FAQ: How Do I Specify a Bit in a Word?

Question:       I want to specify a bit in a word, but am unsure of the suffix to use.

 

A:        Each RTU or PLC has its own addressing scheme. The appropriate entry for any I/O tag's "Address" property is directly related to the type of I/O device configured in the tag's "I/O Device" property, and is typically a text value representing the address in the native form of the I/O device.

The data type to read or write is usually implied by the address. If it is not, the strings below may be appended to the address, separated by one or more spaces, to force the data to be interpreted as a specific type:

Suffix

Meaning

 

Suffix

Meaning

/AB3Float

Allen-Bradley PLC/3 Floating Point (4 Bytes)

 

/Float

IEEE Single Precision Floating Point (4 Bytes)

/AB5Float

Allen-Bradley PLC/5 Floating Point (4 Bytes)

 

/SByte

Signed Byte

/BCD2

2-digit (1 Byte) Binary Coded Decimal

 

/SDWord

Signed 32-bit Integer

/BCD3

3-digit (2 Bytes – lowest 12 bits) Binary Coded Decimal

 

/SWord

Signed 16-bit Integer

/BCD4

4-digit (2 Bytes) Binary Coded Decimal

 

/UByte

Unsigned Byte

/Bit

Bit  (as a number. ex: 40001/1)

 

/UDWord

Unsigned 32-bit Integer

/Double

IEEE Double Precision Floating Point (8 Bytes)

 

/UWord

Unsigned 16-bit Integer

Detailed information on different addressing schemes can be found in the sections listed below:

Allen-Bradley Addressing

Modicon Driver Addressing

Omron Addressing

OPC Client Driver Addressing