A Python 3 built-in library using the Standard Commands Programming Instrumentation (SCPI) was implemented to communicate, control and operate Watlow F4T for this application.
Communication protocol for this applications is available only via TCP/IP using port 5025 implemented by Watlow. The sample program included in this implementation provides a starting point. Users interested in a full SCPI implementation can expand the implementation using the F4T SCPI in the spreadsheet found under the f4t_scpi_commands directory. It is the spreadsheet prepared and distirubted by Watlow.
Copyright (c) 2026 ESPEC North America, Inc.
This library is provided free of charge for communicating with Watlow F4T controllers using SCPI over TCP/IP. It is provided "as is", without warranty of any kind, express or implied.
Users are responsible for testing and validating this software in their own environment before using it with any equipment or process. The authors and contributors are not liable for damages, losses, equipment issues, process interruptions, or other consequences resulting from the use or misuse of this software.
The SCPI protocol for Watlow F4T is application with new firmware on F4T unit. According to Watlow, F4T Firmware revision 03:06:0011, released May 5, 2017 and higher is required.
This library makes use of the built-in Python Library. It requires importing the register/unregister.
Thus, only the standard install of Python 3 is required. This library has been tested on the following Python 3 versions:
- Python 3.6
- Python 3.8
- Python 3.9
- Python 3.13
Since the above versions (up to 3.9) already reached their end of life (EOL), current versions of Python 3 are recommended.
This implementation was originally written for GNU/Linux, but it can be used Mac OS and MS Windows platform, provided the necessary requirements and packages of Python 3 are met. To install Python 3 on MS Windows, simply navigate to the www.python.org, download the package for Windows.
The complete install of Debian and AlmaLinux, or Ubuntu GNU/Linux should include Python 3 standard install that includes the SCPI library. If Python 3 is not already installed, the following commands can be issued in the respective GNU/Linux platform:
- Debian/Ubuntu:
sudo apt install python3 - AlmaLinux:
sudo dnf install python3
Note: On AlmaLinux or Debian GNU/Linux platform, the sudo command refers to issuing the above command as root.
There are two ways to use this distribution:
- PyPI
- src folder
However, neither the PyPI package nor the src distribution folder has been published.
Until a packaged release is available, the easiest way to use this free library is to clone the repository to your local system and check out the main branch.
Clone this free library to your local system as follows:
git clone git@github.com:EspecNorthAmerica/WatlowF4T-SCPI-Lib.git
git checkout main
This implementation has been tested on various Watlow F4T with different configurations according to their installed modules for:
- Temp with cascade
- Temp and Humi single staged refrig
- Temp with single state refrig
- Temp and Humi with cascade refrig
To run the program to control and operate your Watlow F4T, issue:
- MS Windows:
python f4t_run.py - GNU/Linux:
sudo python3 f4t_run.py
For required application not implemented in the sample run program or in the Watlow SCPI spreadsheet, a better approach would be to take advantage of the free library offered from the ESPEC Chamber Connect Library, available here: ChamberConnectLibrary.
If the user prefers a quick remote communication and control of the F4T, they can check out this link for a quick and easy remote access and control of the F4T via PuTTY and SCPI commands: F4T SCPI Commands via PuTTY Terminal Emulator
Version 0.2.0
date: June 2026
This update does not change the core SCPI communication functions. The library has been reviewed and tested with newer versions of Python 3 to confirm compatibility with current Python environments.
Tested Python versions:
- Python 3.9
- Python 3.13
Notes:
- Existing example programs continue to use TCP/IP port 5025 for Watlow F4T SCPI communication.
- No changes were made to the public class names or method names.
- Users are encouraged to test the library in their own environment before using it with equipment or production processes.