USB to Serial Converters Manual
Version 2.0
Document Reference No.: CP_000032 Clearance No.: CP#022
Copyright © Connective Peripherals Pte Ltd
24
ES-U-xxxx-x converters have four jumpers to select biasing on Tx+, Tx-, Rx+ and Rx-. Section 5 describes
these in more detail. For half-duplex RS-485, only the jumpers for Rx biasing (
Pull up of Rx+
Pull down
of Rx-
) should be fitted. The jumpers for Tx biasing (
Pull up of Tx+
and
Pull down of Tx-
)
should not be
fitted as this would provide two biasing resistors per line.
5.2
ES-U-2x01B / ES-U-2x01C Adapters (Plastic Enclosure)
This section applies to the following adapters:
•
ES-U-2001B
(see note below)
•
ES-U-2001C
(see note below)
•
ES-U-2101B
(see note below)
•
ES-U-2101C
(see note below)
Note:
This section applies
only
to revision B and C units which have the part numbers listed above. For
the original ES-U-2001 and ES-U-2101, please refer to version 1.4 of this guide which is available from the
Connective Peripherals website.
This section does not apply to ES-U-2xxx-M (metal case) adapters. Please see sections 5.3 and 5.4 for
these products.
See the General Notes and Warnings on page 23 before changing settings or opening the cover.
The jumpers should be set to select the correct serial mode before connecting the converter to
your RS-422/RS-485 serial bus.
DIP Switch Settings
On the inside of the unit, there are three DIP switches, which are used to select the required serial mode
(RS-422 or RS-485).
Operation Mode
S1
S2
S3
RS-422
4 Wire with handshaking
ON
ON
ON
RS-485
Full Duplex (4 wire)
OFF
ON
ON
Half Duplex (2 wire) with Echo
OFF
OFF
ON
Half Duplex (2 wire) without Echo
OFF
OFF
OFF
Table 2 - RS-422 & RS-485 Mode Configuration
