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Expansion Hub Disconnecting/Becoming Unresponsive #473
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Can you give us more information about the Electronics configuration? Are you using a Control Hub or a phone as your primary control device? How is the expansion hub connected? Are you using a USB hub, and if so what kind? I'm leaning towards a USB power issue, if you're not using a powered USB hub between a phone and the expansion hub the camera may consume too much power and it causes the USB subsystem to brown out and reset. But, I don't have enough information yet to say that for certain. |
We are using a control hub as the primary to which the camera, drive motors, and three servors are connected. The expansion hub is connected by the RS 485 port and has two motors and three servos attached to it. Would a USB connection between the Control Hub and Expansion Hub be better than the 485 port? Thanks |
"Better" is up for debate depending upon the context of the question. In this context, I think you're asking if it's "better" in terms of connection integrity. A USB connection may have less mechanical connection strength than the 3-wire RS485 connection you currently have, though the USB cable would have better shielding/protection for the wires. One of the big problematic areas is wire failure; over time constant bending of the wires or having the wires exposed to other mechanical systems can cause the wires to fail, leading to shorts and other issues. On my team we purchase the shortest 3-wire connector possible for the connection we need to make, and we are incredibly careful to secure the wire and prevent it from moving (constant motion like swaying leads to wire fatigue, especially on thin high-AWG wires). Even then, we replace the wire every 2 seasons AND we've now been double-wiring. Fun fact is that the two RS485 ports on the Control/Expansion hubs are bi-directional and completely redundant, which means you can have two RS485 connections between the Control/Expansion hub and the connections are redundant (meaning if one fails, the other will still carry the signal). |
Hmm, maybe we will have to try the double wire trick also. USB is too flaky and I worry it will get disconnected during a match. Thanks for the tips. |
We had a similar issue last season, and the problem was the RS485 wire was running along with a bunch of motor wires, which was causing EMI and therefore connection dropouts. We just ran the wire elsewhere on the robot and things started working properly again. |
For the past couple days we've had our expansion hub disconnect and then have the robot become unresponsive. It comes back, but takes a few seconds for the robot to reboot.
We've pulled the logs and we see it marking the hub as unresponsive as well as telling us it's losing connection to the webcam. Any suggestions on what we can try as we have replaced the expansion hub and replaced the power cord. TIA
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