How Choose Correctly the Best PLC for my project?
When we want to innovate and create new project we always think in a PLC and all his benefits always the most important are Technical Features and Technical Price $ that's the reason you will learn the things that must to considerar Innovators and Technicals
PLC CPU:
CPU is the main Computer in a PLC, All PLCs have at least 1 CPU the most important features to consider in choose a CPU are:
- Number of Digital Inputs (DI) of the Project (Pushbuttons, Sensors 0-1, etc)
- Number of Digital Outputs (DO) of the Project (Contactors, Relays, VFD, etc), NOTE remember if the Digital Outputs are Transistor, 24 VDC or RELAY
- Communication (Ethernet TCP/IP, Serial RS232, Serial RS485)
- SOFTWARE and Price $, you can find FREE Softwares, Cheap, Medium Price and others very expensive
- Additional Inputs Sometimes you find Analog Inputs 0-10 Volts (is unusual find CPUs with AI 4-20mA)
- HSC Inputs (High Speed Counters) for Enconders (more advanced)
- Maximun Expansion Modules PLC, it means How Many Expansion Modules can add to the PLC
- Special Features, and this is very important, for example a PLC Logo! Siemens has a Display that you can Monitor and have Data register of the process, Also you can easily add a Micro SD for Dataloggers
EXPANSION MODULES DIGITAL DI/DO:
You add DI + DO Modules when the process have more Digital Signals that are more than Digital Inputs or Outputs that include the CPU:
- Main Digital elements used are Inductive Sensors, Capacitives, Pushbuttons, Buttons, Emergency Stops, all signals 0-1 for "DIGITAL INPUTS"
- The Outputs Actuators are Contactors, Electromechanical Relays, VFD Inputs and others signals 0-1 for "DIGITAL OUTPUTS"
- There are Expansion modules that include both Digital Inputs and Digital Outputs
- Remember if you gonna buy a Digital Expansion Module, the Outputs must to consider if are Transistor, 24 VDC or RELAY
EXPANSION MODULE ANALOG AI/AQ:
You add Analog Signals AI + AQ when process have Transmitters or Sensors that send or receive "Analog Signal":
- The Analog Inputs are most common in Current 4-20mA and 0-10 Volts used in Voltage, Signals come from "Sensors / Transmitters"
- The Analog Outputs most common are 0-10 Volts in Voltage and Current 4-20mA (better Volts) and from the PLC send electrical signal to "Proportional Actuators"
- Some CPUs include "Analog Inputs" available but are 0-10 Volts, not confuse
- We recommend always have almost exactly the number of Transmitters/Actuators will work in the project to buy "Analog Modules", because the price $ is a thing that you must to take in consideration
- To Understand better Analog Inputs go to Learn to Programming Analog Inputs 4-20mA in PLC Logo! Siemens
- To Understand Better Analog Outputs go to Learn to Programming Analog Outputs 0-10V in PLC Logo! Siemens
RTD TEMPERATURE MODULES:
The best way to measure TEMPERATURE is with RTD Modules because the Sensor of measuring is a "Thermocouple or PT100" with features to measure Temperature in extreme conditions that a "Normal Transmitter" can't measure:
- Almost all PLC brands have in "stock" RTD Modules to buy
- You must to consider that some PLCs have a maximun measurement rangue of Temperature, for example PLC Logo! Siemens have maximun 200°C and minimun -50°C
- These Modules have a power supply of 24 VDC in almost all cases
- To Understand better go to Learn to programming RTD Modules and Measure Temperature in a PLC Logo! Siemens
FUTURE PROJECTS:
After of all information we have reviewed, we are available to create amazing projects, but everyday the expertize is growth, after gonna learn advanced thingss:
- Dataloggers, Memory Cards and Data Registers
- Communicate 2 PLCs same or different brands
- Gateways or Special Communication Modules
- Industrial Communication by Probibus, Modbus, Profinet, CAN, etc
- But all those things are after, now is important understand 100% all the information of how choose the best PLC for my project