ROS2 custom service

[ArjanVroegop]

Description

This problem occurs using ROS2 Humble on Ubuntu 22.04.

I am implementing a custom ROS2 service server with a custom interface in ActionGraph.

My ActionGraph is simple:

• ROS2 Context (Context out connected to both ROS2 service server request and response)
• On Playback tick (Tick out connected to Ros2 service server request)
• ROS2 Service Server Request ( On received and server handle connected to ros2 service server response)
• ROS2 Service Server Response

My custom .srv file looks like this (please ignore names and data types, this is just an example):

# request fields
int32 distance
float32 speed
---
# response fields

The 'request distance' and 'request speed' field show up in the server request node, so I conclude that the .srv / ROS2 workspace has been built correctly and everything is sourced properly.

I call the server from terminal with this command:

ros2 service call /my_service my_interfaces/srv/MoveDistance "{speed: 1.3, distance: 1}"

This is what I see in the terminal:

requester: making request: my_interfaces.srv.MoveDistance_Request(distance=1, speed=1.3)

response:
my_interfaces.srv.MoveDistance_Response()

In IsaacSim, I can see that the distance value (int32) is changed into 1, as expected. The speed value (float32) causes an error:

2025-12-22T13:11:01Z [1,128,298ms] [Error] [isaacsim.ros2.bridge.plugin] Unable to write float value (nil)
2025-12-22T13:11:01Z [1,128,299ms] [Warning] [isaacsim.ros2.bridge.plugin] service package information changed. Updating OgnROS2ServiceServerResponse node interface.

Is this a bug, or is it something I'm doing wrong?

Isaac Sim version

5.1.0

Operating System (OS)

Ubuntu 22.04

GPU Name

RTX A5000

GPU Driver and CUDA versions

Driver 550.163.01 Cuda 12.4

Logs

No response

Additional information

No response

[ArjanVroegop]

I've digged a little bit deeper into this issue. What I've found:

This line of code seems to be the issue:

IsaacSim/source/extensions/isaacsim.ros2.bridge/include/isaacsim/ros2/bridge/Ros2OgnUtils.h

Line 895 in aa503a9

auto outputValue = getAttributeWritableData<float>(db.abi_node(), "outputs:" + messageField.name);

In this part of the ROS2 bridge code, data coming out of ROS2 is being translated to Action Graph. Is seems that all other data types than float get a different treatment. By changing line 895 into a similar way as other data types, I've got my problem fixed. So this is the change:

//auto outputValue = getAttributeWritableData<float>(db.abi_node(), "outputs:" + messageField.name);
auto outputValue = getAttributeWritableData<float>(
        db.abi_node(), inputOutput(isOutput) + ":" + prependStr + messageField.name);

I'm happy to provide a pull request, but it seems that you don't accept any. How to make sure this bug is fixed in a future release?

[zwdoescode]

@ArjanVroegop Thanks for bringing up this issue for our attention. Please feel free to create a PR and I will let the internal team to review. We will add the change internally if needed.

[ArjanVroegop]

I've (finally) made a PR: #483

It would be great if this change will be added, prevent me (and other) to manually build Isaacsim for a small bug.

[zwdoescode]

Thanks for your contribution! I have passed this down to the internal team and they will review it. I will close this discussion.