ZeroMQ remote API

The ZeroMQ remote API is one of several ways an application can connect with CoppeliaSim.

The ZeroMQ remote API allows to control a simulation (or the simulator itself) from an external application or a remote hardware (e.g. real robot, remote computer, etc.). It offers all API functions also available via a CoppeliaSim script: this includes all regular API functions (i.e. sim.* -type functions), but also all API functions provided by plugins (e.g. simOMPL.*, simUI.*, simIK.*, etc.). The ZeroMQ remoteAPI represents a very thin Python wrapper around mentioned API functions, and can be used in the exact same way as from within a CoppeliaSim script.

The ZeroMQ remote API functions are interacting with CoppeliaSim via ZeroMQ and its interface plugin to CoppeliaSim and the ZMQ remote API add-on. All this happens in a hidden fashion to the user. The remote API can let one or several external applications interact with CoppeliaSim in a stepped (i.e. synchronized with each simulation step) or non-stepped way (i.e. the normal operation mode), and even remote control of the simulator is supported (e.g. remotely loading a scene, starting, pausing or stopping a simulation for instance).

Note: the ZeroMQ remote API also runs on CoppeliaSim V4.2.0, if you follow this procedure: clone the ZeroMQ remote API repository into your CoppeliaSim/programming folder. Then use this compatibility add-on and that script, and place them into your CoppeliaSim/ and CoppeliaSim/Lua folders respectively.

See programming/zmqRemoteApi folder or its related repository for examples.

Python

ZeroMQ and CBOR are required packages:

$ /path/to/python -m pip install pyzmq
$ /path/to/python -m pip install cbor

Here a very simple example ZeroMQ remote API client code (run it in programming/zmqRemoteApi/clients/python/)

import time
from zmqRemoteApi import RemoteAPIClient
client = RemoteAPIClient()
sim = client.getobject('sim')
client.setstepping(True)

sim.startSimulation()
while (t := sim.getSimulationTime()) < 3:
    s = f'Simulation time: {t:.2f} [s]'
    print(s)
    client.step()
sim.stopSimulation()

C++

ZeroMQ is a required package:

Windows, e.g. via vcpkg:
$ vcpkg install zeromq

Ubuntu:
$ sudo apt install libzmq3-dev

macOSX, e.g. via brew:
$ brew install zeromq

Some examples can be found in programming/zmqRemoteApi/clients/cpp/. Build them with:

$ mkdir build
$ cd build
$ cmake ..
$ cmake --build . --config Release

Here another very simple C++ ZeroMQ remote API client:

#include "RemoteAPIClient.h"
#include <iostream>
#include <iomanip>

int main()
{
    RemoteAPIClient client;
    client.setStepping(true);
    client.call("sim.startSimulation", nullptr);
    float simTime=0.0f;
    while (simTime<3.0f)
    {
        std::cout << "Simulation time: " << std::setprecision(3) << simTime << " [s]" << std::endl;
        client.step();
        simTime=client.call("sim.getSimulationTime")[0].as<float>();
    }    
    client.call("sim.stopSimulation", nullptr);

    return 0;
}

Lua

Connecting 2 or more CoppeliaSim instances can easily be achieved with following simple example of a child script:

function sysCall_init()
    remoteApiClient=require'luaZmqRemoteApi'
    remoteApiClient.init('127.0.0.1',23002)
    simx=remoteApiClient.getObject('sim')
    
    remoteApiClient.setStepping(true)
    simx.startSimulation()
end

function sysCall_sensing()
    remoteApiClient.step()
end

function sysCall_cleanup()
    simx.stopSimulation()
    remoteApiClient.cleanup()
end