Why does In System Source and Probe instance not have any signal? - Why does In System Source and Probe instance not have any signal? Description Due to problem in Quatus® Prime Software version 17.0 or earlier, you may not see any signal being connected in In System Source and Probe (ISSP) Graphical User Interface if either source or probe port width is set to 512. Resolution To work around this problem, you must reduce port width of source or probe to 511 or lower. This problem is scheduled to be fixed in a future release of Quartus Software Custom Fields values: ['novalue'] Troubleshooting FB: 490302; False ['novalue'] ['FPGA Dev Tools Quartus® Prime Software Pro'] 17.1 17.0 ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']