Simulated

The simulated driver holds its state in the client process and speaks to no real device. It exists so PLC4X functionality can be exercised and demonstrated without a PLC to connect to, and it is the driver most people reach for first when learning PLC4X.

Supported Operations

Name	Value	Description
	`read`	Supports all standard IEC 61131 data types outlined below.
	`write`	Supports all standard IEC 61131 data types outlined below.
	`subscribe`	Java only, and a real implementation rather than polling-emulated: it supports CYCLIC, CHANGE_OF_STATE and EVENT subscriptions directly. The Go driver’s subscriber is a stub and does not subscribe.

Connection String

The simulated driver runs entirely in-process and never opens a transport. The connection string names an in-memory device rather than an address:

simulated:{device-name}

An example connection string would look like:

simulated:foobar

Each call creates a fresh in-memory device; values written through one connection do not survive its close, and devices are not shared between connections.

Connection String Options

Name

Type

Default Value

Required

Description

Name

Simulated PLC4X Datasource

Code

simulated

Maven Dependency

<dependency>
  <groupId>org.apache.plc4x</groupId>
  <artifactId>plc4j-driver-simulated</artifactId>
  <version>1.0.0</version>
</dependency>

Supported Transports

Config options:

Tag Addresses

Addressing is implemented in C, Go and Java. See the protocol support matrix for what each implementation does.

General Format

The simulated addresses have this format:

{simulation-type}/{alias}:{data-type}[{array-size}]

If the array-size part is omitted, the default size of 1 is assumed. If the data-type part is omitted, it defaults to STRING.

	Array selection uses the shared notation - a single index, an inclusive range, and optionally the array’s declared lower bound, placed before the type. See Addressing arrays.

Simulation Types

The simulation device supports 3 different simulation types

STATE - This holds in memory a value for a given alias. This value can be read or written to, however this should only be used in conjunction with a persistent connection. Once the connection is closed the memory area is cleared.
RANDOM - This provides a new random value for each read. When writing, a log message is recorded and the value is discarded.
STDOUT - Always returns a null value when reading. When writing, a log message is recorded and the value is discarded.

Alias

Aliases are used to identify the different field addresses. They should only contain alpha-numeric and the full stop (.) character. For readability and language specific technical purposes they should be less than 256 characters.

Data Types

The following data types are supported:-

BOOL (boolean)
SINT (int 8)
USINT (uint 8)
BYTE (uint 8)
INT (int 16)
UINT (uint 16)
WORD (uint 16)
DINT (int 32)
UDINT (uint 32)
DWORD (uint 32)
LINT (int 64)
ULINT (uint 64)
LWORD (uint 64)
REAL (float)
LREAL (double)
CHAR (char)
WCHAR (2 byte char)
STRING (254 bytes)

Examples

All of these address formats are valid:-

RANDOM/foo:INT
RANDOM/foo:UDINT
RANDOM/foo[0..7]:INT
RANDOM/test[0..1]:DINT
STATE/bar:DINT
STATE/foo:String
STDOUT/foo:BOOL

Notes and Tips

The simulation driver uses a lot of the same logic templates that is used for the other drivers. It is a good way to test PLC4X functionality without having a device to connect to.