485LDRC-0812-1/3 2003 by B&B Electronics. All rights reserved. Models 485DRC and 485LDRC Industrial DIN Rail Mounted Optically Isolated RS-232 to RS-422/485 Converters With Surge Suppression Introduction The DIN Rail mountable Models 485DRC and 485LDRC optically isolate and convert unbalanced, full or half-duplex RS-232 signals to optically isolated, balanced, full or half-duplex RS-422 or RS-485 signals at baud rates up to 115.2 kbps. These units also surge suppress the RS-422/485 lines. They feature Send Data Control circuitry so no software control of handshake lines is required in RS-485 mode. LEDs The 485LDRC includes all the above features plus 3 LEDs: one indicating RS-485 Transmit Data, one for RS-485 Receive Data, and one for power. Description The 485DRC/485LDRC has screw down terminal blocks on the RS-232 side and the RS-422/RS-485 side. Transmit (TD), Receive (RD) and Ground are supported on the RS-232 side. The unit is powered by a supply voltage of 10 to 30VDC on the RS-232 side, useful where 24VDC is commonly found. Transmit Data A (-), Transmit Data B (+), Receive Data A (-), Receive Data B (+), and Ground are supported on the RS-422/RS-485 side. Communication features on the 485DRC/485LDRC are dipswitch selectable on the unit. RS-485 Mode with Send Data Control Send Data Control recognizes the first bit of data from the RS-232 side, enables the transmitter and disables the receiver. After the last bit of data is sent from the RS-232 side, the timeout waits one character length, then disables the transmitter and enables the receiver. The timeout can be selected with dipswitches or by changing the value of R11 (see Table 2). If the system requires the line to be turned around faster, i.e. the slave device starts responding before the transmitter of the 485DRC/485LDRC is disabled, R11 can be changed to meet the specific baud rate. Termination resistance can be selected with Switch 5 for high baud rates and long cable distances. See B&B Electronics RS-422/485 Application Note available on the website or by mail. Factory setting: 9600 baud. TYPICAL RS-422/485 4 WIRE Table 1. Typical Communication Setups A SETUP TD A - Switch 1 Switch 2 Switch 3 Switch 4 (TERMINAL BLOCK G) R Rt B TX Enable RX Enable 2/4 Wire 2/4 Wire TD B + TX (TERMINAL BLOCK H) RS-485 2-Wire Mode ON ON ON ON ENABLE RX (half-duplex) A RD A - RS-485 4-Wire Mode ON OFF OFF OFF (TERMINAL BLOCK K) Rt B G (full-duplex) RD B + (TERMINAL BLOCK L) RS-422 Mode OFF OFF OFF OFF (full-duplex) GND (TERMINAL BLOCK M) G Generator 485DRC/485LDRC R Receiver Table 2. Baud Rate Selection Circuit ground Switch Switch Switch R11 Time (ms) TYPICAL TWO-WIRE RS-485 SETUP 6 7 8 A 1200 OFF OFF OFF 8.33 820k DATA - (TERMINAL BLOCK G) 2400 OFF OFF ON Not Used 4.16 R Rt B DATA + 4800 OFF ON OFF Not Used 2.08 TX (TERMINAL BLOCK H) 9600 ON OFF OFF Not Used 1.04 A RX 19200 ON ON ON Not Used .580 GND G Generator (TERMINAL BLOCK M) G 38400 OFF OFF OFF 27k .260 B R Receiver 57600 OFF OFF OFF 16k .176 Circuit ground 115200 OFF OFF OFF .0868 8.2k 485DRC/485LDRC In a two-wire setup, switches 3 & 4 should be ON, making terminal block (G) the Data () line and terminal block (H) the Data (+) line. www.bb-elec.com orders bb-elec.com support bb-elec.com International Office: 707 Dayton Road PO Box 1040 Ottawa, IL 61350 USA 815-433-5100 Fax 433-5104 European Office: Westlink Commercial Park Oranmore Co. Galway Ireland +353 91 792444 Fax +353 91 792445 PRODUCT INFORMATION B&B ELECTRONICS 485LDRC-0812-2/3 2003 by B&B Electronics. All rights reserved. Terminal Block Configuration RS-232 (D) TD (input) (A) RD (output) (B) SIG. GND (F) +10 to 30VDC (C) PWR. GND RS-422/485 TDA (G) Tx inverted or (-) (output) RDA (K) Rx inverted or (-) (input) TDB (H) Tx non-inverted or (+) (output) RDB (L) Rx non-inverted or (+) (input) ISO. GND (M) Isolated RS-422/485 Signal Ground/Common Switch Settings (UP = ON) 1 - Tx Enable (On for 485 mode. Off for 422 mode.) 2 - Rx Enable (On for 2-wire 485 mode. Off for 4-wire 485 and 422 mode.) 3 - 2/4 Wire (On for 2-wire/half duplex. Off for 4-wire full duplex.) 4 - 2/4 Wire (On for 2-wire. Off for 4-wire.) 5 - Termination Resistors (On for termination. Off for no termination.) 6 - 9600 Baud (On for 9600, Off for others. See Table 2 for additional baud rates.) 7 - 4800 Baud (On for 4800, Off for others. See Table 2 for additional baud rates.) 8 - 2400 Baud (On for 2400, Off for others. See Table 2 for additional baud rates.) www.bb-elec.com orders bb-elec.com support bb-elec.com International Office: 707 Dayton Road PO Box 1040 Ottawa, IL 61350 USA 815-433-5100 Fax 433-5104 European Office: Westlink Commercial Park Oranmore Co. Galway Ireland +353 91 792444 Fax +353 91 792445 PRODUCT INFORMATION B&B ELECTRONICS