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RS-232/422 Pinout InformationPinout Information
Aviom® Pro64® products can use Virtual Data Cables™ to
transmit and receive user control data over RS-232 and/or RS-
422. (RS-422 is not supported on every Pro64 product.)
The following table shows the pinout of the RS-232/422 jack.
Note that in the pinout table, some transmit/receive functions
(abbreviated as Tx/Rx) are different for RS-232 versus RS-422.
Pin Function
1 No Connect
2 –Rx (RS-232), –Tx (RS-422)
3 –Tx (RS-232), –Rx (RS-422)
4 +Rx (RS-422)
5 Ground
6 +Tx (RS-422)
7 No Connect
8 No Connect
9 Ground
DB9 cables are available with male-to-male, female-to-female,
and male-to-female connectors. Aviom’s RS-232/422 port uses
a male DB9 connector and therefore requires a cable with a
female connector. The format of the connector at the other end
of the cable (male/female) is dependent upon the equipment
being connected to. However, connection to other equipment
will usually require a female-to-female cable.
There are many different types of DB9 cables available, but
Aviom selected a pinout for our DB9 connector that would
allow both RS-232 and RS-422 connections to be made with
off-the-shelf cables. A “null modem” cable should be used in
RS-232 mode. Unfortunately, there are several different types
of cables referred to as null modem cables. A true null modem
cable crosses pins 2 & 3, 4 & 6, and 7 & 8. Pin 5 will be connected
straight through, but pins 1 and 9 will not (though pin 1 will
be connected to pin 6 at each end). An example of this type of
cable is the L-Com® CSNULL9FF-XA (where X = cable length).
An example of the type of null modem cable that should be
avoided is the L-Com CSNULL9FF-X (where X = cable length).
This is a straight-through cable with the exception of pins 2 and
3, which are crossed.
A true null modem cable is required for the interaction of the
RS-422 termination on pin 4 of the connector with the RS-232
signals. On an RS-232 connector, pins 3, 4, and 7 are outputs;
pins 1, 2, 6, and 8 are inputs. In a standard null modem cable,
pin 4 at one end of the cable will drive pins 1 and 6 at the other
end. With a 100 ohm resistor across pins 3 and 4 on the Aviom
DB9 connector, pin 3 (RS-232 –Tx) will drive pins 1 and 6 at the
other end of the cable through the 100 ohm resistor. This isn’t
a problem for most modern RS-232 implementations as these
signals are ignored and both are inputs.
Although there is no standard DB9 pinout for RS-422, ours
requires a straight-through cable to be used between Aviom
and Yamaha® RS-422 ports for control. An example of this type
of cable is the L-Com CRMN9FF-X (where X = cable length).
If a problem is encountered with RS-232 operation, there are
two things that can be done:
1.
Try another brand of null modem cable.
2.
Cut the wire in the cable going to pin 4. It isn’t
needed for RS-232 operation.
ote: The Aviom RS-232 port does not support the CD, DTR,
P N
DSR, RTS, CTS, or RI signals.
The following table showing the connections for a null modem
DB9 to DB9 crossover cable can be used when making your
own cable.
RS-232 Null Modem Cable Wiring for a DB9 to DB9 Crossover Cable
Pin Signal Direction Pin
1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
Shield Soldered to DB9 Metal on Both Connectors
1157 Phoenixville Pike, Suite 201 • West Chester, PA 19380 USA
Voice: +1 610.738.9005 • Fax: +1 610.738.9950 • www.Aviom.com
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RS-232 requires a null modem cable
wired as a crossover cable. RS-422 uses a
straight-through cable. This table shows
the pinout for RS-232 crossover cable
wiring and can be used when creating a
custom cable. Note that pins 1 and 6 are
tied together on both sides of a crossover
cable.
A-Net and the A-Net icon are registered trademarks of Aviom, Inc.
All other trademarks are the property of their respective owners.
© 2008 Aviom, Inc. All rights reserved.
P/N 9311 1015 0001F rev. 1.1
Information subject to change without notice.
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