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>1.0.0</version>
</dependency>

Default Transport

tcp

Supported Transports

tcp

Config options:

station

INT

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

Socket read timeout in milliseconds. 0 means no timeout.

tcp.write-timeout-ms

INT

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

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.