Allen Bradley PLC Timer TT with TON

In the realm of industrial automation, Allen Bradley Programmable Logic Controllers (PLCs) are widely recognized for their versatility and reliability. Among the numerous instructions available within the PLC programming environment, timers play a crucial role in controlling and managing time-dependent operations.

One such timer instruction is the **TON (Timer On Delay)**, which is part of the **Timer TT** instruction family. This instruction allows you to create a time delay that is activated when a specific input condition is met. In this blog post, we will delve into the intricacies of the Allen Bradley PLC Timer TT with TON function, providing a comprehensive understanding of its operation and practical applications.

Understanding PLC Timers

Before diving into the specifics of the TON instruction, let’s first grasp the fundamental concept of PLC timers. A timer, in essence, is a digital circuit that measures a specific duration of time. In the context of PLCs, timers are used to:

• Control the timing of events: Timers enable you to introduce delays into your PLC program, ensuring that certain actions occur only after a predefined time interval.
• Monitor process durations: By using timers, you can track the time spent on various tasks within your automation system.
• Implement time-based logic: Timers can be integrated into complex PLC programs to create sophisticated logic that responds to time-dependent conditions.

The Timer TT with TON Instruction

The Timer TT instruction family encompasses various timer functions, including the TON instruction. The TON instruction stands for **Timer On Delay** and is a common and versatile timer type used in PLC programming.

Here’s how the TON instruction works:

1. Enable Input: When the enable input of the TON instruction is activated (typically by a logic signal), the timer starts counting.
2. Time Accumulation: The timer accumulates time until it reaches the preset value.
3. Output Activation: Once the timer reaches the preset time, its output is activated, indicating that the specified delay has elapsed.
4. Reset Input: The timer can be reset by deactivating the enable input or by applying a separate reset input.

Practical Applications of the TON Instruction

The TON instruction has numerous practical applications in industrial automation, including:

• Delaying motor starts: You can use a TON instruction to delay the start of a motor after a power-up event, preventing sudden current surges.
• Controlling conveyor belt operations: By using a TON instruction, you can control the dwell time of items on a conveyor belt, ensuring proper processing or inspection.
• Implementing safety interlocks: The TON instruction can be used to create safety interlocks, delaying certain operations until a predetermined time has elapsed.
• Controlling heating and cooling systems: TON instructions can be used to regulate the on and off times of heating or cooling systems, optimizing energy consumption.

Configuring the TON Instruction

To configure the TON instruction in your Allen Bradley PLC program, you will typically need to define the following parameters:

• Enable Input: The input that triggers the timer to start counting.
• Preset Value: The desired time delay in milliseconds, seconds, or minutes.
• Output: The output that is activated when the timer reaches the preset value.
• Reset Input (optional): An input that can reset the timer before it reaches the preset value.

Example Program: Controlling a Motor Start Delay

Let’s consider a simple example program where we use the TON instruction to delay the start of a motor by 5 seconds after a power-up event.

Program Logic:

1. Upon power-up, the enable input of the TON instruction is activated.
2. The timer starts counting and reaches the preset value of 5 seconds.
3. After 5 seconds, the timer’s output is activated, triggering the motor start command.

PLC Code (Ladder Logic):

“`
// Define the TON instruction
TON Timer1

// Set the preset value to 5 seconds
Timer1.PRE := 5000

// Enable the timer on power-up
Timer1.EN := PowerUp

// Start the motor when the timer reaches the preset value
MotorStart := Timer1.Q
“`

Conclusion

The Allen Bradley PLC Timer TT with TON instruction is a powerful and versatile tool for controlling time-dependent operations in industrial automation. By understanding its functionality and practical applications, you can effectively incorporate it into your PLC programs to enhance the efficiency and reliability of your automation systems.