Document No. 422OPINA4898 - pg. 1/2
B&B Electronics December 1998
This product designed and manufactured in USA of domestic and imported parts by
Optically Isolated RS-232 to RS-422/485
Model 422OPINA
Description:
The 422OPINA converts unbalanced, full-duplex RS-232 signals to
balanced, full or half-duplex RS-422 or RS-485 signals. The following
signals are supported: TD on pin 2, RD on pin 3, RTS on pin 4, and CTS
on pin 5.
Specifications:
Signals Supported:
TD, RD, RTS, & CTS
Dimensions:
Approximately 2.75" x 4.60" x 0.68"
Data Rate:
Up to 19.2K baud
Connectors:
RS-232:
DB25S (female) and Terminal Blocks
RS-422/485:
Terminal Blocks
Isolation:
2500VAC optical isolation of data signals and ground
Power Requirements:
RS-232 Side:
From +12VDC to +18VDC at 40mA maximum. Apply to TB1 at +12VDC and GND.
RS-422/485 Side:
From +12VDC to +18VDC at 160mA maximum. Apply to TB2 at I+12VDC and IGND.
Configuration:
In RS-485 mode, the driver enable is controlled with the RTS line from the RS-232 port. We refer to this as RTS control. With
jumper JP3 in the 485 position the driver is enabled when the RTS handshaking line is asserted by your software. You must then
disassert RTS in order to disable the RS-485 driver. With jumper JP4 in the 485 position, the receiver will be disabled while the driver
is enabled. Jumper JP4 can be put in the 422 position for constant enable of the receiver.
In RS-422 mode, jumpers JP3 & JP4 should be in the 422 position. In 422 mode the driver and receiver will always be enabled
for full-duplex communications.
There are 4 two-color LEDs for monitoring the supported signals (red = neg. voltage, green = pos. voltage).
The board layout has an option for termination resistors (approx. 120 ohm): R9 for the 422/485 RD lines, and R31 for the 422
CTS lines.
The RS-422 Standard recommends 24AWG copper conductor, twisted-pair telephone cable with a shunt capacitance of 16pf per
foot up to 4000 feet.
The 232 and 485 power sources must be isolated in order to keep the optical isolation. Power for the 232 side will be connected
to TB1 at +12VDC and GND. The 485 power connects to TB2 at I+12VDC and IGND.
Connect the 422/485 signals to TB2 as follows:
2-WIRE MODE
422OPINA: 485 Device:
TD(A) & RD(A) ----------- (A) or (-)
TD(B) & RD(B) ----------- (B) or (+)
If used: RTS(A) & CTS(A) ------- (A) or (-)
RTS(B) & CTS(B) -------- (B) or (+)
4-WIRE MODE
422OPINA: 422/485 Device:
TD(A) -------- Receive Data (A) or (-)
TD(B) -------- Receive Data (B) or (+)
RD(A) --------Transmit Data (A) or (-)
RD(B) --------Transmit Data (B) or (+)
If used: RTS(A) ------ Clear To Send (A) or (-)
RTS(B) ------ Clear To Send (B) or (+)
CTS(A) ------ Request To Send (A) or (-)
CTS(B) ------ Request To Send (B) or (+)
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