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I'm not sure, and I haven't tested this myself, but a latched publisher only sends the last message to any subscriber. If the mux subscribes to all it's inputs when it's started (edit: (seems like it does](https://github.com/ros/ros_comm/blob/29053c4832229efa7160fb944c05e3bc82e11540/tools/topic_tools/src/mux.cpp#L313-L321)), it will receive those messages. But, as typically only a single topic is selected as the initial input, all the other messages on the other inputs will be "lost" (not really, but as those inputs are not active, mux will not forward them).

Now you can switch to other inputs, but since the latched publisher has already sent its one-and-only message, the mux will not see any new msgs and so will not forward them.

Again: I don't know whether this is what actually happens, but it seems a logical explanation of what you are seeing.

I'm not sure, and I haven't tested this myself, but a latched publisher only sends the last message to any subscriber. If the mux subscribes to all it's inputs when it's started (edit: (seems seems like it does](https://github.com/ros/ros_comm/blob/29053c4832229efa7160fb944c05e3bc82e11540/tools/topic_tools/src/mux.cpp#L313-L321)), does), it will receive those messages. But, as typically only a single topic is selected as the initial input, all the other messages on the other inputs will be "lost" (not really, but as those inputs are not active, mux will not forward them).

Now you can switch to other inputs, but since the latched publisher has already sent its one-and-only message, the mux will not see any new msgs and so will not forward them.

Again: I don't know whether this is what actually happens, but it seems a logical explanation of what you are seeing.