B&B Electronics VESR9xx - Fiber Models - Manual - Manual (Page 20)

Setup and Connections
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data lines are differential pairs (A & B) in which the B line is positive relative to the A
line in the idle (mark) state. Ground provides a common mode reference.
When configured for 2-wire operation the connection supports one signal pair: Data
A (-) and Data B (+) signal channels using half-duplex operation. The data lines are
differential with the Data B line positive relative to Data A in the idle (mark) state.
Ground provides a common mode reference.
CONNECTING THE VESR901-X
The VESR901-x has one serial connection that supports RS-232, RS-422 and RS-485
(2- and 4-wire). The unit has two connectors: a DB-9M connector and a 5-position
terminal block.
If you select RS-232 mode when you configure the serial server, you must connect
the serial device to the serial server via a serial cable. The VESR901 is a DTE. If the
serial device is a DTE, use a null modem (cross-over) cable. If the serial device is a
DCE, use a straight-through cable.
If you select RS-422 mode, RS-485 2-wire mode, or RS-485 4-wire mode when you
configure the serial server, you must connect the serial device appropriately, via the
5-position terminal block.
Note: Refer to Appendix D for connector pinout information.
Figure 12. VESR901 Connections
CONNECTING THE VESR902T-X