The 6AV3505-1FB12 is the Siemens OP5/A2 Operator Panel.
The 6AV3505-1FB12 is the Siemens OP5/A2 Operator Panel. It features a 4-line display with 20 characters per line and supports interfaces like TTY/V.24 and RS422/485/MPI/PPI/SINEC L2-DP. This panel was designed for industrial automation applications but has been discontinued since October 1, 2010. Siemens recommends the OP7 as a replacement.