TOF

Timer Off Delay

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Libraries:

Description

The TOF block implements the TOF ladder logic instruction. When the rung conditions are true, the block accumulates time until:

• The timer is disabled

• The timer completes

Ports

Input

EnableIn — Enable Input

off (default) | on

Controls the execution of the block. EnableIn reflects the rung state preceding the block. If the rung state preceding the block is false, EnableIn is false, the block does not execute and the outputs are not updated.

Output

EN — Enable Output

off (default) | on

By default, EnableOut follows the state of EnableIn. If the EnableIn input to the block is false, the logic implemented by the block is not executed and EnableOut signal is set to false.

Parameters

Timer Tag — Timer Structure

T (default) | character vector

Specify the timer parameters in the format of tags. In Ladder Diagrams, tags (variables) are used to represent inputs, outputs, and internal memory with attributes such as Data Type, Initial Value, and size. To change the attributes of the Operand Tag, open the Program Variables table within the Ladder Diagram Program block. The Data Type of the timer tag is of the Bus:TIMER type with its initial value specified as a structure containing the following fields:

Field	Description	Default Value
PRE	The preset value specifies the value (1 millisecond units) which the accumulated value must reach before the instruction indicates it is done	0
ACC	The accumulated value specifies the number of milliseconds that have elapsed since the TOF instruction was enabled.	0
EN	The enable bit contains rung-condition-in when the instruction was last executed.	0
TT	The timing bit when set indicates the timing operation is in process.	0
DN	The done bit when set indicates the timing operation is complete (or paused).	0

Programmatic Use

Block Parameter: PLCOperandTag

Type: character vector

Value: character vector

Default: 'T'

More About

Setting Timer Preset Values

When setting the fields in the Timer Tag parameter, you must set the timer preset value, PRE, in milliseconds. When the value of the timer accumulated value field, ACC, equals the preset value, the block sets the DN bit to 1 for the TON and RTO blocks and 0 for the TOF block.

Before you set the timer preset values:

1. Load the built-in timer data types by using the plcloadtypes function. At the MATLAB^® command line, enter:

   plcloadtypes

2. Open the ladder diagram block library. At the MATLAB command line, enter:

   plcladderlib

3. Select a PLC Controller Suite block and add it to your model. Navigate to the ladder diagram program by double-clicking PLC Controller Suite > Task > Program. Alternatively, you can:

   • Add a JSR (RTN) Subroutine block and navigate to the ladder diagram program block by double-clicking JSR (RTN) Subroutine > Routine Logic.

   • Add a Function Block (AOI) block and navigate to the ladder diagram program block by double-clicking Function Block (AOI) > Logic Routine.

4. Add a TON, TOF, or RTO block to the ladder diagram program. Double-click the TON, TOF, or RTO block and enter a name. For example, name your block as T1.

5. When you add a TON, TOF, or RTO block, Simulink^® PLC Coder™ creates the associated timer structure and names your structure as TimerName_InitialValue. For example, if your timer block name is T1, the structure name is T1_InitialValue.

To set the timer preset values you can:

• Assign the timer preset values at the MATLAB command line. For example, if your block names are T1, T2, and T3, at the MATLAB command line, enter:

  T1_InitialValue = FB_TON.InitialValue;
  T1_InitialValue.PRE = 5000;
   
  T2_InitialValue = FB_TOF.InitialValue;
  T2_InitialValue.PRE = 5000;
   
  T3_InitialValue = FB_RTO.InitialValue;
  T3_InitialValue.PRE = 5000;

• Use a MATLAB script that executes when the model loads. For example, if your block names are T1, T2, and T3, in the InitFcn model callback property, enter:

  T1_InitialValue = FB_TON.InitialValue;
  T1_InitialValue.PRE = 5000;
   
  T2_InitialValue = FB_TOF.InitialValue;
  T2_InitialValue.PRE = 5000;
   
  T3_InitialValue = FB_RTO.InitialValue;
  T3_InitialValue.PRE = 5000;

• Set the timer preset values by using a MATLAB script file. You must first create a script file and then call the script file in the LoadFcn model callback. For example, create a script file called mytimerpresets. In this script file, enter:

  T1_InitialValue = FB_TON.InitialValue;
  T1_InitialValue.PRE = 5000;
   
  T2_InitialValue = FB_TOF.InitialValue;
  T2_InitialValue.PRE = 5000;
   
  T3_InitialValue = FB_RTO.InitialValue;
  T3_InitialValue.PRE = 5000;

  To programmaticaly assign the mytimerpresets script file to the LoadFcn callback, at the MATLAB command line, enter:

  set_param(gcb,'LoadFcn',mytimerpresets);

Version History

Introduced in R2019a