Rj45 null-modem cable (rs-232), Rj45 loopback plugs – Comtrol RocketPort INFINITY User Manual

Page 18

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18 - Connecting Serial Devices

RocketPort INFINITY User Guide: 2000465

Rev. E

Connecting Serial Devices

RJ45 Null-Modem
Cable (RS-232)

Use the following figure if you need
to build an RS-232 null-modem cable.
A null-modem cable is required for
connecting DTE devices.

RJ45 Null-Modem
Cable (RS-422 or RS-
485 Full-Duplex)

Use the following figure if you need to build
an RS-422 null-modem cable. A null-modem
cable is required for connecting DTE
devices.

Note: RS-422 pinouts are not standardized.

Each serial manufacturer uses
various pinouts. Please refer to the
documentation for the serial to
determine the pinouts for the signals in the previous picture.

RJ45 Straight-
Through Cable (RS-
232 or RS-485 Half-
Duplex)

Use straight-through cables to connect modems and other DTE devices. For
example, you can connect one end of a straight-through cable to COM2 on one
computer and the other end of the straight-through cable to a modem.

RJ45 Loopback
Plugs

RocketPort INFINITY models with RJ45 connectors are shipped with
a a single loopback plug (RS-232/422).

Wire the following pins together to build additional loopback plugs or
replace a missing RS-232/422 loopback plug:

Pins 4 to 5

Pins 1 to 8

Pins 2 to 6 to 7

Wire the following pins together for an RS-422 loopback plug:

Pins 4 to 5

Pins 1 to 8

TxD
RxD
RTS
CTS
DSR

GND

DCD
DTR

Signal

RxD
TxD
CTS
RTS
DTR

GND

DCD

DSR

Signal

DB9

2
3
8
7
4

5

1
6

Pins

DB25

3
2

4

7

8
6

Pins

RJ45

4
5
1
8
7

3

6
2

Pins

20

5

RocketPort

DTE Serial Device

TxD+
TxD-
RxD+

Signal

RJ45

1
4
8

Pins

RxD+
RxD-

Signal

RxD- 5

TxD+
TxD-

DTE Serial

Device

RocketPort

DB9

1
2
3
4
5

8

6
7

Pins

DCD
RxD
TxD

TRxD-

DTR
GND

CTS

DSR
RTS

TRxD+

Signal

DCD
RxD
TxD TRxD-
DTR
GND

CTS

DSR
RTS TRxD+

Signal

RI

9

RJ45

6
5
4
2
3

8

7
1

Pins

N/A

DB25

8
3
2
20
7

5

6
4

Pins

22

RI

RocketPort

DCE Serial Device

RS-232 RS-485HD

RS-232 RS-485HD

RS-232/422

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