Specifications

34 Maxim Industrial Solutions
Programmable logic controllers (PLCs)
CPU functions
Overview
The CPU functions for a PLC include
the processor, memory, and support
circuitry required to execute the
programmed instructions and
communicate with the various
I/O functions.
System monitoring functions are
performed by the CPU’s power-
supply voltage monitors; watchdog
timers (WDTs) and reset circuits;
and thermal monitors for critical
devices and hot spots. The CPU
module also includes components
to enable communications to other
modules, PLCs, PCs, and the human
interface (e.g., switch debounce,
displays, audio). Isolated power
supplies, hot-swap controllers, and
battery backup combine for power
management.
Security functions
Security and authentication compo-
nents prevent unauthorized system
control or access to system data. The
complexity of security components
varies depending on the level of
security required. Typical security
components include security
managers with tamper detection
and nonimprinting memory, secure
microcontrollers with authentication,
and 1-Wire® authentication devices
with an integrated SHA-1 algorithm.
Secure components require several
specific features, including tamper
detection; fast-erasing memory for
storage of secret data; analysis-
resistant encryption engines; and
support for PCI PED 2.1, FIPS 140.2
(level 3 and above), EMV® 4.1, and
Common Criteria requirements.
CPU functions
Block diagram of PLC CPU functions. For a list of Maxim's recommended PLC solutions, please go to: www.maxim-ic.com/plc.
µP
CPU
FPGA
THERMAL
MANAGEMENT
1-WIRE INTERFACE
AND
AUTHENTICATION
DISPLAY
DRIVERS
CODECS
SECURE-µP
VOLTAGE
MONITORS
CLOCK
WATCHDOG
TIMER
RESET ICs
TO DISPLAY
AUDIO OUTPUT
HOT-SWAP
CONTROLLER
ISOLATED POWER SUPPLY
TO ALL
BATTERY
BACKUP
SWITCH
DEBOUNCER
TOUCH SCREENBACKLIGHT
AUDIO AMPLIFIER
FILTERS
SECURITY MANAGER
USB
= MAXIM SOLUTION