Why does my source get set to 0 unexpectedly in In-System Sources and Probes? - Why does my source get set to 0 unexpectedly in In-System Sources and Probes? Description Due to the problem in the Quartus® II software versions 12.1 and earlier, In-System Sources and Probes may unexpectedly set your source to 0. This may occur in either of the following situations: Opening the In-System Sources and Probes Editor without having your Quartus II project open first On the In-System Sources and Probes Editor Edit menu, selecting Recreate Instances From JTAG Device When this error occurs, you may see the following message in the System message tab: Info (261000): write_source_data -instance_index 0 -value 0 -value_in_hex Resolution To work around this problem, perform either of the following actions: Open the Quartus II project before opening the In-System Sources and Probes Editor Save the setup in a Sources and Probes File ( .spf ), and load the Editor by opening that .spf This problem is scheduled to be fixed in a future release of the Quartus II software. Custom Fields values: ['novalue'] Troubleshooting novalue False ['novalue'] ['FPGA Dev Tools Quartus II Software'] novalue 10.0 ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']