There are several International Electrotechnical Commission (IEC) standards related to Programmable Logic Controllers (PLCs). Some of the main IEC standards for PLCs are:

    IEC 61131-3: This standard specifies the requirements and guidelines for programming languages used in PLCs, including Ladder Diagram (LD), Function Block Diagram (FBD), and Structured Text (ST).

    IEC 61499: This standard specifies the requirements and guidelines for the design and implementation of Function Block Systems (FBS), which are distributed control systems composed of interconnected function blocks (FBs).

    IEC 61158: This standard specifies the requirements and guidelines for the communication between PLCs and other devices, including fieldbuses, industrial Ethernet, and wireless communication.

    IEC 62061: This standard specifies the requirements and guidelines for the design and implementation of safety-related functions in PLCs, including functional safety, risk assessment, and safety integrity.

    IEC 61499-3: This standard specifies the requirements and guidelines for the design and implementation of distributed control systems based on function blocks, including the communication and interoperability aspects of function blocks.

Here are a few more IEC standards related to PLCs:

    IEC 61131-1: This standard specifies the requirements and guidelines for the architecture and data model of PLCs, including the organization of data, programming languages, and I/O interfaces.

    IEC 61131-2: This standard specifies the requirements and guidelines for the design and implementation of graphical programming languages, such as Ladder Diagram (LD) and Function Block Diagram (FBD).

    IEC 61131-5: This standard specifies the requirements and guidelines for the design and implementation of programming languages for motion control in PLCs, including the organization of data and programming constructs.

    IEC 61131-6: This standard specifies the requirements and guidelines for the design and implementation of programming languages for safety-related functions in PLCs, including the organization of data and programming constructs.

    IEC 61131-7: This standard specifies the requirements and guidelines for the design and implementation of programming languages for distributed control systems based on function blocks, including the organization of data and programming constructs.

These standards provide a comprehensive set of guidelines for the design and implementation of PLC systems, and are widely used in the automation industry.