent (≤ 20 Ω), S1 is connected to a white lead to compensate for the lead resistance.

Process signal: 4-20mA signal connected to+R1/- S1 terminal, 0-10V signal connected to+T1/- S1 terminal, requiring separate shielded wiring.

Output and communication wiring

NO-ARC relay: only connected to AC loads (85-264V AC), load current ≤ 15A, prohibited from series use, cycle time ≥ 5 seconds.

Communication wiring: RS-485 uses twisted pair cables (T+/R+connected to B, T -/R - connected to A), and a 120 Ω terminal resistor needs to be added at the end of the bus. The distance between the communication line and the power line should be ≥ 305mm.

Digital I/O: 2-point I/O model (configuration code 2/4) supports dry contact or 3-36V DC input, 6-point I/O model (configuration code C/D/M/N) expandable switch output, with a maximum load of 1.5A per channel.

Operating interface and core functions

（1） User interface

Touch buttons and display

Key functions: Home button (return to home page), left and right buttons (menu navigation), increase and decrease buttons (parameter adjustment), custom function buttons (F1/F2, can set start/stop curves, reset alarms, etc.).

Display mode: default display of process values (such as temperature), set values, and regions, supporting 4 themes (such as white background, high contrast blue background), customizable display parameters (such as output power, remaining time).

Message prompt: Automatically switch display in case of alarm/error, such as "Limit High" or "Input Error". The lock alarm can be cleared by pressing the home button.

Menu Structure

Operations List: Real time monitoring and adjustment of operating parameters (such as set values, manual power).

Setup: Configure basic parameters such as input type, control algorithm, alarm threshold, etc.

Profile: Edit curve steps (heating/holding/waiting for events).

Factory List: Calibration, password locking, factory reset (permission required).

（2） Core function operation

PID control and tuning

Auto tuning: Enter "Operations - Autotune" and select "Yes". The controller aims to achieve 90% of the set value and automatically calculates parameters such as proportional band and integration time. During the tuning period, it outputs 100% power and ensures load safety.

TRU-TUNE+adaptive: enabled in the "Setup Control Loop", automatically optimizes PID parameters by monitoring process value fluctuations, suitable for scenarios with dynamic load changes (such as batch production).

Manual tuning: If the automatic tuning effect is not good, you can manually adjust the Heat Prop. Band and Time Integral. It is recommended to set the integration time to 0 first and gradually reduce it after stabilization to eliminate static errors.

Curve Programming (Ramp/Soak)

Curve configuration: Enter the "Profile List", each curve supports 10 steps, including Time/Ramp Rate, Soak, Wait for Event/Process, Jump, etc.

Example: Set the target temperature for "Step 1 (heating up)" to 150 ° C for 30 minutes; Step 2 (insulation) lasts for 60 minutes; Set 'Step 3' to 'Hold' to maintain the final temperature.

Startup method: It can be remotely started through function keys, numerical input, or communication. It can pause/resume during operation. If the restart time is ≤ the set "Power Off Time" after power failure, the curve can be continued.

Alarm and limit control

Alarm configuration: Supports 4 alarm channels, including process alarm (fixed threshold), deviation alarm (relative set value), and can be set to lock/non lock, shield (not triggered temporarily when starting/set value changes).

Limit control: The integrated limit model (L/M) supports high/low limit, and automatically cuts off the output when it exceeds the limit. It needs to be manually reset (through buttons, digital inputs, or communication), and outputs 4 fixed limit dedicated.

Current monitoring: Equipped with a current transformer (CT) input, it can detect open/short circuits in the heater, trigger the "Heater Error" alarm, and protect the load and controller.

Communication and Remote Configuration

（1） Communication Protocol and Settings

Protocol configuration key points applicable scenarios

Bluetooth (EZ-LINK application) devices can be paired through Bluetooth after being powered on, supporting parameter reading and writing, alarm viewing, curve downloading, and quick on-site configuration without the need for physical wiring, reducing wiring costs