RS-232C to RS-485 converter C-285B

RS232/RS485 converter C285IA

C-285B is a half-duplex galvanically isolated RS-232C – RS-485 converter. It is used in industrial applications, when the need of galvanically isolated interfaces in industrial 'noisy' environment is critical. Also, standard RS-232 is used to maximum 100 feet cable length and is a point-to-point type of communication. RS-485 is multi-device net and is used to cable length up to 4000 feet. This converter can work either with external control of RTS or automatic direction control (only TxD and RxD are connected). Power supply can be 220VAC or 12/24VDC (must be clear when ordered). The mounting is made on a standard М36 DIN-rail.

user manual


Main technical parameters of C285B

max number of devices in 485 network 250
speed 300-115200 bps
maximum distance in 485 network 1200m
power supply 100-250 VAC (140-350 VDC) or 12/24 VDC
power consumption < 3 W
isolation voltage > 600 VAC, > 1400 VDC
work temperature from -10° C to +50° C
storage temperature from -50° C to +90° C
dimensions (H/W/D) 86/70/57 mm
protection class IP30
own weight 120 g

Normal mode of operation

C-285B starts immediate work after providing power supply. The control of transmitting/receiving data can be done by RTS line of the device with RS-232 interface (CTS line of C-285B) or automatic (if no RTS line is provided). External RTS has priority against automatic direction control. Baud rate from 300 to 115200 bps can be achieved with automatic RTS. There are two DIP-switches inside C-285B, which controls delay time to clear the line. User can select 4 different delays - time after last byte transmitted when C-285B enters receive mode (RTS = 0).

Mounting and electrical wiring