Name conventions and limitations

Project names have a maximum of 32 characters beginning with a letter or single underscore followed by letters, digits, and single underscores. The last character for a project name must be a letter or digit; project names cannot end with an underscore character. Do not use reserved words, defined words, or data types for names.

Projects contain one device.

Device names have a maximum of eight (8) characters beginning with a letter or single underscore followed by letters, digits, and single underscores. Names cannot end with an underscore. Do not use reserved words, defined words, or data types for names.

POU names have a maximum of eight (8) characters beginning with a letter or single underscore followed by letters, digits, and single underscores. Do not use reserved words, defined words, or data types for names. Use unique names within a project.

Projects can contain up to 254 POUs.

The maximum number of variables is directly dependent on the

Trusted®

runtime 16-bit application.

The maximum hierarchical levels for POUs is 20

The addition (+), multiplication (*), AND (&), CAT, and OR (>=1) operators have a maximum of 32 input parameters.

Functions have a maximum of 32 parameters (31 inputs and one output).

Function parameter names have a maximum of 32 characters and must begin with a letter or single underscore followed by letters, digits, and single underscores. Do not use reserved words, defined words, or data types for names. Use unique names for the parameters of a function.

Function blocks have a maximum of 32 parameters (inputs and outputs).

Function block parameter names have a maximum of 32 characters beginning with a letter or single underscore followed by letters, digits, and single underscores. Do not use reserved words, defined words, or data types for names. Use unique names for the parameters of a function block.

The maximum number of variables depends directly on the

Trusted

runtime 16-bit application.

Variable names have a maximum of 32 characters beginning with a letter or single underscore followed by letters, digits, and single underscore characters. Do not use reserved words, defined words, or data types for names. Use unique names.

The names of variables having a defined Modbus address, initial value, or retained property are calculated by combining the variable and POU names for a maximum of 32 characters also beginning with a letter or single underscore followed by letters, digits, and single underscores.

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Boolean variables have the Boolean value TRUE (1) or FALSE (0) and can have an internal, constant, input, or output attribute.

DINT variable integer values range from -2147483647 to +2147483647 and can have an internal, constant, input, or output attribute. Integer literals must begin with a prefix identifying the base:

Real variables have six significant digits. For larger values, the maximum possible value is 3.402823466E+38 while for smaller values, the minimum possible value is 1.175494351E-38. Real literal values can be written with either decimal or scientific representation. The exponent part of a real scientific expression must be a signed integer value ranging from -37 to +37. The scientific representation uses the 'E' or 'F' letter to separate the mantissa part and the exponent. Real variables can have an internal, constant, input, or output attribute.

Time variables can have positive values ranging from 0 to 23h59m59s999ms. The time literal value must begin with the "T#" or "TIME#" prefix. Time variables can have an internal or constant attribute.

MESSAGE variable string capacity has a maximum of 252 characters excluding the terminating null character (0), a byte for the current length of the string, and a byte for the maximum length of the string. Characters must be preceded and followed by single quote (') characters. When placing single quote (') characters within a message literal, these characters must be preceded by the dollar ($) character.

Modbus

addresses depend on the data type and extended attributes of a variable. These are the available address ranges for the possible data types:

Defined word names have a maximum of 32 characters beginning with a letter or single underscore followed by letters, digits, and single underscore characters. Do not use reserved words, defined words, or data types for names. Use unique names within a project.

Defined word equivalents have a maximum of 255 characters.

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programs have a maximum of 255 defined words.

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projects have a maximum of 3554 defined words.

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The maximum number of I/O module instances depends directly on the

Trusted

runtime 16-bit application.

A hardware rack has a maximum of 255 I/O boards

A project has a maximum of 255 single I/O boards.

Each I/O board has a maximum of 128 I/O channels. These channels can be inputs or outputs.

The I/O module order ranges from 0 to 254

Conversion table names have a maximum of 16 characters beginning with a letter or single underscore followed by letters, digits, and single underscores. Do not use reserved words, defined words, or data types for names.

Label elements have a maximum of 32 characters beginning with a letter or single underscore followed by letters, digits, and single underscores.

Label elements have a maximum of 455 characters beginning with a letter followed by letters, digits, and single underscores.

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ST statements (one line of code) are recommended to have less than 4096 characters.

Instruction lists are not supported.

Flow charts are not supported.

Sequential function charts are not supported.