Role of the CPU in a Control System

In a modular PAC, the CPU controls and processes the application. The local rack identifies the rack that contains the CPU. In addition to the CPU, the local rack contains a power supply module and may contain communication processing modules and input/output (I/O) modules.

The CPU is in charge of:

  • configuring all modules and device present in the PAC configuration

  • processing the application

  • reading the inputs at the beginning of tasks and applying the outputs at the end of tasks

  • managing explicit and implicit communications

Modules may reside in the local rack with the CPU or they may be installed in remote drops at a distance from the local rack. The CPU has built-in capabilities to act as the RIO processor that manages communications between the CPU and the Quantum and X80 EIO adapter modules that are installed in each remote drop.

Devices can be connected to the PAC network as either DIO clouds or DIO sub-rings.

For detailed information about the various architectures that the M580 network supports, refer to chapter Planning and Designing a Typical M580 Network. For a detailed description of the X80 EIO adapter modules and the options they provide for installing a remote drop, refer to Modicon M580, Remote I/O Modules Installation and Configuration Guide.

Functional Considerations

The CPU solves control logic for the I/O modules and distributed equipment in the system. Choose a CPU based on several operating characteristics:

  • memory size

  • processing power: the number of I/O points or channels that it can manage

  • the speed at which the CPU can execute the control logic

  • communication capabilities: the types of Ethernet ports on the CPU

  • the number of local I/O modules and RIO drops that it can support

  • the ability to function in harsh environments: (3 CPU modules are hardened to operate over extended temperature ranges and in dirty or corrosive environments

  • network configuration (standalone or Hot Standby)

Standalone CPU Modules

This is a list of the available CPU modules. Some are available in both standard and industrially hardened modules. Industrially hardened modules have the letter H appended to the module name. The letter C at the end of the module name indicates a conformal coating for harsh environments:

  • BMEP581020, BMEP581020H

  • BMEP582020, BMEP582020H

  • BMEP582040, BMEP582040H, BMEP582040S

  • BMEP583020

  • BMEP583040

  • BMEP584020

  • BMEP584040, BMEP584040S

  • BMEP585040, BMEP585040C

  • BMEP586040, BMEP586040C, BMEP586040S

CPU modules ending with “S” are safety modules. Refer to the Modicon M580 Safety System Planning Guide for a description of safety CPUs.

Hot Standby CPU Modules

These CPU modules are compatible with M580 Hot Standby systems:

  • BMEH582040, BMEH582040C, BMEH582040S

  • BMEH584040, BMEH584040C, BMEH584040S

  • BMEH586040, BMEH586040C, BMEH586040S

NOTE: For detailed information about M580 Hot Standby configurations, refer to the Modicon M580 Hot Standby System Planning Guide for Frequently Used Architectures.

Altitude Operating Conditions

The characteristics apply to the CPU modules for use at altitude up to 2000 m (6560 ft). When the CPU modules operate above 2000 m (6560 ft), apply additional derating.

For detailed information, refer to chapter Operating and Storage Conditions.