TOPEX Bytton (HSPA+ / LTE)
ByttonLTE(full)_genericUsermanual_sw306FAS_revN.1.docx
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Connecting the serial cable(s) :
In case of R&S Topex equipments fitted with serial interfaces, you may connect legacy devices fitted with
serial interfaces to the Bytton rICR outer, using special serial cables.
Serial connectors
Bytton features on the front panel one or two RJ-45 connectors for the serial
interfaces. These connector don’t have embedded LED indicators, and the
metallic casing is tied to the electrical ground.
This is why special connection cables must be used, which feature a RJ-45
male connector towards the Bytton LTE and a DB-9 female or DB-25 male or
female connector towards the legacy equipment (type DTE or DCE).
Software configuration
You can establish from the Web configuration interface how your data packet will be is sent over the
serial interfaces: with 7 or 8 bit words, with or without start, stop, and parity bits, what kind of flow control
shall be used (X-On/X-Off, none or hardware), and of course the transfer speed. But you cannot select
from the Web interface if the serial link is RS-232 or EIA-485, this is established at the factory!
Type of serial link
When you order the Bytton LTE equipment with serial interfaces, you must specify, whether the serial
interface shall be RS-232 or RS-485.
The selection is done in the manufacturing process, the type cannot
be changed via Web interface for configuration or by means of jumpers
.
This choice determines the voltage level and the pin assignment on the RJ-45 connectors.
RS-232
RS-232 connection in not of the minimal "3-wire" type, consisting only of transmit data, receive data, and
ground, but includes also hardware flow control: it also uses the RTS and CTS lines ( 5-wire version).
RTS is “ Request To Send”, issued from the DTE towards the DCE, telling it to be prepared, while CTS is
“Clear To Send”, issued by the DCE to show that it is ready to accept data.
RS-485
When you specify the variant with serial interfaces implementing the EIA-485 standard, you get an
interface with multi-drop capability, which may be used effectively over long distances and in electrically
noisy environments. The RS-485 variant is often used in industrial environments and similar field
applications.
Bytton LTE implements the full-duplex, four wires mode of operation. The signal ground is also available
on the connector, although it is not absolutely required.
The connector has a termination resistor connected across the two wires of each pair, to eliminate
reflections and two powered resistors to bias the lines apart when the lines are not being driven.
RJ-45 Serial Connector Pinout
PIN Number
RS-232
RS-485
1
RTS
TX
2
-TX
3
TX
RX
4
-RX
5
GND
GND
6
RX
7
8
CTS
The other pins of the serial connectors are not currently used. The metallic casing of the connectors is tied
to the signal ground.
