PLC Expanding the number of input/output lines

APPENDIX A   Expanding the number of input/output lines  INTRODUCTION  A.1 Differences and similarities  A.2 Marking the PLC controller  A.3 Specific case

Introduction

This appendix is an answer to the question “What if more input or output lines are needed ?”. Model detailed in the book carries the mark CPM1A-10CDR-A and is taken as an optimal for it’s price and features. Alternative models with greater number of lines include CPM1A-20CDR-A, CPM1A-30CDR-A or CPM1A-40CDR-A. The last two can be expanded with three additional modules with 20 extra I/O lines each, totaling 100 I/O lines as a maximum (if this is still insufficient, maybe it is time for you to start using some of more powerful PLC controllers).

If not even the most powerful model of CPM1A family satisfies your needs, then extra modules with 20 I/O lines are added. This form of connection reaches 100 input/outputs, which is a significant number in industrial proportions.

A.1. Differences and similarities

Taking the other model of PLC controller from CPM1A class basically doesn’t change a thing! Everything said for one model also applies to the other. Only thing that changes is the number of screw terminal and the number of bits in IR area connected to that screw terminal. If model with 10 I/O lines (model described in the book) has 6 inputs on addresses IR0000 - IR0005, then the 20 I/O lines model will have 12 inputs on addresses IR0000 - IR0011. Expanding itself should not be a problem. After taking off the cover on the right side, there is a connector which is then connected to the expansion module via flat cable. Still, it requires skill when assigning inputs and outputs because expansion increases the cost of the project. All the models and expansions of CPM1A class carry additional marks defining them more precisely.

Description	Input points	Output points	Power Supply	Model Number
10 I/O points	6 points	4 point Relay Output	100 to240 VAC, 50/60 Hz	CPM1A-10CDR-A
			24 VDC	CPM1A-10CDR-D
		Transistor NPN	24 VDC	CPM1A-l0CDT-D
		Transistor PNP	24 VDC	CPM1A-10CDT1-D
20 I/O points	12 points	8 points	100 to 240 VAC, 50/60 Hz	CPMlA-20CDR-A
			24 VDC	CPM1A-20CDR-D
		Transistor NPN	24 VDC	CPM1A-20CDT-D
		Transistor PNP	24 VDC	CPMlA-20CDT1-D
30 I/O points	18 points	12 points	100 to 240 VAC, 50/60 Hz	CPM1A-30CDR-A
			24 VDC	CPM1A-30CDR-D
		Transistor NPN	24 VDC	CPM1A-30CDT-D
		Transistor PNP	24 VDC	CPM1A-30CDT1-D
40 I/O points	24 points	16 points	100 to 240 VAC, 50/60 Hz	CPM1A-40CDR-A
			24 VDC	CPM1A-40CDR-D
		Transistor NPN	24 VDC	CPM1A-40CDT-D
		Transistor PNP	24 VDC	CPM1A-40CDT1-D

Notice that PLC controllers with 10 and 20 I/O lines do not have an expansion port. Generally speaking, if there is the slightest possibility for expansion in the project, PLC controller with 30 or 40 I/O lines should be used.

A.2. Marking the PLC controller

Marking the controller and the expansion module undergoes three criteria. The first is voltage, the second is the type of input/output and the third is number of I/O lines. The picture below is self-explanatory.

A.3. Specific case

If two 20 I/O lines expansion modules and one analog module are added to 30 I/O lines model, assigned inputs/outputs will have the addresses from the following table.

Unit		Assigned input bits	Assigned output bits
1	Central processing unit (CPM2A-30CDX-X)	IR 00000-IR 00011 and IR 00100-IR 00105	IR 01000-IR 01007 and IR 01100-IR 01103
2	Unit for I/O expansion (CPM1A-20EDxxx)	IR 00200-IR 02011	IR 01200-IR 01207
3	Analog I/O unit (CPM1A-MAD01)	IR 00300-IR 03015 and IR 00400-IR 00415	IR 01300-IR 01315
4	Unit for I/O expansion (CPM1A-EDxxx)	IR 00500-IR 00511	IR 01400-IR 01415