Monitor and script syntax

The Monitor is Renode’s command line interface (CLI). It lets you talk to Renode and control the emulation using a wide range of built-in functions. They allow you to access emulation objects like peripherals, machines, and external connectors.


If you want to learn more about the Monitor and its basic usage, visit the Using Renode chapter.

Generally, commands in Renode are executed line-by-line, and the arguments need to be separated by a space character. You can further extend the range of available functions with Python (see for examples and Using Python in Renode for instructions how to use Python to extend Renode).

Using built-in commands

Renode comes with dozens of built-in commands. You can access the full list of commands with their descriptions using the help command in the Monitor. To get more detailed information about a certain command, use help <command>, e.g.:

help start

Accessing emulation objects

To get access to commands available to your machine’s emulation objects (e.g., peripherals), you can type the object’s name and click Tab twice to activate tab completion.

Emulation objects are in a hierarchy, with sysbus being a machine’s root for all peripherals. If you want to access a UART peripheral of your machine called uart, you need to use sysbus.uart. You can use using command to set a default prefix, e.g. using sysbus allows you to refer to the UART directly:


You will find that the using sysbus command is used in most of the scripts bundled with Renode.

Passing the name of the emulation object as a command returns the full list of available methods, properties, and value fields for this object. In this list, you can find information on whether the method returns a value, what data types it accepts, and how to use it:

(machine-0) uart
The following methods are available:
 - Void AddLineHook (String contains, String pythonScript)
 - Void CloseFileBackend (String path)
 - Void CreateFileBackend (String path, Boolean immediateFlush = False)
 - Void DebugLog (String message)
 - String DumpHistoryBuffer (Int32 limit = 0)
 - Endianess GetEndianness (Endianess? defaultEndianness = null)
 - IEnumerable<tuple<string,< span="">IGPIO>> GetGPIOs ()</tuple<string,<>
 sysbus.uart MethodName param1 param2 ...
The following properties are available:
 - UInt32 BaudRate
     available for 'get'
 - Parity ParityBit
     available for 'get'
 - Int64 Size
     available for 'get'
 - Bits StopBits
     available for 'get'
 - get: sysbus.uart PropertyName
 - set: sysbus.uart PropertyName Value

To inspect the parameters of a specific method available to an object, simply provide the name of the object and the method:

(machine-0) uart WriteWordUsingByte
The following methods are available:
 - Void WriteWordUsingByte (Int64 address, UInt16 value)
 sysbus.uart MethodName param1 param2 ...

Keep in mind that if a method does not require any parameters, providing its name will invoke it:

(machine-0) machine GetTimeSourceInfo
Elapsed Virtual Time: 00:00:00.000000
Elapsed Host Time: 00:00:00.000000
Current load: NaN

Many commands require you to specify a parameter after the command when using them:

using sysbus

Accessing attributes of an object

Objects in Renode have access to different methods, properties, fields, and indexers depending on their type. The methods are required to access the parameters of a peripheral, and to do it successfully, you need to follow this syntax:

(machine) registrationPoint.peripheral MethodName param1 param2

To read the value of a byte at offset 0 from the uart peripheral registered on the sysbus you would type:

(machine-0) sysbus.uart ReadByte 0

Renode enables you to both get and set values for the object’s attributes. If you do not specify a value at the end of your command, the current value will be returned. If you want to set a value, you need to use the proper command and value at the end.

For example, to set the CyclesPerInstruction property to 0x000002, you would use:

(machine-0) cpu CyclesPerInstruction 0x000002

To get the value of this newly set property, you have to use:

(Mi-V) cpu CyclesPerInstruction

Setting indexers is very similar to setting properties, with the main difference being that you have to put your parameters in the square brackets:

(machine-0) machine IndexerName [param1 param2 ...] Value

To get the value of the indexer, use:

(machine-0) machine IndexerName [param1 param2 ...]

The last type of emulation object attribute is a field. Their values can be accessed the same as you access properties:

(machine-0) machine SystemBusName

Supported data types

The Monitor supports a wide variety of data types:

Table 1 Data types supported by the Monitor

Name of the data type



#comment or :comment










<0xdefg, 0xefgh>

relative range

<0x6 0x2>




@path/to/file or @path\ with\ spaces

logical values

true or false (case insensitive)

variables and macros





You can pass the path parameter to a function that accepts strings and it will be converted to a string. Keep in mind that the additional filename autocompletion is only available after an @ sign.

Monitor variable types

There are three ways you can create a single line variable in the Monitor:

  • $var="hello",

  • $var?="hello",

  • set var "hello".

The difference between $var= and $var?= is that the latter indicates a default value if the variable is not set. The Monitor also enables you to create multiline variables using the following syntax:

set var """


When loading a script, you can use slightly different syntax for multiline variables, with the """ mark put below the first line:

set var

Variables in Renode are contextual, which means that for each machine you can have different variables with the same name. You can access them by their full path. To create a variable within the machine context of machine-0, you would use:

(machine-0) $machine_0.var

You can also create global variables if you use the global prefix:

(monitor) $global.CWD

Most of the time, a short name (without the context prefix) should be enough to access variables.

The Monitor gives you access to two special variables: $ORIGIN and $CWD.

Other types of variables available in Renode are macros, which enable you to encapsulate fragments of your script and execute them easily. You can set a new macro using the macro command with the name of the new variable and the commands you want it to execute:

macro newMacro
> sysbus LoadELF $bin

You can create multiline macros using the Monitor multiline syntax. You can then execute your newly created macro using the runMacro command:

runMacro $newMacro

You can notice that many Renode sample scripts define the $reset macro. This macro is used whenever the machine Reset method is called by the user or via the simulation logic.

File paths

Each Renode project will require you to supply the file path to the components necessary for your project. The vast majority of them use the @ sign, which activates autocompletion suggestions and represents a path to a file:

include @/path/to/platform.repl

When interpreting a path, Renode looks in several places based on the configured internal path. By default:

  • it first checks in the Renode root directory,

  • if the file was not found in the root directory, it checks the current working directory.

You can check and modify the path configuration using the path command in Monitor.

You can also pass paths as "string", but completion suggestions will not work in that case.


In Renode, you can use paths that are absolute or relative to the current directory.

Relative paths

If you want to express a path that is relative to the currently executed Renode script (.resc) you can use the $ORIGIN variable:

include $ORIGIN/my_subscript.resc

An example of usage can be found in the fomu script.


Do not use @ at the beginning of an $ORIGIN-based path.

Keep in mind that the $ORIGIN variable is only available inside a script - it won’t work interactively in Monitor.

In Monitor, you can use a special $CWD variable to provide a path that is relative to the current working directory:

(machine-0) include $CWD/my_script.resc


There is no @ at the beginning of the $CWD-based path.


In a Robot file, you can also use another variable: ${CURDIR}. It is handled and resolved on the Robot Framework level and has nothing to do with Renode. Paths starting with ${CURDIR} are relative to the Robot file location.

An example of usage can be found in the LSM9DS1 test.

A ${CURDIR}-based paths need to be prepended with @. Since it is resolved at the Robot Framework level, for Renode, it looks like any other path provided by a user.

If you want to learn more about testing with Renode, visit chapter devoted to this topic.

Renode Script syntax

Many of your projects in Renode will involve using the same platforms and commands multiple times. This process can be accelerated significantly using .resc files, which are Renode scripts. The syntax of .resc files is the same as that of the Monitor.

To load a Renode script, use the include or i command:

include @/path/to/script.resc


You can use the start command instead of include to start your emulation immediately.

The syntax of a .resc file can be exemplified using one of many scripts built into Renode, like Nordic Semiconductor NRF52840 script, which we will cover line by line:

:name: NRF52840
:description: This script runs Zephyr Shell demo on NRF52840.

using sysbus

mach create
machine LoadPlatformDescription @platforms/cpus/nrf52840.repl


showAnalyzer uart0

macro reset
    sysbus LoadELF $bin
runMacro $reset

The first two lines are comments, and they are not interpreted by the Monitor:

:name: NRF52840
:description: This script runs Zephyr Shell demo on NRF52840.

Next, we utilize the using command to omit a prefix when referring to a peripheral. The command using sysbus enables you to refer to the CPU device with cpu instead of sysbus.cpu:

using sysbus

Then, we create a new machine

mach create

We load a platform description from the .repl file:

machine LoadPlatformDescription @platforms/cpus/nrf52840.repl

Now, we load a sample shell binary:


Next, we set up an UART analyzer for uart0:

showAnalyzer uart0

The next element of our script is a macro, which is executed every time the machine is reset.

To create a macro in your .resc you need to surround your macro’s code with """ (3 double quotation marks). The contents of your macro do not need to be indented with four spaces, but we often do it for readability.

The macro below loads the previously specified ELF file:

    sysbus LoadELF $bin

Lastly, we call the macro to run it, as it is only executed after it is invoked:

runMacro $reset

Last update: 2024-04-19