RS485 lines can typically run hundreds of metres or more. One side effect of such long line lengths can be harmful transients and ground-loop currents which can introduce errors or disrupt communications or even damage the host.

The CE-0019D electrically isolates RS485 buses from other RS485 buses through an optical isolation barrier rated at over 3,000 volts. Not only does this prevent harmful voltages being coupled through to the each side but it also isolates grounds from side which otherwise could afffect the inherent common-mode voltage rejection, a problem on many balanced networks.

RS-485 networks are half-duplex and normally require a transmit enable signal, something akin to the “press to talk” on 2-way radios. Cescom's range of converters feature Automatic Transmit Enable (ATE) processing based upon precise timing related to each character sent so that the transmit enable automatically engages on the reception of a character from either side. This transmit enable stays asserted for the length of the character and deasserts if no other characters have been detected within 1.5 bits after the stop bit.

This makes the CE-0019D the perfect candiate for RS-485 networks which require isolation and repeater functions to improve the range and reliability of the network.

Current

55ma @12VDC, 24ma @30VDC

Physical

80mm x 26mm x 100mm (HWD)

TX/RX Control

ATE

Weight

200 grams (approx)

ATE turnon

1us max

Weight

200g

ATE turnoff

1.5 character bits or 1ms

Case Material

Polyamide 6.6

Indicators

TxData, RxData, Power

Environment

0 to +75'C operating

Standards

EIA/RS485; AS/NZS-3548 EMI/EMC; C Tick compliant

OPERATION

CONNECTIONS

RS-485 to RS-485

In the idle state both sides of the repeater are tristated and as such are ready to receive. Whichever side receives data first will be the one to switch the other side to transmit until the receiving side stops receiving data within the ATE timeout period in which it will return to the idle state.