Recommendations for Protecting Remote Access to the MicroLogic Trip Unit or Control Unit Through Modbus-SL

Functions Accessible Through Modbus-SL

When a PC running monitoring and control software (SCADA) is connected to the Modbus-SL network, the functions of the MicroLogic trip unit or control unit are accessible in the following cases:

The MasterPacT, ComPacT, and PowerPacT circuit breaker is connected to an IFM interface.
The ComPacT NSX and PowerPacT H-, J-, or L- frame circuit breaker is connected to BSCM Modbus SL/ULP module in Modbus mode.

Prerequisites for Establishing a Modbus-SL Connection

To establish a Modbus-SL connection with the MicroLogic trip unit or control unit, the prerequisites are:

The MicroLogic trip unit or control unit must be powered on.
The MicroLogic trip unit or control unit must be connected to an IFM interface or BSCM Modbus SL/ULP module in Modbus mode.
You must have a PC or other device (for example, PLC) running monitoring and control software (SCADA) connected to the Modbus-SL network giving remote access.
You must have a user ID and password with the appropriate access permissions to log in to EcoStruxure Power Commission software.

Recommendations for PCs Connected to Modbus-SL

To protect access to the MicroLogic trip unit or control unit from a networked PC, it is recommended to:

Keep PCs safely locked away when not in use.
Make sure that the PC that provides access to the MicroLogic trip unit or control unit using Modbus-SL (for example, through SCADA), requires a user login and password.
Enforce the use of strong passwords.
Make sure that user passwords are changed regularly.
Forbid reuse of old passwords.
Set a timer to lock the PC screen after a period of idle time.
Harden the PC by following the most recent vendor guidelines for the operating system running on your PC.
Limit the number of users allowed to access the MicroLogic trip unit or control unit from a networked PC.
Keep antivirus applications for PCs up to date.

In addition to the above precautions, you must also follow the general guidelines and recommendations for protecting your installation given in How Can I Reduce Vulnerability to Cyber Attacks?.