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Defining Tag Data Types

When defining tags (or 'named data') for the WebPort or associated programmable logic controllers (PLCs), you must associate each data tag with an RSLogix 5000 data type.

The following rules apply to tag definition:

  • Tags cannot begin with $. This character is reserved for system definitions that you may not change. If you try to create a tag with a $ in front of it, the $ is not accepted as a character.
  • The tag name cannot match an existing tag. If you try to enter a tag name that already exists, the software will inform you that a tag with that name already exists.

The WebPort maps tag types for Modbus protocols as follows:

Tag Properties Data Type Data Range
BOOL BOOL (0 or 1)
Unsigned INT (16-bit) 0 to 65535
Signed INT (16-bit) -32768 to +32767
Unsigned DINT (32-bit) 0 to 4294967295
Signed DINT (32-bit) -2147483647 to +2147483647
REAL REAL Three ranges as follows:
  • -3.40282338 to -1.1754944-38 (negative values)
  • 0
  • 1.1754944E-38 to 3.40282338 (positive values)
STRING STRING

The WebPort maps tag types for non-Modbus protocols as follows:

Tag Properties Data Type Data Type Selection
BOOL BOOL (0 or 1)
Signed INT (16-bit) INT (-32768 to +32767)
Signed INT (8-bit) SINT (-128 to +127)
Signed INT (32-bit) DINT (-2147483647 to +2147483647)
REAL REAL Three ranges as follows:
  • -3.40282338 to -1.1754944-38 (negative values)
  • 0
  • 1.1754944E-38 to 3.40282338 (positive values)
STRING STRING

The following table lists the RSLogix 5000 data types available for tag definition:

Item Description
Bool A Boolean value is TRUE/FALSE. Examples: 0 or 1, ON or OFF, MIN or MAX
DINT A DINT data type is a signed (+/-), 32-bit integer (no decimal point). Example: 2147483647
INT An INT data type is a 16-bit integer (no decimal point). Example: 32767
SINT A SINT data type is an 8-bit integer (no decimal point). Example: -127 to 127
REAL A REAL data type is a 32-bit integer that provides an approximation of a real number. Usually called floating point. Example: 32.611328
STRING A STRING data type is a user-defined data type or structure. Usually contains alphanumeric characters (letters of the alphabet, blank spaces, periods, plus digits). Example: CentrifugeOne

The following table lists MODBUS extended addressing information for both value ranges available for this protocol:

Modbus Standard Address Format IO Type Access Register Address
Coil Digital Output Read/Write 1 to 9999
Contact Digital Input Read 10001 to 19999
Input Register Analog Input Read 30001 to 39999
Holding Register Analog Output Read/Write 40001 to 49999
Output Coil Digital Output Write 50001 to 59999

The following table lists the general format of value names for SLC 500 and Microcontroller data:

File Type ID File Type Default File Number Fields Allowed
O Output 0 -
I Input 1 -
S Status 2 -
B Binary 3 -
T Timer 4 -
C Counter 5 -
R Control 6 -
N Integer 7 -
F Floating 8 -
A ASCII none -

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