The product page of 功能扩展软件 "WV-SPN6R481" from the Panasonic Security System. You can download features, manuals and firmware, specification sheet and more for WV-SPN6R481 here.
WV-SPN6R481 Key Feature - Panasonic安防监控系统 - 产品
RS-485 Output unit
This is the RS485 Output unit for the WV-SPN6 series.
It will be referred to as RS485 Output unit from here on.