Defining the data type of an instruction - STEP 7

Introduction

Some instructions can be executed with several different data types. When you insert such instructions into your program, you must specify the data type for these instructions at the actual point in the program.

Specifying the data type by means of the drop-down list

To define the data type of an instruction using the drop-down list, follow these steps:

1. Insert the instruction at the required point in the program using drag-and-drop.

   The entry "???" (undefined) is displayed in the drop-down list of the inserted instruction.

2. Click the triangle in the upper corner of the drop-down list.

   The drop-down list will open to display the data types valid for the instruction.

3. Select a data type from the drop-down list.

   The selected data type is displayed.

4. If the instruction has two drop-down lists, select the data type for the instruction inputs in the left-hand drop-down list and the data type for the instruction outputs in the right-hand drop-down list.

Specifying data type by assigning tags

To define the data type of an instruction by assigning tags, follow these steps:

1. Insert the instruction at the required point in the program using drag-and-drop.

   The entry "???" (undefined) is displayed in the drop-down list of the inserted instruction.

2. At an input or output, specify a valid tag, the data type of which is to be applied as the instruction data type.

   The data type of the tag is displayed in the drop-down list.

3. Enter a valid tag at an input and a valid tag at an output if data types need to be defined for both the inputs and outputs of the instruction. The tag specified at the input determines the data type of the inputs; the tag specified at the output determines the data type of the outputs of the instruction.

Automatically specifying the data type of mathematical instructions

To automatically specify the data type for mathematical instructions, follow these steps:

1. Insert the mathematical instruction at the required point in the program using drag-and-drop.

   The entry "???" (undefined) is displayed in the drop-down list of the inserted instruction.

2. Select the "Auto" entry from the drop-down list.

3. Enter a valid tag at an input or output.

   The data type of the tag is applied as data type of the instruction. The entry in the drop-down list changes to "Auto (<Data type>)".

See also: Selecting a data type