Hi guys - building my first quad with PDB and I have a doubt on how to connect to the FC…
The PDB (Advanced Power Drives PDB360 X 8S 34V 360A for X Class Quad - Flying Tech) has 4 motor outputs, the Telemetry output and planning to power the FC with main bat pads (will be 6S or 8S batteries).
On the FC side ( https://store.tmotor.com/product/f7pro-flight-controller.html?srsltid=AfmBOoqrlQbpH0IOz6k0ForGot_oGHRi0lW3t8iL4022rKO2SriqNmHw ) - I can see the 4 motor pads, the power pads and a CUR and R4 pads on the connection socket.
What should I connect to the CURR and R4 pads of the FC? (one should take the telemetry - but what is the other one for?)
Thank you 
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Watched Bardwell building his XClass again on YT - R4 pads on the FC seems to be the Telemetry input in this case.
The FC CURR pad is I suppose for current sensing? Meaning I could power the FC with say 12V and give VBAT to the CURR pad?
I am planning to power the VTX through the FC (FC supports up to 8S and allows me to use the FC pit function) - hence giving the FC the full battery voltage. Am I right thinking I should just run another cable from the Battery pad to this CURR pad?
Been a while since I had PDBs between my external ESCs and my FC!
the CURR is a signal pad, so no VBAT on it. Since you don’t have a CURR pad on the PDB it seems, I would just NOT connect it. Instead you can use the telemetry from the ESC to get the current if you absolutely need it. IE connect the TLM from the PDB to one of the FC UARTs that you will use to receive the ESC telemetry and maintain the config in your FC firmware (betaflight or INAV or ARDU**** etc…).
Don’t forget to connect the signal / telemetry (and ground) wires from the external ESCs to the PDB (each of them).
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last point, I see there is vbat on the FC (as you stated 3-8S) - so the FC will derive automatically the voltage / current I would expect. they usually do.
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As @ORB_FPV rightly says DO NOT connect VBAT to CURR, you’ll damage the FC
Neither the FC or PDB have conventional current measurement circuitry so if you want current draw in the OSD (also applies to mAHr used) you need to use the TLM pad on the PDB to a UART on the FC, provided for on FC as TELE (RX4)
This will measure current from the ESC’s, see @ORB_FPV advice above 
HTH
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