Returns 2 bytes wide answer to the provided LDI command.
FRC user-data has the following format:
UserData[0] 0x4A (equals to the PNUM).
UserData[1…2] Command to send and to return the answer of. See CMD #n parameter at the DPA request of Send LDI Commands.
UserData[3] Reserved. Must equal to 0.
Returned 2 bytes wide FRC value has the same format as the Answer #n parameter at the DPA response of Send LDI Commands.