AB-ETH

AB-ETH speaks the Allen-Bradley DF1 protocol tunnelled over Ethernet (the "PCCC over Ethernet/IP" encapsulation used by older Allen-Bradley/Rockwell PLC-5 and SLC 500 controllers). It addresses data in the controller’s file-based memory (integer files, status files, timers, counters, and so on) rather than by symbolic tag name.

Supported Operations

Name Value Description

read

Reads a single element (or an array of elements) from a file.

subscribe

Polling-emulated. AB-ETH has no native subscription or change notification mechanism. Subscriptions are emulated by polling the tag on the regular read path (cyclic and change-of-state subscriptions are both supported this way).

write

Not supported, in either the Java or the Go driver.

browse

Not supported.

Connection String

ab-eth://<host>[:<port>]

Example, over the default tcp transport:

ab-eth://192.168.24.40

Connection String Options

Name

Type

Default Value

Required

Description

Name

Allen Bradley ETH

Code

ab-eth

Maven Dependency

 
<dependency>
  <groupId>org.apache.plc4x</groupId>
  <artifactId>plc4j-driver-ab-eth</artifactId>
  <version>1.1.0</version>
</dependency>

Default Transport

tcp

Supported Transports

  • tcp

Config options:

station

INT

0

Id of the station we want to connect to.

request-timeout-ms

INT

10000

Maximum time (in milliseconds) to wait for the gateway to acknowledge the connection request or for a read response.

Transport config options:

tcp

tcp.connect-timeout-ms

INT

5000

Connection timeout in milliseconds.

tcp.read-timeout-ms

INT

0

Socket read timeout in milliseconds. 0 means no timeout.

tcp.write-timeout-ms

INT

0

Socket write timeout in milliseconds. 0 means no timeout.

tcp.no-delay

BOOLEAN

true

Enable TCP_NODELAY (disable Nagle’s algorithm).

tcp.keep-alive

BOOLEAN

false

Enable SO_KEEPALIVE.

tcp.send-buffer-size

INT

81920

Send buffer size in bytes. 0 uses system default.

tcp.receive-buffer-size

INT

81920

Receive buffer size in bytes. 0 uses system default.

tcp.local-address

STRING

Local address to bind to (optional). If not set, uses default.

tcp.local-port

INT

0

Local port to bind to (optional). 0 uses ephemeral port.

Tag Addresses

Addressing is implemented in Java. The Go driver reads but does not write. See the protocol support matrix for what each implementation does.

General Format

N<fileNumber>:<elementNumber>[/<bitNumber>]:<dataType>[[<size>]]

  • fileNumber - the integer file number (1 to 7 digits).

  • elementNumber - the element number within that file (1 to 7 digits).

  • bitNumber - optional; a bit within the addressed element (1 to 7 digits), separated from the element number by /.

  • dataType - the data type to interpret the element as; see Data Types below.

  • size - optional; the number of bytes to read, in square brackets. WORD and SINGLEBIT always use a fixed 2-byte size and DWORD always uses a fixed 4-byte size, regardless of what is given here; every other data type requires this to be given explicitly.

Data Types

The dataType segment is matched case-insensitively against the driver’s FileType enum:

Type Notes

STATUS

Processor status file.

BIT

Bit file.

TIMER

Timer file.

COUNTER

Counter file.

CONTROL

Control file.

INTEGER

Integer file.

FLOAT

Floating-point file.

OUTPUT

Output file.

INPUT

Input file.

STRING

String file.

ASCII

ASCII file.

BCD

Binary-coded decimal file.

WORD

Custom 2-byte integer, read from an integer file. Fixed 2-byte size.

DWORD

Custom 4-byte integer, read from an integer file. Fixed 4-byte size.

SINGLEBIT

Custom single bit, read from an integer file. Fixed 2-byte size.

Examples

N7:0:WORD

Element 0 of integer file 7, read as a 2-byte WORD.

N7:5:DWORD

Element 5 of integer file 7, read as a 4-byte DWORD.

N7:3:INTEGER[8]

Element 3 of integer file 7, read as an INTEGER with an explicit 8-byte size.

N7:0/3:WORD

Bit 3 of element 0 in integer file 7, read as a WORD.