Referring to UM1052, chapter 14.
It says that register s 0x3F and 0x40 are available to read using the get register command frame over UART.
I have most of the other registers up and running, so the problem is not with UART com.
I get the response bach from the motor control board with error code 0x03 "Read not allowed. The value cannot be read".
Anyone having the same problem. I see where in the code to fix this, but I guess it should be reported as a bug.