CNC Knowledge: How to choose and choose the most suitable PLC

Choosing the Right PLC for Your Automation Needs

As the use of Programmable Logic Controllers (PLCs) continues to increase in the industrial automation sector, it can be overwhelming to navigate the various options available. Understanding the key considerations and characteristics of PLCs can help you make an informed decision, ensuring that you select the best PLC for your specific needs.

PLCs are the backbone of many industrial automation systems, providing a platform for automation, control, and monitoring. With the ever-evolving technology and changing market demands, it is crucial to choose a PLC that meets your functional requirements and provides a satisfactory return on investment. In this article, we will explore the key factors to consider when selecting a PLC, drawing from the expertise of renowned automation companies like Delta.

Reference Conditions for Selecting a PLC

Before choosing a PLC, it is essential to understand the reference conditions that will guide your selection. These conditions include:

1. Basic Capacity Characteristics: This includes the input signal voltage range, control functions, instruction processing speed, memory capacity, timer and counter functions, data stamp capacity, expansion of E/S points, and other special functions.
2. Extendable Capacities: This includes online connection with a personal computer, software compilation ease, supply of D/A or A/D conversion modules, PLC network functionality, and checks for mobile devices like step motors, servomotors, and positioning controllers.
3. PLC Power Specifications: This includes the power supply voltage range, duration of allowable power failure, protective measures for power supply and voltage, and maximum current, energy consumption, and power consumption.

PLC Input Specifications

When selecting a PLC, it is crucial to pay attention to the following input specifications:

1. Maximum Voltage Input: This ensures that the PLC can handle the maximum voltage requirements of your system.
2. Maximum Authorized Current: This ensures that the PLC can handle the maximum current requirements of your system.
3. Minimum Current when Input is 0: This ensures that the PLC can handle the minimum current requirements of your system.
4. Type of Circuit Insulation: This ensures that the PLC provides adequate protection against electrical shock.

PLC Output Specifications

When selecting a PLC, it is equally important to consider the output specifications:

1. Type and Value of External Voltage: This ensures that the PLC can handle the external voltage requirements of your system.
2. Resistive or Inductive Load: This ensures that the PLC can handle resistive or inductive loads.
3. Maximum Leakage Current Value when Output is Open: This ensures that the PLC can handle the maximum leakage current requirements of your system.
4. Reaction Time of Output Terminal at 0 and 0F: This ensures that the PLC can handle the reaction time requirements of your system.
5. Circuit Insulation Method Used in Output Circuit: This ensures that the PLC provides adequate protection against electrical shock.

Environmental Conditions

When selecting a PLC, it is important to consider the environmental conditions in which it will operate:

1. PLC Temperature Range: This ensures that the PLC can operate within the specified temperature range of your system.
2. Shock Resistance: This ensures that the PLC can withstand shock and vibrations.
3. Impact Resistance: This ensures that the PLC can withstand impact and drops.
4. Sway: This ensures that the PLC can operate effectively in swaying environments.
5. Ability to Withstand Electric Shock: This ensures that the PLC can withstand electric shock.
6. All-Resistance to System Insulation: This ensures that the PLC provides adequate protection against electrical shock.

Checking and Daily Maintenance Before Use

Before using a PLC, it is essential to conduct a series of checks and maintenance procedures to ensure its proper functioning:

1. Check the Power Supply: This ensures that the power supply is correct and does not cause any damage to the PLC.
2. Program and Inspection: This ensures that the program is correct and does not contain any errors.
3. Operation and Test: This ensures that the PLC operates correctly and functions as intended.
4. LED Indicator Lighting: This ensures that the LED indicator lights up normally, indicating that the PLC is functioning correctly.
5. Battery Tension Indicator: This ensures that the battery level is sufficient and does not cause any errors.
6. Program Error Indication: This ensures that the program error indication is displayed correctly, indicating any errors or malfunctions.

In conclusion, selecting the right PLC for your automation needs requires careful consideration of the reference conditions, basic capacity characteristics, extendable capacities, power specifications, input specifications, output specifications, environmental conditions, and checking and daily maintenance procedures. By following these guidelines, you can ensure that you select a PLC that meets your specific needs and provides a satisfactory return on investment.