B&B Electronics 485DSS User Manual

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Distributed Smart Switch

Model 485DSS

Documentation Number 485DSS-0308

This product

Designed and Manufactured

In Ottawa, Illinois

USA

of domestic and imported parts by

B&B Electronics Mfg. Co. Inc.

707 Dayton Road --P.O. Box 1040--Ottawa, IL 61350 PH (815)433-5100--FAX (815)433-5105

Internet: http://www.bb-elec.com orders@bb-elec.com support@bb.elec.com

© 1998 B&B Electronics--January 2008

485DSS-0308Manual

Cover Page

B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100- Fax815-433-5104

B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445

TABLE OF CONTENTS

 

CHAPTER 1: HARDWARE...................................................................

 

1

INTRODUCTION ........................................................................................

 

1

Figure 1. Example of an RS-485/422Multi-NodeNetwork ......................

1

CHECKLIST...............................................................................................

 

1

SPECIFICATIONS .......................................................................................

 

2

Figure 2. Top View of Circuit Board..........................................................

2

PORT CONFIGURATION.............................................................................

 

2

RS-485/422Port..................................................................................

 

2

Table 1. RS-422/485Port ......................................................................

 

3

RS-232Port.........................................................................................

 

3

Table 2. RS-232DTE DB25P Connector Chart ....................................

4

RS-422/485Wiring..............................................................................

 

4

2-WireMode........................................................................................

 

4

Table 3. Component Values For Send Data Timing..............................

5

Figure 3. RS-485Wiring Diagram.............................................................

6

4-WireMode........................................................................................

 

6

Figure 4. RS-422Wiring Diagram.............................................................

7

RS-485AND RS-422TERMINATION.........................................................

7

POWER SUPPLY ........................................................................................

 

7

OPERATION ..............................................................................................

 

8

Figure 5. Simplified Functional Diagram ..................................................

9

COMMUNICATION CONFIGURATION .........................................................

9

DISTRIBUTED SMART SWITCH COMMANDS ..............................................

9

The Command String.........................................................................

 

10

ON Command....................................................................................

 

10

OFF Command..................................................................................

 

11

STATUS REQUEST Command .........................................................

11

SETTING THE 485DSS ADDRESS ............................................................

 

14

Table 4. Address Switch......................................................................

 

14

BINARY FILE TRANSFER.........................................................................

 

15

CHAPTER 2: SOFTWARE ..................................................................

 

16

DESCRIPTION ........................................................................................

 

16

APPENDIX A: ASCII CHARACTER CODES ................................

A-1

APPENDIX B: DECIMAL/HEXADECIMAL CONVERSIONS.....

B-1

Table 5. Hex/Dec Conversions ...............................................................

B-1

APPENDIX C: CABLE CHARTS......................................................

C-1

485DSS-0308Manual

Table of Contents

i

B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100- Fax815-433-5104

B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445

CHART 1. IBM PC DB25 CONNECTOR TO ...........................................

C-1

485DSS RS-232(DTE) PORT............................................................

C-1

CHART3.

RS-232DCE DEVICE W/DB25 CONNECTOR TO ..................

C-1

485DSS RS-232(DTE) PORT............................................................

C-1

CHART2.

IBM PC DB9 CONNECTOR TO .............................................

C-1

485DSS RS-232(DTE) PORT............................................................

C-1

CHART4.

RS-232DCE DEVICE W/DB9 CONNECTOR TO ....................

C-2

485DSS RS-232(DTE) PORT............................................................

C-2

CHART 5.RS-422/4854-WIRE DEVICE TO 485DSSRS-422/485PORTC-2

CHART6.

RS-4852-WIRE DEVICE TO 485DSSRS-485/422PORT. ....

C-2

ii Table of Contents 485DSS-0308Manual

B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100- Fax815-433-5104

B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445

Chapter 1: HARDWARE

Introduction

The RS-485Distributed Smart Switch (485DSS) connects oneRS-232device to anRS-485multi-nodenetwork as shown in Figure 1. To accomplish this, the 485DSS convertsRS-232to an addressableRS-485node. A unique address, from 0 to 255, is user assigned by setting switches on the 485DSS.

Figure 1. Example of an RS-485/422Multi-NodeNetwork

Checklist

The following items should be in the shipping carton:

1.RS-485Distributed Smart Switch

2.Instruction Manual

3.Software

Contact the shippers immediately if any of the items above is missing or has damage.

485DSS-0308Manual

1

B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100- Fax815-433-5104

B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445

Specifications

Model:

485DSS

Size:

4.8"L x 2.15"W x 0.9"H

Power:

+11 to 16 Vdc 75mA

RS-232Connection:

DB-25male (DTE configured)

RS-485Connection:

Terminal Blocks

Communications:

9600 baud, no parity, 8 data bits, 1 stop bit

Figure 2. Top View of Circuit Board

Port Configuration

The 485DSS has a RS-485/422port and aRS-232port. TheRS-485/422signals are on terminal blocks. Table 1 shows you the pinouts and Figure 2 shows you the location of the terminal blocks. TheRS-232signal, in the DTE configuration, connects to a DB25 male connector. Table 2 shows you theRS-232pinouts.

RS-485/422Port

The RS-485port on the 485DSS receives and transmits data to and from theRS-485network. TheRS-485port has a balanced differential line driver and receiver.RS-485allows up to 32 driver and receiver pairs to share atwo-wireparty line network. This port will operate on a4-wirenetwork and is compatible withRS-422devices. Refer to B&B Electronics’ freeRS-422/485Application Note for more information. Refer to Appendix C for cable charts.

2 485DSS-0308Manual

B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100- Fax815-433-5104

B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445

Table 1. RS-422/485Port

 

Terminal

 

RS-422/485

 

Block

 

Signal

 

Signal

Description

Direction of

 

 

 

Port

 

FR GND

Frame Ground

<------>

 

TD(A)(-)

Transmit Data (A)(-)

Output

 

TD(B)(+)

Transmit Data (B)(+)

Output

 

RD(A)(-)

Receive Data (A)(-)

Input

 

RD(B)(+)

Receive Data (B)(+)

Input

 

GND

Signal Ground

<------>

 

+12VDC

Power Supply

Input

RS-232Port

 

 

The RS-232DTE port is an asynchronous port that supports TD and RD signals. In order to make the proper connections to the RS232 port. It is necessary to have a basic understanding of the terms DCE and DTE. The original design for connectingRS-232devices together uses DB25 connectors, and connects a DTE (DataTerminalEquipment) device to a DCE (DataCommunicationEquipment) device. Each device will have inputs on pins that correspond to outputs on the same pins of the other device. For example, a DTE device transmits data out on pin 2 and a DCE device receives data in on pin 2. IBM PC's are DTE devices and modems are DCE devices. Only TD and RD of theRS-232port pass through to theRS-485port when the 485DSS is ON. The 485DSS raises and lowers the RTS output signal on theRS-232port to reflect the connect state of the port. This signal can notify theRS-232device to start communicating to the Host or it can be an alarm output. The Host can monitor the CTS input line to determine if theRS-232device is requesting access to the network. This input line could also be an alarm input.NOTE: If using RTS or CTS lines as alarms the user may have to design additional circuitry to properly interface to the alarm circuits. Refer to cable charts in Appendix C for making your own cables.

485DSS-0308Manual

3

B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100- Fax815-433-5104

B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445

Table 2. RS-232DTE DB25P Connector Chart

 

 

 

Signal

 

 

 

Direction of

Pin #

Signal

Description

RS-232DTE

Port

1

FR GND

Frame Ground

<------>

2

TD

Transmit Data

Output

3

RD

Receive Data

Input

4

RTS

Request to Send

Output

5

CTS

Clear to Send

Input

7

SG

Signal Ground

<------>

RS-422/485Wiring

RS-485receivers also have an enable/disable control line. The 2W/4W jumper selects when to enable and disableRS-485receiver. Setting the jumper to the 4W position constantly enables the receiver which is the same as operating in anRS-422/4854-wiremode. In this position and connected to a2-wirenetwork, all data being transmitted by theRS-485driver echos back through the RS485 receiver. Setting the jumper to 2W(RS-485,2-wiremode) automatically enables the receiver when theRS-485driver disables and visa versa.

To configure the 485DSS for a typical 2-wireparty line network, set the jumper in the 2W position. Refer to Figure 2 for the jumper location.

The EIA RS-485Specification labels data lines with an "A" and "B" designator. SomeRS-485equipment uses a "+" and"-"designator. In almost all cases, the "A" line is the equivalent of the "- " line and the "B" line is the equivalent of the "+" line. See Figure 3 for a wiring example.

2-WireMode

RS-485allowshalf-duplexcommunications of multiple drivers having a control line for enabling and disabling(tri-stating)their outputs. When the 485DSS transmits a status reply message to the Host, the microcontroller will automatically enable the driver before transmitting the first character of the reply and disable the driver after the last character of the reply. When the 485DSS is ON (selected) and theRS-232device is transmitting data to the Host theSendData (SD) control circuit enables and disables the driver. The 485DSS disables the driver when it is not transmitting data to the Host and listens to (receives) all communications on the network.

4 485DSS-0308Manual

B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100- Fax815-433-5104

B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445

SD control automatically enables the RS-485driver by sensing the leading edge of the first character transmitted to theRS-232port. After transmitting the last character, the send data timer circuit waits one character time (1 millisecond at 9600 baud) before disabling theRS-485driver.

There are two components in the timer circuit, a resistor (R15) and a capacitor (C10), that make up the send data control circuit. These components are factory selected for 9600 baud, allowing the send data control to operate at 9600 baud or higher. These two components disable the RS-485driver approximately 1 millisecond after transmitting the last character. To change to a baud rate lower than 9600 baud, or to configure the send data control to match a specific baud rate of theRS-232device, remove R15 and insert the value specified in Table 3 into the R21 position. Use Figure 2 to locate R15 and C10.NOTE: The SD timing circuit does not control theRS-485driver when the 485DSS sends reply messages to the host.

Table 3. Component Values For Send Data Timing

 

 

 

Resistor Value

 

 

Capacitor Value

Baud Rate

Time (ms)

 

R15 (ohms)

 

C10(microfarads)

1200

8.33

 

820K

 

 

.01

2400

4.16

 

430K

 

 

.01

4800

2.08

 

200K

 

 

.01

9600*

1.04*

 

100K*

 

 

.01*

19200

0.520

 

56K

 

 

.01

38400

0.260

 

27K

 

 

.01

56700

0.176

 

16K

 

 

.01

115200

0.0868

 

8.2K

 

 

.01

 

*

Factory Default

 

485DSS-0308Manual

5

B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100- Fax815-433-5104

B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445

Figure 3. RS-485Wiring Diagram

4-WireMode

To configure the 485DSS for RS-485or 422four-wiremode, place the jumper in the 4W position. Refer to Figure 4 for connecting information and Figure 2 for the jumper location. In this position on a4-wirenetwork the Host and theRS-232device can communicate in full duplex.CAUTION: Data loss may occur if the Host sends 485DSS commands while the host is receiving data from the network!

6 485DSS-0308Manual

B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100- Fax815-433-5104

B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445