
Definition of Variables
Use
You define variables if you want to transfer the value of a message characteristic to another process instruction.
You can define variables in the following cases, for example:
You can define a variable for every message characteristic of a process instruction. The data type of the variable is identical to that of the message characteristic (for example, CHAR or NUM).
The following types of variables are distinguished:
Can only be used in the same PI sheet or cockpit in which they were defined
You use characteristic PPPI_VARIABLE.
You use characteristic PPPI_GLOBAL_VARIABLE.
For more information on Manufacturing Data Access, see:
Activity
Simple Variables
You define a simple variable by assigning the following characteristic to the process instruction immediately before the message characteristic whose value you want to transfer to the variable:
|
Characteristic |
Meaning |
Value |
|
PPPI_VARIABLE |
Simple variable that can only be used within one PI sheet or cockpit |
New variable name |
Example for simple variables
The simple variable VAR is defined for the input value "Material quantity". The value of variable VAR is to be displayed somewhere else in the PI sheet.
Process instruction 0010:
|
PPPI_INPUT_REQUEST |
Material quantity |
|
|
PPPI_VARIABLE |
VAR |
|
|
PPPI_REQUESTED_VALUE |
PPPI_MATERIAL_QUANTITY |
Process instruction 0020:
|
PPPI_OUTPUT_TEXT |
Material quantity |
|
|
PPPI_OUTPUT_VARIABLE |
VAR |
Global Variables
You define a global variable by assigning the following characteristic to the process instruction immediately before the message characteristic whose value you want to transfer to the variable:
|
Characteristic |
Meaning |
Value |
|
PPPI_GLOBAL_VARIABLE |
Global variable that can be exchanged between different PI sheets and cockpits |
New variable name |
Example for global variables
A totals calculation is to be executed in cockpit PMC1. The global variable VARSUM was defined for the value calculated.
The value of variable VARSUM is to be read in cockpit PMC2 as a data point using Manufacturing Data Access and transferred to the simple variable VARLC. The value calculated is to be displayed in cockpit PMC2.
Cockpit PMC1:
|
PPPI_INPUT_REQUEST |
Calculate value |
|
|
PPPI_GLOBAL_VARIABLE |
VARSUM |
|
|
PPPI_CALCULATED_VALUE |
PPPI_MATERIAL_CONSUMED |
|
|
PPPI_CALCULATION_FORMULA |
VAR1 + VAR2 |
Cockpit PMC2:
|
PPPI_DATA_ACCESS |
Manufacturing Data Access |
|
|
PPPI_BUTTON_TEXT |
Read value from PCM1 |
|
|
PPPI_FUNCTION_DURING_DISPLAY |
Permitted |
|
|
PPPI_IMPORT_DATA |
PMC:0001.PMC1.VARSUM |
|
|
PPPI_STRING_VARIABLE |
VARLC |
|
|
PPPI_OUTPUT_TEXT |
Value calculated |
|
|
PPPI_VARIABLE |
VARLC |
Note the following:
In general, you can choose any name for a variable. To avoid conflicts with other functions, do not use:
For more information, see Using Variables in Browser-Based PI Sheets.