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Building Custom Cables
This section contains cabling information and how to build your own
custom cables for RocketPort controllers. To go to any of the following
topics, merely click on the topic:
• Building Custom Cables
• Shielding Cables
• Using Modular Connectors
• DTE to DCE Straight-Through Cables
• DTE to DTE Null-Modem Cables
• DTE to DTE Data-Only Null Modem Cables
• DTE to DTE Control Loop-Back Cables
• RS-422 DTE to DTE Cables
• Pinouts for DB25 Connectors
• Pinouts for DB9 Connectors
• Pinouts for RJ45 Connectors
• Pinouts for RJ11 Connectors
Building Custom Cables
Use this subsection if you want to build customized cables for the
Comtrol RocketPort controllers.
Usually you can buy the correct cables from distributors and electronics
stores for your controller. In some cases, your peripheral equipment
may need custom cables.
Check your equipment to understand what kind of cable to use, Data
Terminal Equipment (DTE) or Data Communications Equipment
(DCE). All Comtrol serial connectors are configured as DTE.
Building Custom Cables 1
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Building Custom Cables
DTR
20
DTR
4
20
2
1 4
Shielding Cables
The controller falls within the limits for a Class A computing device
established by the FCC. To comply with these limits, the serial cables
used to connect the controller to external devices should be shielded.
The shield should be connected to a metal or metallized connector
shroud on each end of the cable.
Using Modular Connectors
The RJ45 and RJ11 connector is similar to the phone-jack type of
connector. Both the connector and cable are easily available from your
distributor or any electronics store. You may want to connect your
peripherals using a D-shell type of connector to an RJ45 interface with
a straight-through cable and an adapter that you build.
DTE to DCE Straight-Through Cables
The following figure shows the most common types of DTE to DCE
cables. This configuration also referred to as a modem cable, because
it works with most modems.
Note: If you have a DTE to DCE interface but are uncertain as to what
signals are needed, you can use a full 25-wire cable. This cable
is constructed like the following cable example, but in addition,
all of the remaining pins are connected
RocketPort Connector
DB25
RJ45
Signal
Name
TxD
RxD
RTS
CTS
DSR
GND
DCD
Pins
2
3
4
5
6
7
8
Pins
4
5
1
8
7
3
6
RJ11 DB9
Pins Pins
3 3
4 2
N/A 7
N/A 8
N/A 6
2 5
5 1
Remote Connector
DB9
DB25
Pins
2
3
4
5
6
7
8
Signal
Name
TxD
RxD
RTS
CTS
DSR
GND
DCD
Pins
3
2
7
8
6
5
1
DTE to DTE Null-Modem Cables
If you need RTS-CTS/DTR-DSR hardware flow control, you can
probably use the following figure. Some equipment may require
different connections for the control signals.
2 Building Custom Cables
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Building Custom Cables
GND
7
GND
5
7
3
2 5
GND
7
GND
5
7
3
2 5
GND
7
GND
5
7
3
2 5
RocketPort Connector
Signal
Name
TxD
RxD
RTS
CTS
DSR
DCD
DTR
DB25
Pins
2
3
4
5
6
8
20
RJ45
Pins
4
5
1
8
7
6
2
RJ11 DB9
Pins Pins
3 3
4 2
N/A 7
N/A 8
N/A 6
5 1
1 4
Remote Connector
DB9
DB25
Pins
3
2
5
4
20
8
6
Signal
Name
RxD
TxD
CTS
RTS
DTR
DCD
DSR
Pins
2
3
8
7
4
1
6
DTE to DTE Data-Only Null Modem Cables
If no hardware flow is needed, use the following figure. With a 3-wire
cable, software flow control must be used, if control is needed.
RocketPort Connector
Signal
Name
TxD
RxD
DB25
RJ45
RJ11 DB9
Pins
Pins
2
3
Pins Pins
4
3 3
5
4 2
Remote Connector
DB9
DB25
Pins
3
2
Signal
Name
RxD
TxD
Pins
2
3
DTE to DTE Control Loop-Back Cables
Some equipment may not require hardware handshaking, but may
require that certain control signals are active before sending data.
RocketPort Connector
Signal
Name
Building Custom Cables 3
TxD
RxD
RTS
CTS
DSR
DCD
DTR
DB25
Pins
2
3
4
5
6
8
20
RJ45
Pins
4
5
1
8
7
6
2
RJ11 DB9
Pins Pins
3 3
4 2
N/A 7
N/A 8
N/A 6
5 1
1 4
Remote Connector
DB9
DB25
Pins
3
2
4
5
6
8
20
Signal
Name
RxD
TxD
RTS
CTS
DSR
DCD
DTR
Pins
2
3
7
8
6
1
4
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Building Custom Cables
GND 7 GND
RS-422 DTE to DTE Cables
Most RS-422 communication links usually do not use hardware
handshaking or signal ground lines. The following figure shows
twisted-pair transmission lines that work in most cases.
RocketPort Connector
Signal
Name
TxD+
TxD- 25
RxD+
RxD-
DB25
Pins
19
15
17
Remote Connector
Signal
Name
RxD+
RxD-
TxD+
TxD-
Pinouts for DB25 Connectors
Use the following table and figure for pinout information for all
interface boxes and DB25 connectors on the Quadcable and Octacable.
Note: The Quadcable, Octacable, and the RJ45 Rack Mount do not
support RS-422 mode.
Table 1. DB25 Connector Pinouts
Pin RS-232 Signal RS-422 Signal
1 Not used Not used
2 TxD Not used*
3 RxD Not used*
4
5
6
7 Signal ground Signal ground*
8
9 through 14 Not used Not used
15 Not used RxD+
16 Not used Not used
17 Not used RxD18 Not used Not used
19 Not used TxD+
RTS
CTS
DSR
DCD
Not used*
Not used*
Not used*
Not used*
4 Pinouts for DB25 Connectors
Page 5
Table 1. DB25 Connector Pinouts (Continued)
Pin RS-232 Signal RS-422 Signal
20
DTR
21 through 24 Not used Not used
25 Not used TxD-
* All RS-232 signals are present in RS-422 mode.
Building Custom Cables
Not used*
DB25 Female
Pin 13 Pin 1
Pin 25 Pin 14
DB25 Male
Pin 1 Pin 13
Pin 14 Pin 25
Pinouts for DB9 Connectors
Use the following table and figure for pinout information for the DB9
connectors on the Quad/Octacable.
Table 2. DB9 Connector Pinouts
Pin RS-232 Signal
1 CD
2 RxD
3 TxD
4
5 Signal ground
6
7 RTS
8
9 Not used
DTR
DSR
CTS
DB9 Male
Pin 1
Pin 6
Pinouts for DB9 Connectors 5
Pin5
Pin 9
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Building Custom Cables
Pinouts for RJ45 Connectors
Use the following table and figure for pinout information for the RJ45
connectors on the RocketPort 4J.
4J/RJ45
1 8
Pin 1
Plug
Top View
Cable
Receptacle
Table 3. RJ45 Connector Pinouts
Pin
RS-232 Signals
1
2
3
4J/RJ45
RTS
DTR
GND
4 TxD
5 RxD
6
7
8
DCD
DSR
CTS
Pin 1
6 Pinouts for RJ45 Connectors
Page 7
Building Custom Cables
Pinouts for RJ11 Connectors
Use the following table and figure for pinout information for the RJ11
connectors on the RocketPort 8J.
8J/RJ11
1
Plug
Top View
Cable
6
Pin 1
Pin 1
Receptacle
Table 4. RJ11 Connector Pinouts
Pin
RS-232 Signals
8J/RJ11
1 DTR
2 GND
3 TxD
4 RxD
5 DCD
6 Not Connected
7 Not Applicable
8 Not Applicable
•
Pinouts for RJ11 Connectors 7
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