... -S803VCS/R ,3 channel video signal transmit by one coaxial cable video multiplexer with RS485 usded in CCTV Maintenance SD-S803VCS ... +1CH negative data1,as project demand,the device is optimized interface,and is convenient for installment with mini volume;2,Transmit ... control signal optionally through selector switch;3,RS 485 control interface can be driven by special chip with 15Kv anti-stastic ...