During the commissioning of OSN7500, an HARD_BAD alarm appears on the GSCC board, we try to cold reset the board, replace the board, switch to protection GSCC board, but the alarm persist .
after we add manually the MR2 board in slot 27, the HAR_BAD alarm disappear from GSCC board and the problem is solved.
when we browse the alarm on the GSCC board, we checked the alarm parameter as bellow picture, the parameter is 0X1B 0XFF 0XFF 0XFF 0XFF.
normally the first parameter is 0*1b indicates the board position that have problem if the GSCC board report the alarm.
so 0x1b = 1*16+b=16+b=16+11 in decimal=27,
in our design slot 27 contains MR2,when we check slot 27 in U2000 the slot is not added yet and doesn't appear because the MR2 is passive board.
during the commissioning, it's better to check in U2000 if all the boards are inserted and added in their correct position according to the design.