Connections between Cube and Carrier board

what is the difference between VDD_SERVO and VDD_SERVOIN in cube 80 pin connector. Also, I am not able to understand how their corresponding pins (pin 53 and pin 9 respectively) are connected to the carrier board.

VDD_SERVO connect to the 5V pin of the servos outputs and is used to monitor the voltage of the servos rail
VDD_SERVO_IN is connected to the PSM but I don’t remember the function

Hi @Julien . Thanks for the reply. As i understand VDD_SERVO is an input pin for the cube to monitor the servo rail voltage. Then my question is where is VDD_SERVO getting input voltage from as it is also acting as the 5V output pin.

VDD_SERVO (pin 53) is an input used to monitor the voltage of the servo rail. It du not provide power.
All positive servo pins are connected together on most of the carrier boards, so in case you connect a Ubec to one of them, the VDD_SERVO will monitor this power supply.
I don’t remember the voltage limit, @Philip ?

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Thanks Julien. I think I understood the VDD_SERVO connection. Also, the voltage limit is 10.5 V max i guess for the servo rail.
However, I am still not able to understand the VDD_SERVO_IN connection. In the manual it says that it is used as a backup for I/O but from where is it getting the voltage input and what is the limit of that voltage? Are the VDD_SERVO and VDD_SERVO_IN both connected to the positive of servo rail?
I would request @philip to help too.

The VDD_SERVO_IN connect to the PSM (Power Selection Module)

Thanks Julien. Thank you for your time.

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Hi @Julien, just one more question. Please help me clear this doubt.
Is the positive of the servo rail connected to the PSM (which is then used to provide VDD_SERVO_IN to the cube as failsafe for I/O).

No, the positive pins of servo rail are just connected together (to allow using one to power all others) and to VDD_SERVO (to monitor)

Okay thanks for clearing that out. But then what exactly is VDD_SERVO_IN.
In the documentation it says that it is “Power for last resort I/O failsafe”. So where is this power coming from. I initially thought that its power is coming from servo power with some filtering via the PSM.