Accessories

Model 485BAT3 features power versatility, making it perfect for field testing solutions. It converts unbalanced RS-232 signals to balanced RS-422 or RS-485 signals. RS-485 is an enhanced version of the RS-422 standard, allowing multiple drivers and receivers on a two-wire system.

Model BB-422LCOR, non-isolated serial converter, converts unbalanced RS-232 signals to balanced voltage digital interface with data rates up to 90K bits per second on cable lengths of 1200 meters (4000 ft). Ten receivers can be connected to any one driver for use in multi-drop systems.

The RS-232 port is a female DB25 connector with pins 2 (TD input) and 3 (RD output) supported. Protective Ground (pin 1) and Signal Ground (pin 7) are also connected. The RS- 422 port is a male DB25 connector with Send Data outputs on pins 2 and 14, and Receive Data inputs on pins 5 and 17. Protective Ground (pin 1) and Signal Ground (pin 7) are connected through to the RS-232 connector.

Interconnection of the converter with another RS-422 device:

The polarity of the two RS-422 lines must be correct. With no data being sent, the RS-232 line should be negative and the RS-422 "A" terminal should be negative with respect to the "B" terminal.

The wire recommended in the RS-422 Standard is number 24 AWG copper conductor, twisted-pair telephone cable with a shunt capacitance of 16 pF per foot.

For long runs and/or high data rates, it is recommended that the wires be terminated with a resistor at the receive end. The twisted pair usually used has an impedance of about 100 Ohms, therefore a 100 Ohm resistor is normally used for termination. The RS-422 side of the converter requires more power as the transmission line is increased and termination resistor value is reduced, therefore it may be necessary to use a termination resistor that is larger than 100 Ohms.

The RS-422 driver has the ability to drive ten RS-422 receivers connected in parallel. A system of multiple receivers may require some experimentation with location and size of termination resistors, line lengths, grounding, etc.

This RS-232 to RS-422 converter converts unbalanced RS-232 signals to balanced RS-422 signals. The power used for this converter is derived from the transmit data line (pin 2) and the handshake control lines (pins 4, 5, 6, 8, and 20). The converter can derive power from these lines when they are in the positive or negative voltage state. This permits the converter to be used in applications without any regard to software control of the handshake lines. If no handshake lines are available and all power must be derived from the transmit data line, the converter can drive limited cable lengths. A guide for this condition would be to drive only several hundred feet of transmission line and not to terminate the transmission line with a resistor of less than 1000 ohms. When more handshake lines are available longer lengths of cable can be driven. This converter has been tested at 115.2k baud with 4000 feet of cable. For applications where handshake lines are not available and long cable runs are involved, an external power supply can be connected to the male connector on the RS-422 side of the converter on pins 12 (Gnd) and 25 (+12).

The 422LP9R is a port - powered two - channel RS - 232 to RS - 422 converter. It converts TD and RD RS - 232 lines to balanced RS - 422 signals. The unit is powered from the RS - 232 handshake lines DTR an d RTS. One of these handshake lines must be asserted (high) in order to power the unit (See Table 1). The RS - 422 driver is enabled when RTS is asserted. Therefore, RTS must be asserted in order to transmit data. The RS - 422 receiver is always enabled. If DT R is always asserted and the RTS is used to control the driver, the 422LP9R can be used as a RS - 232 to RS - 485 4 - wire converter. To insure reception, it is recommended that DTR is asserted.

In order to maximize the amount of power available to the RS - 422 d river, the RS - 232 handshake lines are not looped back (tied together). As a result the following handshake lines will appear as disasserted (low): CTS, DCD, and DSR. Care should be taken to insure that any software being used doesn't require any of these handshake lines be asserted. If existing software requires any of the handshake lines to be asserted, you can loop back the required handshake lines in your cable.

• IEEE-61850-3
• IEEE 1613
• -40 to 85°C Operating Temperature
• Rugged IP30 Metal Panel Mount Case
• 50G Shock, 4G Vibration
• 2kV Triple Isolation
• 10 to 48 VDC Input Power