DIGI PIN ASSIGNMENTS
Digi DB-9 Connector Pin Assignments
Signal Description DTE Use Pin #
GND Chassis Ground N/A Shell
DCD Data Carrier Detect Input 1
RxD Received Data Input 2
TxD Transmitted Data Output 3
DTR Data Terminal Ready Output 4
SG Signal Ground Reference 5
DSR Data Set Ready Input 6
RTS Request to Send Output 7
CTS Clear to Send Input 8
RI Ring Indicator Input 9
Note that GND and SG on the DB-9 are connected within the USB module.
Digi DB-25 Connector Pin Assignments
Signal Description DTE Use Pin #
GND Chassis Ground N/A Shell
TxD Transmitted Data Output 2
RxD Received Data Input 3
RTS Request to Send Output 4
CTS Clear to Send Input 5
DSR Data Set Ready Input 6
SG Signal Ground Reference 7
DCD Data Carrier Detect Input 8
DTR Data Terminal Ready Output 20
RI Ring Indicator Input 22
CABLE WIRING
This section contains the following topics:
DB-9 to Modem (DB-25)
DB-9 Software Handshaking (DB-25, XON/XOFF)
DB-9 Hardware Handshaking (DB-25, Ready/Busy)
DB-9 to Modem (DB-25)
DB-9 Female DB-25 Male
Signal Pin Pin Signal
GND Shell --- Shell GND (cable shield)
TxD 3 ----- 2 TxD
RxD 2 ----- 3 RxD
RTS 7 ----- 4 RTS
CTS 8 ----- 5 CTS
DSR 6 ----- 6 DSR
SG 5 ----- 7 SG
DCD 1 ----- 8 DCD
DTR 4 ----- 20 DTR
RI 9 ----- 22 RI
To connect to a modem, use a standard "straight-through" cable.
DB-9 Software Handshaking (DB-25, XON/XOFF)
DB-9 Female DB-25 Male
Signal Pin Pin Signal
GND Shell --- Shell GND (cable shield)
RxD 2 ----- 2 TxD
TxD 3 ----- 3 RxD
SG 5 ----- 7 SG
This simple DB-25 terminal/printer cable is a three-wire null modem
cable. Transmitted Data on one end of the cable is connected to
Received Data at the other end, and vice versa.
The male DB-25 end can be plugged directly into most serial
terminals and printers without any adapters. The female DB-9 end
plugs directly into one of the DB-9 connectors on the USB module.
In most cases, serial terminals and printers need only a three-wire
connection. Digi device driver software supports XON/XOFF (software)
handshaking, so the only signal lines necessary are Transmitted
Data (TxD), Received Data (RxD), and Signal Ground (SG).
DB-9 Hardware Handshaking (DB-25, Ready/Busy)
DB-9 Female DB-25 Male
Signal Pin Pin Signal
GND Shell --- Shell GND (cable shield)
RxD 2 ----- 2 TxD
TxD 3 ----- 3 RxD
+-- 4 RTS
|
+-- 5 CTS
SG 5 ----- 7 SG
CTS 8 ----- 20 DTR
This terminal/printer cable is valid with any Digi DB-9 USB serial
port. Most terminals and printers use Data Terminal Ready (DTR) for
Ready/Busy hardware handshaking. The cable shown supports this
method. (Note that pins 4 and 5 of the DB-25 are connected together.)
Some Okidata printers use a control signal on pin 11, called
Supervisory Send Data (SSD) instead of DTR. In this case, simply
connect CTS on the female DB-25 side to pin 11 of the male DB-25,
instead of pin 20.
Other printer manufacturers may use different methods of flow
control. Consult your printer=92s documentation for specific wiring
requirements.
GENERAL CABLE INFORMATION
This section contains the following topics:
Cable Requirements
Grounding Requirements
Environment Requirements
Data Rate Information
Transmission Errors
Cable Requirements
EIA-232 serial interface cables should be shielded, low capacitance
cables, ideally designed specifically for serial data transmission.
EIA-422 interface cables should be shielded twisted-pair cables.
Each signal requires two leads (one twisted pair of wires) to
complete a balanced voltage digital circuit. The shield should be
connected to the Chassis Ground of the devices at both ends of the
interface cable.
Grounding Requirements
EIA-232 interface cables should have the shield grounded at both
ends of the cable. Chassis Ground--available on the shell of Digi=92s
DB-9 connectors--is ideal for this purpose.
EIA-422 interface cables must provide a ground path between the
devices to be connected. This ensures the integrity of data
transfers and control signals. This should be connected to the
Chassis Ground of each device. Digi recommends using the cable
shield for this purpose.
Environment Requirements
While good shielding provides reasonable protection against "noise"
(Electro-Magnetic Interference, or EMI), cables should still be
routed away from noise sources wherever possible. Avoid laying
cables in close proximity to transformers, generators, motors,
fluorescent lights, etc.
Data Rate Information
The maximum date rate which may be used for EIA-232 connections is
primarily determined by the quality and length of the interconnecting
cable. The quality of the cable (for transmission purposes) is
generally determined by the capacitance per foot rating of the cable.
The following table gives the recommended maximum cable length for a
given baud rate. Longer cables may be implemented at the user=92s
discretion.
Baud Rate Max Cable Length
57,600 or less 100 feet
115,200 80 feet
230,400 40 feet
460,800 20 feet
921,600 10 feet
The table assumes the following:
1. The maximum length is the amount of cable which may be connected
to a Digi supplied interconnect device such as a USB module.
2. Maximum length is based on a cable rated at:
12.3 pF/foot, conductor to conductor
22.4 pF/foot conductor to shield
Transmission Errors
If transmission errors occur, attempt the following to determine the
cause of the problem:
1. Reduce the baud rate.
2. Reduce the cable length.
3. Use a cable with a lower capacitance per foot rating.
In situations where low-capacitance cable is unavailable, or very
long cable runs are required, "short-haul" modems, available from
suppliers such as Black Box, can be used to increase the effective
range of the EIA-232 interface. Short-haul modems are similar to
standard modems, except that they are connected directly to each
other via a cable instead of going through a telephone circuit.
Download Driver Pack
After your driver has been downloaded, follow these simple steps to install it.
Expand the archive file (if the download file is in zip or rar format).
If the expanded file has an .exe extension, double click it and follow the installation instructions.
Otherwise, open Device Manager by right-clicking the Start menu and selecting Device Manager.
Find the device and model you want to update in the device list.
Double-click on it to open the Properties dialog box.
From the Properties dialog box, select the Driver tab.
Click the Update Driver button, then follow the instructions.
Very important: You must reboot your system to ensure that any driver updates have taken effect.
For more help, visit our Driver Support section for step-by-step videos on how to install drivers for every file type.