Retrofit Your Temperature Controller to Watlow's PM PLUS™ or PM LEGACY™

By:  - May 16, 2022  

With a new, best-in-class user interface and enhanced performance, Watlow’s PM PLUS™ and PM LEGACY™ temperature and process controllers are the next right answer for new and existing thermal systems. 

While Watlow’s tried and true EZ-ZONE® PM controllers offer solid performance, the next generation of these devices provides a more modern and rugged display screen and easier configuration. The best part is that these new controllers are backward compatible with certain legacy EZ-ZONE PMs and require minimal configuration. The benefits of PM PLUS and PM LEGACY make the case to update an easy decision.

What is New About the PM PLUS and PM LEGACY Controllers 

PM PLUS and PM LEGACY: Best-in-Class User Interface

A new and improved rugged enclosure and SMOOTH-TOUCH™  keypad prevent contaminants from damaging the facade and internal components, like water during spray downs, accidental immersion or damp environments. 

The modern, full-color, multilingual display is easy to read and is aesthetically pleasing. This easy presentation of information makes the PM PLUS and PM LEGACY suitable for global applications and manufacturers or producers with multilingual staff.

Multiple options for controller configuration and cross-communication allow for simple upgrading and effective streamlining of the process by eliminating the need to manually reconfigure the PM PLUS and PM LEGACY.

Some controllers in the PM family utilize Bluetooth® and link to Watlow’s EZ-LINK™, a mobile app that allows for the set-up, monitoring and adjustment of these controllers on the fly or when they are located in hard-to-reach areas. These models no longer require cables and hard-wiring to configure the controller functions and provide a cleaner and easier-to-use front panel.

Enhanced Performance Options


As an industry-leading no-frills, single loop, panel mount PID controller, PM LEGACY is ideal for basic applications and repetitive functions. Its one-touch operation is the perfect choice when searching for fundamental on-off operations or for operators looking for menu functionality without elaborate features.

Its backward compatibility with the EZ-ZONE PM makes for an easy exchange without having to modify existing structures or wiring. 

The 1/32 DIN PM LEGACY controller is the first in the industry to offer Bluetooth® capabilities in that size. This advanced technology creates a safety advantage, as the controller can be operated remotely with a security protocol that limits unauthorized access. 

The PM LEGACY also includes one universal input, the option for up to two outputs, alarms, profiling, various agency approvals and TRU-TUNE+® adaptive control. For functionality, the PM LEGACY controllers can be used as PID process controllers or as temperature limit controllers. 


The PM PLUS contains all the features and accessibility of the PM LEGACY plus the control options and configurations needed to run multiple functions within a single controller. As a panel mount controller, it is available in 1/16 DIN and has complete backward compatibility with any system that is currently using an EZ-ZONE PM controller.

Users can control more than temperature with the PM PLUS, including pressure and flow, lights, buzzers and more. Look for an updated and minimized menu with a “list of lists” structure, which was designed to simplify the process of figuring out which options are required for easy setup and launching of the system.

The PM PLUS is offered in two models: 

  • Standard PID model 

  • Integrated PID model

Both of these options come equipped with the upgraded enclosure that lacks tactile keys and buttons, has no jacks or dongles on the front and is easy to keep clean without the risk of damaging internal or external components.

The standard  PID model has three available variations (PID only, PID and ramping, PID and countdown timer) and allows for up to two outputs. An advantage to the integrated PID model is that it allows for up to four outputs. These outputs come with a vast output hardware library, and both models offer the option to isolate an input. 

Operators should determine their usage needs when deciding between the PM LEGACY and PM PLUS models. The PM PLUS is a perfect option for new developments looking for an easy-to-use powerhouse controller that can handle both simple and advanced functions.

Configuring multiple controllers has never been easier. Simply download the configurations from a previous controller to the EZ-LINK app and transfer them to other controllers via an available Bluetooth® connection that is equipped with robust security protocols explicitly designed to prevent unauthorized access or interference.

The Benefits of Immediate Retrofitting

If you are running equipment on the tried and true EZ-ZONE PM, updating controllers to the PM LEGACY or the PM PLUS with a simple process is recommended. As the EZ-ZONE PM reaches the conclusion of its product life cycle, firmware and software updates will be moved to the PM LEGACY and PM PLUS models.

Retrofitting takes just minutes and is as simple as unplugging the previous system and plugging in and wiring the PM model of your choice.

Manufacturers in development phases should take this time to retrofit designs and incorporate the new controllers and options to facilitate any system-based validation testing that may be required. Upgrading to the PM controllers provides the distinct advantage of improved overall efficiency due to ease of operation, shorter product training times and reduction in user error.

Improved menu navigation is more intuitive and comes with full-text menus that make utilization of these controllers easier and more user-friendly. 

Retrofitting your systems with one that includes enhanced Bluetooth® capability improves how and where the controllers can be installed, monitored and adjusted. Simply open the corresponding app on your mobile device and make any necessary changes on the fly.

For more information, visit or contact your local Watlow representative.



PM PLUS left face

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