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Data Type

Access

Char, Byte*

Read/Write

Char, Byte*

Read/Write

Char, Byte*

Read/Write

String**

Read/Write

Allen-Bradley ControlLogix Ethernet Driver Help

Syntax A<file>:<char> A<file>:<char> [rows][cols] A<file>:<char> [cols] A<file>:<word offset>/length

80

PLC Model

File Number

Max Character

Micrologix

3-255

511

SLC 500 Fixed I/O

NA

NA

SLC 500 Modular I/O

9-999

1999

PLC-5 Series

3-999

1999

*The number of array elements cannot exceed the block request size specified. Internally, the PLC packs two characters per word in the file, with the high byte containing the first character and the low byte containing the second character. The PLC programming software allows access at the word level or two-character level. The Allen-Bradley ControlLogix Ethernet Driver allows accessing to the character level.

Using the programming software, "A10:0 = AB," would result in 'A' being stored in the high byte of A10:0 and 'B' being stored in the low byte. Using the Allen-Bradley ControlLogix Ethernet Driver, two assignments would be made: "A10:0 = A" and "A10:1 = B." This would result in the same data being stored in the PLC memory.

**Referencing this file as string data allows access to data at word boundaries like the programming software. The length can be up to 232 characters. If a string that is sent to the device is smaller in length than the length specified by the address, the driver null terminates the string before sending it down to the controller.

Ranges

Note: Not all Micrologix and SLC 500 PLC devices support ASCII file types. For more information, refer to the PLC's documentation.

Examples Example A9:0 A27:10 [80] A15:0 [4] [16] A62:0/32

Description character 0 (high byte of word 0) 80 character array starting at character 10 4 by 16 character array starting at character 0 32 character string starting at word offset 0

String Files

Data Type

Access

String

Read/Write

To access string files, specify a file number and an element. Strings are 82 character null terminated arrays. The driver places the null terminator based on the string length returned by the PLC. The default data types are shown in bold.

Note: Arrays are not supported for String files.

Syntax ST<file>:<element>.<field>

PLC Model

File Number

Max Word

Micrologix

9-999

999

SLC 500 Fixed I/O

NA

NA

SLC 500 Modular I/O

9-999

999

PLC-5 Series

3-999

999

Ranges

Examples

Example

Description

ST9:0

String 0

ST18:10

String 10

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