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SICKAG / sick_scan_xd

Based on the sick_scan drivers for ROS1, sick_scan_xd merges sick_scan, sick_scan2 and sick_scan_base repositories. The driver supports both Linux (native, ROS1, ROS2) and Windows (native and ROS2).
Apache License 2.0
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cannot re-init api in native windows application #218

Closed derivativerobmc closed 8 months ago

derivativerobmc commented 10 months ago

I'm trying to integrate SICK support into our native windows application. I have a simple example working connecting to a sensor and receiving pointcloud data using the callbacks.

However, I have multiple usability problems if the user wants to change relaunch the sensor in order to change settings or fix a connection problem. I'm currently calling functions in this order:

SickScanApiLoadLibrary handle = SickScanApiCreate( launchfile ) SickScanApiInitByCli( handle, launchfile ) SickScanApiRegisterCartesianPointCloudMsg(handle)

SickScanApiDeregisterCartesianPointCloudMsg(handle); SickScanApiClose(handle); SickScanApiRelease(handle);

newHandle = SickScanApiCreate( updated launch file ) SickScanApiInitByCli( handle, launch file ) SickScanApiRegisterCartesianPointCloudMsg(handle)

Unfortunately, this never seems to work correctly because of static thread objects that seem to persist between inits. The exact problems I get depend on whether it was able to successfully connect to the sensor in the first pass or not (sometimes it freezes my whole app waiting to join a thread and sometimes it just never updates with the new data).

Am I doing this correctly or is the API even designed for restarting like this?

Also, a +1 for multi-sensor support in the same process. My initial review of the API made it sound like this was possible and its a major limitation for our user base to not be able to connect to multiple sensors in the same application.

rostest commented 10 months ago

Thanks for reporting this issue. Your calling order to reinitialize the sensor looks as intended. We will test this scenario and analyze reinitialization problems. Which sensor did you use?

Concurrent use of multiple sensors in one process is currently not supported. We recommend to use multiple processes, such that each process serves one sensor.

derivativerobmc commented 10 months ago

Thanks for looking into it. I'm happy to get your more specific callstacks or whatever else you need.

We're using a TIM551 sensor.

Re multi-sensors, I think we have a workaround by launching multiple copies of our software, but there is definitely a lot of extra overhead that way. Was it possible to connect to multiple sensors in one process using one of the older APIs? Our client was sure this had been done for them in an older project. However, even if that was true, I'm assuming you don't recommend going back to those APIs at this point?

rostest commented 10 months ago

Unfortunately, the internal state was not completely reset by function SickScanApiInit. Please find a corrected version in branch https://github.com/SICKAG/sick_scan_xd/tree/feature/api_reinit.

Your re-initialization calls should now work as expected. The usage example sick_scan_xd_api_test.cpp waits for key 'r' to repeat the lidar initialization in the same way you did. Thanks again for reporting this isssue!

derivativerobmc commented 10 months ago

Awesome, thank you. I'll give it a try shortly.