Black Box IC485A-R2, IC485AE-R2, IC485C-R2 User Manual

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CUSTOMER

SUPPORT

INFORMATION

SEPTEMBER 1993

IC485A-R2
IC485C-R2

RS-232 ↔ RS-485 Interface Converter

232 485

DSR CTS DATA PWR DSR CTS DATA

RS-232↔ RS-485 INTERFACE CONVERTER

2

FEDERAL COMMUNICATIONS COMMISSION

RADIO FREQUENCY INTERFERENCE STATEMENT

This equipment generates, uses, and can radiate 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 communication. It 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 against such interference when the equipment is operated in a commercial
environment. Operation of this equipment in a residential area is likely to cause interference, in which
case the user at his own expense will be required to take whatever measures may be required to correct
the interference.

Changes or modifications not expressly approved by the party responsible for compliance could void the
user's authority to operate the equipment.

"This digital apparatus does not exceed the Class A limits for Radio noise emission from digital apparatus
set out in the Radio Interference Regulation of the Canadian Department of Communications."

"Le présent appareil numérique n'émet pas de bruits radioélectriques dépassant les limites applicables
aux appareils numériques de la classe A prescrites dans le Règlement sur le brouillage radioélectrique
édicté par le ministère des Communications du Canada."

TRADEMARKS

IBM

®

is a registered trademark of International Business Machines.

RS-232↔ RS-485 INTERFACE CONVERTER

3

Contents

1.0 SPECIFICATIONS.............................................................................................................................4

2.0 INTRODUCTION.............................................................................................................................5

3.0 INSTALLATION................................................................................................................................7

3.1 Jumpers and DIP Switches....................................................................................................7

3.2 Select DTE/DCE Operation ..................................................................................................7

3.3 Physical Installation...............................................................................................................7

3.4 Indicators.............................................................................................................................11

3.5 Interface Pinouts .................................................................................................................14

RS-232

↔

RS-485 INTERFACE CONVERTER

4

Speed —

Approximately 40,000 bps

Indicators —

7 high-efficiency LEDs show the status of RS-232/RS-485 incoming signals and
indicate the power ON/OFF condition.
RS-232 Port: DSR, CTS, DATA
RS-485 Port: DSR, CTS, DATA

Controls —

RS-232 port: DTE/DCE jumper-selectable
RS-485 port: DTE/DCE jumper-selectable

Connectors —

RS-232 port: 25-pin sub-D female
RS-485 port: 37-pin sub-D female

Environmental —

Maximum Storage Temperature: 158°F (70°C)
Maximum Operating Temperature 122°F (50°C)

Power —

115 VAC power supply: ±10%, 100 mA rms
230 VAC power supply: ±10%, 50 mA rms

Size —

IC485A-R2: 2.3"H x 8"W x 11.9"D (5.8 x 20.3 x 30.2 cm)
IC485C-R2: 1.2"H x 7.5"W x 11.4"L (3 x 19 x 28.9 cm)

Weight —

1.8 lb. (0.8 kg)

1.0 Specifications

CHAPTER 2: Introduction

5

The RS-232↔RS-485 Interface Converter
provides bi-directional synchronous or
asynchronous conversion for all commonly used
RS-232 and RS-485 signals. The unit is designed
with one port configured as Data Terminal
Equipment (DTE) and the other as Data
Communications Equipment (DCE). Operation is
not recommended with both ports configured
either DCE or DTE when operating in
synchronous mode.

The unit has two jumper-selectable configurations:
one for connecting RS-485 modem equipment to
RS-232 terminal equipment (DTE to DCE), and
one for connecting RS-232 modem equipment to
RS-485 terminal equipment (DCE to DTE). Both
configurations allow bi-directional data transfer.

A two-wire half-duplex application is shown in
Figure 2-1, followed by a four-wire full-duplex
application diagram in Figure 2-2. An RS-232
cable configuration for an IBM

®

PC is shown in

Figure 2-3.

2.0 Introduction

Figure 2-1. 2-Wire Asynchronous Application

NOTE

The two- and four-wire application
diagrams illustrate only the wiring of
the data leads. All other leads are still
passed through from one port to the
other.

NOTE

Echo is not disabled in 2-wire half-
duplex operation. A carrier signal or
transmitter being enabled on the
RS-485 line will not raise the RTS or CD
signals on the RS-232 port.

NOTE

In a two-wire application, the toggling
of the RTS lead from the RS-232 port
enables and disables the RS-485
transmitter. Because hardware
handshaking (RTS) is required by the
RS-232 standard in order to control the
RS-485 drivers, and RTS is not
supported by most communications
packages despite the fact that it is
software-dependent, you may need a
customized software package in order
to implement any 2-wire application.

RS-232 PORT = DCE
RS-485 PORT = DTE

DB25

IBM PC

OR OTHER

DTE DEVICE

STRAIGHT

CABLE

RS-232/RS-485

INTERFACE

CONVERTER

PINS 22 & 24

ARE JUMPERED

ON THE INTERFACE

CONVERTER

PINS 4 & 6

JUMPERED

ON IC

+B

-A

RS-485

DEVICE

DCE