OMRON C500-NC222-E PLC

OMRON C500-NC222-E  PLC

Memory Packs

The Memory Pack fits into the slot located on the left side of the CPU. Be

cause the Memory Pack is not provided with the PC upon delivery, a Memory

Pack must be selected and installed in the CPU. There are two Memory

Packs available, either RAM or ROM, that can be used in the C500H PC.

RAM Pack

Data can be randomly written to and read from the RAM Pack, making it pos

sible to enter your own program into the CPU. However, because this is not a

fixed program, the memory of the RAM Pack is erased when power is not

supplied to the CPU or when the RAM Pack is removed from the CPU.

Two models of RAM Packs are available, which vary in memory capacity:

16K, and 24K words. Refer to Appendix C Standard Models for model num

bers.

Using a Programming Console, execute FUN (01) and a search operation to

check the amount of memory available

Data contained in the ROM Pack is stored on EPROM chips and cannot be

altered or erased during the CPU's operation. Write the user's program to the

EPROM chips and mount the chips (3 max.) on the ROM chip. The entire

pack is installed in the CPU. Once the data is written to the chip the data will

not be lost when the power to the PC is OFF

When we speak of a PC, we usually think of it as a single object. But actually

even the simplest PCs are usually composed of several different devices. In

fact a single PC can be physically spread throughout a building, but we still

call it one PC.

In this section, we will start with a Backplane and use all the Units discussed

in Section 2 Description of All Components to build a PC.

There is no single Unit that can be said to constitute a Rack PC. To build a

Rack PC, we start with a Backplane. The Backplane for the C500 is shown

below.

The Backplane is a simple device having two functions. The first is to provide

physical support for the Units to be mounted to it. The second is to provide

the connectors and electrical pathways necessary for connecting the Units

mounted to it.

The first device we will add to the Backplane is a Power Supply. The Power

Supply fits into the rightmost position on the Backplane and provides electric

ity at the voltages required by the other Units of the PC. It can also be used

to power devices other than the PC if necessary.

Power Supply

The core of the PC is the CPU. The CPU contains the program consisting of

the series of steps necessary for the control task. The CPU fits into the posi

tion directly to the left of the Power Supply

Unlike the CPU of the Package-type PC, the CPU of the Rack PC has no I/O

points built in. So, in order to complete this kind of PC we need to mount one

or more I/O Units to the Backplane. Mount the I/O Units to the Backplane by

pressing the I/O Unit firmly into position, making sure the connectors are

properly mated. Secure the Unit by tightening the mounting screws located

on the top and bottom of the Unit

I/O Units are where the control connections are made from the PC to all the

various input devices and output devices. As you can see from the figure,

there is still some space available on the right side of the Backplane. This

space is for any additional I/O Units that may be required

The figure above shows a total of eight I/O Units mounted to the Backplane.

Backplanes are available in different lengths, and can hold a different number

of I/O Units accordingly. Of course, not all I/O Units look exactly alike, but the

ones in the figure show their typical appearance. This configuration of Back

plane, Power Supply, CPU, and I/O Units is called a CPU Rack. This term

refers to the Backplane and all the Units mounted to it. However, if we want

to include more than eight I/O Units in our configuration we can add an addi