Specifications

Allen-Bradley DH+ Driver Help

ASCII Files

To access data in an ASCII file, specify a file number and character location. The default data type for all syntax is

shown in bold.

Syntax Data Type

A<file>:<char> Char, Byte

A<file>:<char> [rows][cols] Char, Byte

A<file>:<char> [cols] Char, Byte

A<file>:<word> offset>/length String

Note: The number of array elements cannot exceed the block request size specified. For more information, refer

to Communications Parameters.

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 DH+/DH-485 driver allows accessing to the character level. This means

that if the programming software A10:0=AB is used,'A' would be stored in the high byte of A10:0 and'B' would

be stored in the low byte. If the Allen-Bradley DH+ Driver is used, two assignments would be made: A10:0=A

and A10:1=B. This would result in thesame 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 236 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.

The following file numbers and maximum character locations are allowed for each model.

PLC Model File Number Max Character

SLC Family 9-999 1999

PLC-5 Family 3-999 1999

Note: All SLC Family PLCs do not support ASCII file types. For more information, refer to PLC documentation.

Example Description

A9:0 Character 0 (high byte of word 0).

A27:10 [80] 80 character array starting at character 10.

A15:0 [4] [16] 4 by 16 character array starting at character 0.

A62:0/32 32 character string starting at word offset 0.

String Files

To access data in a string file, specify a file number and an element. The only data type allowed is string, which

are 82 character null terminated arrays. The driver places the null terminator based on the string length

returned by the PLC.

Note: Arrays of strings are not supported.

Syntax Data Type

ST<file>:<element> String

The following file numbers and maximum word locations are allowed for each model.

PLC Model File Number Max Word Element Field

SLC Family 9-999 999 NA

PLC-5 Family 3-999 999 .LEN

Example Description

ST9:0 string 0.

ST18:10 string 10.