Chapter 5 Cpus; Cpu Types For Series 90-30 Plcs; Embedded Cpus - GE 90-30 PLC Series Installation And Hardware Manual

CPUs
Chapter
5

CPU Types for Series 90-30 PLCs

There are numerous CPU models available for the Series 90-30 PLC which differ in speed, I/O
capacity, size of user memory, and advanced features. This variety of models gives a system
designer considerable flexibility in choosing the one best suited to the system being designed.
There are two basic types of CPUs, Embedded and Modular. The embedded types fulfill the need
for a good low cost PLC, but lack the power, expandability, and versatility of the modular systems.
In the embedded types, the CPU is built into the baseplate. In the modular types, the CPU is
contained inside a plug-in module.

Embedded CPUs

The embedded CPUs are part of an embedded CPU baseplate. In these products, the CPU and
memory integrated circuit chips are soldered to the backplane board of the baseplate. This chapter
discusses the CPU features of these products. Details about the baseplate features are located in
Chapter 2. There are three different embedded CPUs: Model 311 (IC693CPU311), Model 313
(IC693CPU313), and Model 323 (IC693CPU323). The embedded CPUs have the following basic
features:
GFK-0356Q
The CPU type cannot be changed. It is soldered to the backplane board in the baseplate.
They do not support the use of Expansion or Remote racks, so an embedded CPU baseplate
does not have an expansion connector like the modular baseplates do. This means that if you
have an application that requires more than 10 modules, you will have to use a modular CPU
system.
The models 311 and 313 are 5-slot baseplates, and the model 323 is a 10-slot baseplate. Since
they do not require a plug-in CPU module, all numbered slots, including Slot 1, can be used
for I/O or Option modules.
The memory back-up battery is located in the Power Supply module; so if the Power Supply is
unplugged from the baseplate, the battery will be disconnected from the memory circuits,
which are located on the backplane circuit board. However, the backplane circuit board
contains a high value capacitor, called a "super capacitor," that can store enough charge to
maintain the memory circuits for a short period of time if the Power Supply is removed or its
battery is disconnected. See the section "Super Capacitor Memory Backup" in Chapter 6.
These CPUs do not have a time-of-day (TOD) clock.
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