The MR3-M200P-12-240VAC and the rest of the MR3 series of photoelectric sensors has gone obsolete. According to their website and seen on the snip below, Panasonic recommends the EQ-500 series as replacements. Please review the datasheets to ensure the alternative will work for your application.
Discontinued Part Numbers
MR3-M100A-DC12-24V
MR3-M100AT-DC12-24V
MR3-M200A-DC12-24V
MR3-M200AT-DC12-24V
MR3-M100P-12-240VCE
MR3-M100PT-12-240VCE
MR3-M200P-12-240VCE
MR3-M200PT-12-240VCE