Patton electronic 285, RS-232, 285S, RS-485 User Manual

USER
MANUAL

MODEL 285
and 285S

RS-232 to RS-485
Interface Converters

SALES OFFICE
[phone]
TECHNICAL SUPPORT
[phone]
http://www.patton.com

Part# 07M285-B
Doc# 047012UB
Revised 9/29/93

Revision C and above

1.0 WARRANTY INFORMATION

Patton Electronics warrants all Model 285 components to be free
from defects, and will—at our option—repair or replace the product
should it fail within one year from the first date of shipment.

This warranty is limited to defects in workmanship or materials,
and does not cover customer damage, abuse, or unauthorized modifi­cation. If this product fails or does not perform as warranted, your sole
recourse shall be repair or replacement as described above. Under no
condition shall Patton Electronics be liable for any damages incurred
by the use of this product. These damages include, but are not limited
to, the following: lost profits, lost savings, and incidental or conse­quential damages arising from the use of or inability to use this prod­uct. Patton Electronics specifically disclaims all other warranties,
expressed or implied, and the installation or use of this product shall
be deemed an acceptance of these terms by the user.

1.1 RADIO AND TV INTERFERENCE

The Model 285 generates and uses radio frequency energy, and if
not installed and used properly—that is, in strict accordance with the
manufacturer's instructions—may cause interference to radio and tele­vision reception. The Model 285 has been tested and found to comply
with the limits for a Class A computing device in accordance with the
specifications in Subpart J of Part 15 of FCC rules, which are designed
to provide reasonable protection from such interference in a commer­cial installation. However, there is no guarantee that interference will
not occur in a particular installation. If the Model 285 does cause inter­ference to radio or television reception, which can be determined by
disconnecting the RS-232 interface, the user is encouraged to try to
correct the interference by one or more of the following measures:
moving the computing equipment away from the receiver, re-orienting
the receiving antenna, and/or plugging the receiving equipment into a
different AC outlet (such that the computing equipment and receiver
are on different branches).

1.2 SERVICE

All warranty and non-warranty repairs must be returned freight
prepaid and insured to Patton Electronics. All returns must have a
Return Materials Authorization number on the outside of the shipping
container. This number may be obtained from Patton Electronics
Technical Service at [phone].

Packages received without an

RMA number will not be accepted.

Patton Electronics' technical staff is also available to answer any
questions that might arise concerning the installation or use of your
Model 285. Technical Service hours: 8AM to 5PM EST, Monday

through Friday.

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2.0 GENERAL INFORMATION

Thank you for your purchase of this Patton Electronics product.
This product has been thoroughly inspected and tested and is warrant­ed for One Year parts and labor. If any questions or problems arise
during installation or use of this product, please do not hesitate to con­tact Patton Electronics Technical Support at [phone].

2.1 FEATURES

• Bi-directionally converts RS-232 signals to balanced RS-485

• Supports up to 50 multipoint device drops in a polling environment

• Supports data rates to 115.2 Kbps on 2 or 4 wires

• Passes transmit & receive data, one control signal each direction

• DTE/DCE switch selectable on RS-232 interface

• Interface powered—no AC power or batteries are required

• Variable high/low impedancesettings

• Carrier can be set as "constantly on" or "controlled by RTS"

2.2 DESCRIPTION

Communicate between RS-485 devices and RS-232C using the
Patton Electronics Model 285 Interface Converter. The Model 285
converts RS-232C signals into balanced RS-485 signals over one or
two twisted pair. Drawing all necessary operating power from the
RS-232 interface, the Model 285 needs no AC power or batteries.

The Model 285 has six convenient configuration switches to adapt
the unit for DCE or DTE, 2 or 4 wire, full or half duplex, and point-to­point or multi-point applications. The Model 285 will support up to 50
polled devices without distance degradation.

The surge protected Model 285S uses high speed avalanche
diodes to clamp voltage surges caused by lightning, motors, switches,
etc. With surge handling capacity of 600W per wire at 1mS, the 285S
has the ability to protect itself and connected equipment from common
damaging surges.

Connector options to the RS-485 are via DB-25 (employing the
RS-530 interface), RJ-11, RJ-45, or terminal blocks with strain relief.

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3.0 CONFIGURATION

The Model 285 is configured using six PC board mounted switch­es. Figure 1 (below) shows the switch locations, along with the loca­tion of the terminal blocks and optional surge protectors:

3.1 SETTING THE DTE/DCE SWITCH

For your convenience, the Model 285 has an externally accessi­ble DTE/DCE switch (see Figure 2, below). If the device connected to
the Model 285 is a modem or multiplexer (or is wired like one), set the
switch to "DTE". This setting causes the Model 285 to behave like
Data Terminal Equipment and transmit data on pin 2.

If the device connected to the Model 285 is a PC, terminal or host
computer (or is wired like one), set the switch to "DCE". This setting
causes the Model 285 to behave like Data Communications Equipment
and transmit data on pin 3.

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3.2 SETTING CONFIGURATION SWITCHES SW1 AND SW2

The five switches shown in Figure 3 (below) configure the Model
285 for RTS/CTS delay, echo, method of carrier control, impedance,
and 2-wire/4-wire operation. These switches are located

internally

on
the Model 285's PC board. To access SW1 and SW2, use a small flat
blade screw driver to pop open the Model 285's case as shown in
Figure 4 (below):

4

DCE/DTE

Switch

2-wire/4-wire

Switch

Surge

Suppressors

(285S only)

Terminal

Block

Control

Switches

"ON"

"OFF"

SW2SW1

Figure 1. Model 285 board, showing switch locations

Figure 2. Close up of external DCE/DTE switch

Figure 3. Close up of switches SW1 and SW2 on the PC board

Figure 4. Opening the Model 285's plastic case with a small screw driver

DCE DTE