The BLACK BOX® Universal RS-232 to RS-422/485 Converter with Opto-Isolation isolates and converts RS-232 signals into RS-422/RS-485 signals and vice versa. Unlike other converters external software is not required to control data flow. The RS-232 input is wired for DCE through a DB9 female connector and RS-422/RS-485 signals are interfaced through a removable terminal block. To supply external power to the terminal block you need our 120-VAC/12-VDC Wallmount Power Supply (PS1003).

For RS-232 the connection requires RD TD and Signal Ground.

In RS-422 mode the driver is always enabled for full-duplex communications. A twisted pair is required for transmit and a twisted pair is also required to receive. A ground reference wire is also needed. Switch settings are Switch 1: RS-422; Switch 2: Echo On; Switches 3 and 4: 4 Wire.

In both RS-485 modes the RS-485 driver is automatically enabled during each space state by the presence of an RS-232 signal. When the RS-232 data is in a mark or idle state the RS-485 driver is disabled and the RS-485 data lines are held in a mark state by the bias provided by a 4.7-ohm resistor; the value of this resistor may need to be changed depending on the termination you use.

To connect to several RS-485 devices with minimal wire select the unit's 2-wire half-duplex RS-485 mode. When data is requested the addressed device transmits and then reverts back to receive status. Switch settings for this mode are Switch 1: RS-485; Switch 2: Echo Off; Switches 3 and 4: 2 Wire.

For 4-wire master/slave circuits select the unit's 4-wire full-duplex RS-485 mode. In this mode addressed devices can receive data while transmitting data from a previous request. When used as a master in a single-master system Switch 1 may be selected because the unit is the only transmitter in the system. When used as an RS-485 slave the RS-232 device must provide addressability. Biasing in a master/slave system is provided by the end-of-line slave. Switch settings for this mode are Switch 1: RS-485; Switch 2: Echo On; Switches 3 and 4: 4 Wire.

Features:

• Features 2000-VAC isolation
• Selectable RS-422 operation
• Select RS-485 for 2-wire half-duplex or 4-wire full-duplex
• Auto RS-485 driver control.