USER
MANUAL
MODEL 222N
and 222NS
Miniature RS-232 to
RS-422 Converters
CERTIFIED
An ISO-9001
Certified Company
3.0 CONFIGURATION
The Model 222N is designed to be easy to use. There are no
internal jumpers or DIP switches to set, so there is no need to open the
case to configure the unit (you may need to open the case for wire
connection—refer to section 4.0). The only configuration necessary for
operation is proper setting of the external DTE/DCE switch.
The figure below shows the location of the DTE/DCE switch on the
PC board, as well as the location of the terminal block and surge
suppressors ("S" model only).
3.1 SETTING THE DTE/DCE SWITCH
For your convenience, the Model 222N has an externally
accessible DTE/DCE switch (see diagram below). If the device
connected to the Model 222N is a modem or multiplexer (or is wired like
one), set the switch to "DTE". This setting causes the Model 222N to
behave like Data Terminal Equipment and transmit data on pin 2.
If the device connected to the Model 222N is a PC, terminal or host
computer (or is wired like one), set the switch to "DCE". This setting
causes the Model 222N to behave like Data Communications
Equipment and transmit data on pin 3.
4
DCE DTE
DCE/DTE
Switch
Surge
Suppressors
(222NS only)
Terminal
Block
DCE DTE
4.1.2 RS-422 CONNECTION USING RJ-11 OR RJ-45
The RJ-11 and RJ-45 connectors on the Model 222N's RS-422 side
are pre-wired for a standard TELCO wiring environment. The signal/pin
relationships are shown below:
RJ-1
1 SIGNAL RJ-45 SIGNAL
1...................GND* 1 .................N/C
2...................RCV- 2 .................GND*
3...................XMT+ 3 .................RCV-
4...................XMT- 4 .................XMT+
5...................RCV+ 5 .................XMT-
6...................GND 6 .................RCV+
7 .................GND
8 .................N/C
In most modular RS-422 applications, it is necessary to use a
"cross over" cable. The diagram below shows how a cross over cable
should be constructed for an environment where both the Model 222N
and the RS-422 device use a 6-wire RJ-11 connector. Similar logic
should be followed when using RJ-45 connectors or a combination of
the two.
MODEL 222N RS-422 DEVICE
SIGNAL
PIN# COLOR COLOR PIN# 422 SIGNAL
GND
†
1 Blue‡................N/C
RCV- 2 Yellow ..............Red 4 XMT-
XMT+ 3 Green...............Black 5 RCV+
XMT- 4 Red ..................Yellow 2 RCV-
RCV+ 5 Black................Green 3 XMT+
GND
†
6 White ...............N/C
†
Connection to ground is optional
‡
Standard AT&T color codes—yours may be different
6
1 - Blue
2 - Yellow
3 - Green
4 - Red
5 - Black
6 - White
1 - Blue
2 - Orange
3 - Black
4 - Red
5 - Green
6 - Yellow
7 - Brown
8 - Slate
3. Strip back the insulation on each of the 2 twisted pair wires
about .25".
4. Connect
one pair
of wires to XMT+ and XMT- (transmit positive
and negative) on the terminal block, making careful note of which color
is positive, and which color is negative.
5. Connect the
other pair
of wires to RCV+ and RCV- (receive
positive and negative) on the terminal block, again making careful note
of which color is positive, and which color is negative.
Ultimately, you will want to construct a two pair cross over cable that
makes a connection with the RS-422 device as shown below:
Model
222N RS-422 Device
XMT+.............................RCV+
XMT-..............................RCV-
RCV+.............................XMT+
RCV-..............................XMT-
6. If there is a shield around the telephone cable, it may be
connected to "G" on the terminal block. To avoid ground loops, we
recommend connecting the shield at one end only. A ground wire is
not
necessary
for proper operation of the Model 222N.
7. When you finish connecting the wires to the terminal block, the
assembly should resemble the diagram below:
+RCV- G -XMT+
8
11. Insert one captive screw through a saddle washer, then insert
the captive screw with the washer on it through the hole in the DB-25
end of the case. Snap that side of the case closed. Repeat the
process for the other side. This completes the cable installation
process.
4.2 CONNECTION TO THE RS-232 INTERFACE
Once you have configured the Model 222N for DTE or DCE and
connected the twisted pair wires correctly, simply plug the 222N directly
into the DB-25 port of the RS-232 device. After doing so, remember to
insert and tighten the two captive connector screws.
NOTE: If you must use a cable to connect the Model 222N to the
RS-232 device, make sure it is a
straight through
cable of the
shortest possible length—we recommend 6 ft or less.
4.3 OPERATING THE MODEL 222N
Once the Model 222N is properly installed, it should operate
transparently—as if it were a standard cable connection. Operating
power is derived from the RS-232 data and control signals; there is no
"ON/OFF" switch. All data signals from the RS-232 and RS-422
interfaces are passed straight through. All control signals from the RS232 interface are looped back.
NOTE: If your system requires
hardware
flow control, you will
need the Patton Model 285 RS-232 to RS-485 converter. Call
Patton Customer Service at 301-975-1007.
10
APPENDIX B
PATTON MODEL 222N CABLE RECOMMENDATIONS
The Patton Model 222N operates at frequencies of 20kHz or less
and has been performance tested by Patton technicians using twistedpair cable with the following characteristics:
W
ire Gauge Capacitance Resistance
19 AWG/.9mm 83nf/mi or 15.72 pf/ft. .0163 Ohms/ft.
22 AWG/.6mm 83nf/mi or 15.72 pf/ft. .0326 Ohms/ft.
24 AWG/.5mm 83nf/mi or 15.72 pf/ft. .05165 Ohms/ft.
To gain optimum performance from the Model 222N, please keep
the following guidelines in mind:
•
Always
use twisted pair wire—this is not an option.
• Use twisted pair wire with a capacitance of 20pf/ft or less.
• Avoid twisted pair wire thinner than 26 AWG (i.e. avoid higher
AWG numbers than 26)
• Use of twisted pair with a resistance greater than the above
specifications may cause a reduction in maximum distance
obtainable. Functionality should not be affected.
• Environmental factors too numerous to mention can affect the
maximum distances obtainable at a particular site. Use “maximum
distance” figures as a general guideline only
.
12
APPENDIX C
PATTON MODEL PIN ASSIGNMENTS
EIA-422 (EIA-530) Interface
(DB-25 Connector)
EIA-422 Interface
(RJ-11 Female Connector)
EIA-422 Interface
(RJ-45 Female Connector)
NOTE: Signals XMT+ and XMT- are the EIA=422 “A” and “B” transmitters, respectively;
Signals RCV+ and RCV- are the EIA-422 “A” and “B” receivers, respectively.
2- (XMT+) Transmit Data +
3- (RCV+) Receive Data +
Transmit Data - (XMT-) - 14
Receive Data - (RCV) - 16
SIGNAL/PIN # SIGNAL/PIN#
RJ-11 (6 Pin) SIGNAL/PIN #
1 - (G) Ground
2 -(RCV-) Receive Data +
3 -(XMT+) Transmit Data 4 -(XMT-) Transmit Data 5 -(RCV+) Receive Data +
6 - (G) Ground
RJ-45 (8 Pin) SIGNAL/PIN #
1 - no connection
2 - (G) Ground
3 - (RCV-) Receive Data 4 - (XMT+) Transmit Data +
5 - (XMT-) Transmit Data 6 - (RCV+) Receive Data +
7 - (G) Ground
8 - no connection
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