The PL Readback function through the DevC interface is supported only after the PL has been configured.
Minor. If a PL Readback operation is performed before the PL is configured, then the readback values are undefined. Examples of scenarios in which the readback operation is desired are SEU Detection, reading of the PL IDCODE, and partial reconfiguration.
Configure the PL before attempting PL Readback operations through the PCAP.
Systems wanting the PS to read PL configuration registers or readback PL configuration design data through the DevC interface.
Device Revision(s) Affected:
Refer to (Xilinx Answer 47916) - Zynq-7000 SoC Silicon Revision Differences.