So far, the OpenRB-150 had been working well for me - see this post:
https://forum.robotis.com/t/first-look-at-openrb-150/1059
I was using XL-320s (7.5V) or XL-330s (5 V) mostly and I powered everything via the Terminal Block with the Jumper set on the VIN(DXL) side. And everything worked fine.
Recently, I switched to using AX-12/18 and XL-430, i.e., DXLs that need 12 V, then I found a peculiar problem when I used the typical 12 V Power Supply that comes with the typical ROBOTIS Kit:
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When this 12 V PS is plugged into an EMPTY OpenRB-150, the Power LED on the OpenRB-150 turns on first, and then 1-2 second later, the DXL LED on the OpenRB-150 turns on next, and Windows sounds out with a ding telling me that the USB C Com Port is connected OK. And ARDUINO can connect to this COM Port OK also.
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However, if I have some DXLs (AX-12 or XL-430) connected to the OpenRB-150 before I turn on the 12 V PS like in the previous paragraph, then the sequence of events is like this: OpenRB-150’s Power LED comes on, but DXL LED does not come on, and Windows does not connect to the USB C Com Port and consequently Arduino also does not see this COM Port and of course Arduino then does not work for me.
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I have a Variable PS 3V-12V that I can use instead of the ROBOTIS fixed-12V PS, so I did some more experiments, and this is what I found:
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If an XL-430 is used, then I cannot go higher than 11 V for the power on sequence to work out like in Paragraph 1) - And everything works fine again, from Windows to Arduino. This means that a LiPo battery pack can do the job for XL-430s.
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If an AX-12 is used, then I cannot go higher than 10 V for the power on sequence to work out like in Paragraph 1) - And everything works fine again, from Windows to Arduino.
- I also found a work-around solution:
- I can use the ROBOTIS fixed 12 V PS to power the DXLs separately from the OpenRB-150 which I can power with a separate PS at 5 V for example. Of course, the X3P cable , that connects the DXL bus on the OpenRB-150 to the actual network of DXLs (AX-12s or XL-430s), needs to have its VDD wire severed as the OpenRB-150 only needs the GND and DATA wires to control the DXLs in this configuration.
I have two OpenRB-150s that act like described above, so maybe I am just unlucky or maybe ROBOTIS needs to look into this issue further - some kind of interaction between the USB C and the VIN(DXL) option, as the OpenRB-150 specs say that it can function between 3.7 V and 12.6 V, but it really does not (at least from my experiences). 
