fall back switch

KUUMIC OY

DATA TRANSFER KU13.1

FALL-BACK SWITCHFBS KU13.1

Technical Reference

29.10.1996

KUUMIC OY


CONTENTS

1. INTRODUCTION..............................................................................................................1

2. OPERATION LOGIC .......................................................................................................3

3. OPERATION MODES......................................................................................................4

3.1. Duplicated Lines ....................................................................................................................................................4

3.2. Duplicated Hosts....................................................................................................................................................5

3.3. Hot Standby ...........................................................................................................................................................6

3.4. Duplicated Hosts and Lines ..................................................................................................................................7

3.5. Fully Duplicated ....................................................................................................................................................8

4. HARDWARE DESIGN .....................................................................................................9

5. CONFIGURATION.........................................................................................................10

5.1. Power Supply.......................................................................................................................................................10

5.2. Common Line C...................................................................................................................................................11

5.3. Selectable Line .....................................................................................................................................................12

5.4. Settings .................................................................................................................................................................12

5.5. Indicators .............................................................................................................................................................13

6. APPENDIX.....................................................................................................................14

6.1. Layout ..................................................................................................................................................................14

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1. INTRODUCTION

The KU13.1 FBS (Fall Back Switch) is an Euro1-size unit for connecting RS-232communication links between modems and host computers and providing backup linesfor them. The FBS boards are installed in a 19” subrack: KU20 communication centerwhich can also hold Euro1-size modems KU18 and power supply unit. RS-232 and powersupply cables are connected via KU20 backplanes.

KU20 COMMUNICATION CENTER

POWER SUPPLY

OUTPUT OK

KU23

OM

IN

C

T

RO

TxD

RxD

FALL-BACKSWITCH

KU13.1

STANDBYSELECT

C

HOT

OM

IN

C

T

RO

TxD

RxD

FALL-BACKSWITCH

KU13.1

STANDBYSELECT

C

HOT

OM

IN

C

T

RO

TxD

RxD

FALL-BACKSWITCH

KU13.1

STANDBYSELECT

C

HOT

OM

IN

C

T

RO

TxD

RxD

FALL-BACKSWITCH

KU13.1

STANDBYSELECT

C

HOT

Several parts of the communication system can be duplicated with the KU13.1 FBS

SINGLE HOST - DUPLICATED LINES

MicroSCADA

C A

BFBSRS-232

RS-232

RS-232

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DUPLICATED HOSTS - ONE LINE

MicroSCADA

CA

B FBS RS-232RS-232

MicroSCADA

RS-232

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2. OPERATION LOGIC

Connects line Cto line B.

Connects line Cto line A.

yes

no

noIs there DTR/CD-signal on line A?

Connects line Cto line B.

yesTimeout?

Picture ku13I.drw

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3. OPERATION MODES

3.1. Duplicated Lines

FBS

HOST

M

M

M

M

FBSC

CASE 1 Duplicated lines

FBS activated by carrier detect

STATION

CA

B B

A

MicroSCADA

RS-232

A computer is connected to the connector C. The configuration switches S2-24 are setto DTE. The switch S25 is closed. These settings apply for both FBC’s.

As long as the CD signal is active on side A, the communication path is connected tothat side. When the CD signal is not detected on side A as the timeout delay expires,the communication path is switched to side B. The timeout delay is adjustable by trimmerR7.

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3.2. Duplicated Hosts

FBS

HOST

MODEM

MC

CASE 2 "Warm stand by"Duplicated host

FBS activated by A, DTR

STATIONA

B

HOST

A

B

MicroSCADA

RS-232

MicroSCADA

RS-232

MODEM

M

LINE

A modem is connected to the connector C. The switches S2-24 are set to DCE. Theswitch S25 is closed.

As long as the DTR signal is active on side A, the communication path is connected tothat side. When the DTR signal is not detected on side A as the timeout delay expires,the communication path is switched to side B. The timeout delay is adjustable by trimmerR7.

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3.3. Hot Standby

FBS

HOST

M MC

CASE 3 "Hot stand by"

FBS activated by last rising DTR

STATIONA

B

HOST

A

B

MicroSCADA

RS-232

MicroSCADA

RS-232

MODEM MODEMLINE

A modem is connected to the connector C. The switches S2-24 are set to DCE. Since theHot Standby mode is used, the switch S26 is closed.

The communication path is connected to the side, where the DTR signal is most recentlydetected. The initially active side (A or B) can be selected with switch S1.

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3.4. Duplicated Hosts and Lines

HOST

M

M

M

M

FBS

CASE 4 Duplicated hosts and lines

FBS activated by carrier detect

STATION

C

B

A

A

BHOST

MicroSCADA

RS-232

MicroSCADA

RS-232

MODEM MODEM

MODEMMODEM LINE

LINE

A computer is connected to the connector C. The switches S2-24 are set to DTE. Theswitch S25 is closed.

As long as the CD signal is active on side A, the communication path is connected tothat side. When the CD signal is not detected on side A as the timeout delay expires,the communication path is switched to side B. The timeout delay is adjustable by trimmerR7.

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3.5. Fully Duplicated

FBS

HOST

M

M

M

M

FBS

C

CASE 5 All duplicated

FBS activated by A, DTR and instation end by carrier detect

STATION

C

A

B

B

A

HOST

A

B

FBS

A

B

CMicroSCADA

RS-232

MicroSCADA

RS-232

RS-232

RS-232

MODEM

MODEM MODEM

MODEMLINE

LINE

A modem is connected to the connector C on both FBS’s. The configuration switches areset to DCE and the switch S25 is closed. A station is connected to connector C. Theswitches S2-24 are set to DTE. The switch S25 is closed.

The upper FBS selects the connection line according to the DTR signal on Host A. Whenthere is no signal detected during the timeout delay, the FBS connects the communicationto host B. This FBS connects the communication path according to the modem CD signal.When there is no signal detected on side A during the timeout delay, the FBS connectsthe communication path to side B.

The lower FBS works in the same way as the upper one, except that the first selection isHost B.

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4. HARDWARE DESIGN

The KU13.1 FBS is a solid state switch used to backup and connect communicationlines. The hardware is a single Eurosize card. The card has a built-in switching regulator.It accepts a power supply with a range of 7 - 33 VDC.

The receiver interface transforms the RS-levels to the TTL-levels and transmitter inter-face converts the TTL-signals to the RS-levels. The switching is made by the TTL- levels.

The Hot Standby mode is based on a Schmitt-trigger latch circuit. It can be preset withthe switch located on the front panel.

The timeout period is generated by a one shot timer chip. The timeout delay can beadjusted with a trimmer R7.

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5. CONFIGURATION

There are two D-connectors (D25S) for the selectable lines A and B, and RJ-45connector for the common line C. The common line C can also be connected to an on-board D-connector (D25S).

X4

X11

X2

AX6

21

X3

2X5

1

GND+V

ac

COMMONSELECT

1

B

C

5.1. Power Supply

The power line is connected to the backplane connector X5.The GND level is connected to the pin 2 and positive voltage to the pin 1. Thepower supply input voltage range is 7-33VDC.

2POWER SUPPLY

1

GND+V

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5.2. Common Line C

The common line C is connected to the backplane board as follows:

1 8

RJ45 FRONT VIEW

RJ4512345678

D-25P2282073254

Signal RICDDTRGNDRxDTxDCTSRTS

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The common line can be alternatively connected to the on-board D-connector. In thatcase, C = DTE.

pin 1 = PGpin 2 = TxDpin 3 = RxDpin 4 = RTSpin 5 = CTSpin 6 = DSRpin 7 = GNDpin 8 = CDpin 20 = DTRpin 22 = RI

5.3. Selectable Line

The selectable line is on the backplane board with the connector A or B. Theyare both D25-female connectors.

pin 1 = PGpin 2 = TxDpin 3 = RxDpin 4 = RTSpin 5 = CTSpin 6 = DSRpin 7 = GNDpin 8 = CDpin 20 = DTRpin 22 = RI

5.4. Settings

S1 LEFT on the Hot Standby mode triggers the connectionto line A

RIGHT on the Hot Standby mode triggers the connectionto line B

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S2-24 are always set to the same position depending on the C = DCE or DTE

C = DCE a modem is connected to the connector CC = DTE a computer is connected to the connector C

S25-27case A: S25 is closed, the timeout delay is activecase B: S26 is closed, Hot Standby modecase C: S27 is closed, Common Select mode

The Common Select mode slave boards change theirselections at the same time commanded by the masterboard.The master board S27 and S25 (timeout) or S26 (HotStandby) is selected.There is one master FBS board in thedatacommunication rack and one to four slave boards.The Common Select line is chained to every board.Ifmore than one backplane board is used, the CommonSelect line is chained to the next backplane board(X6).

5.5. Indicators

H1 upper line A TxDH1 lower line B TxD

H2 upper line A RxDH2 lower line B RxD

H3 upper line A DSRH3 lower line B DSR

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6. APPENDIX

6.1. Layout

S5S6

S3S4

C9S8S9

C10C17 S7C15

C8C16

C2C1

C44

S2

C43

C5C12

C46

C11C4

S25

S27

S26

C47C7C14C6

C13

C39

C45 C41

C42

C40

S18S19

S17

C38

C37

S22

S20S21

C31

C30

C23

C24

S12S13

S10S11

S15S16

S14

S23

C32

S24

C35

C36

C33

C34

C27

C19

C20

C25

C18

C26D1

C22

C21

C29

C28

R5

D7D6D5

X2N1

L1

V2C3

R7

R6

R4

+

R3

R2 V4D8

X1

V10

R8

R10

D9

D4

V11

RN1

H2

H1

H3

V7V6

R1 D10

V5R9

V8V9

V3

C = DTEC = DCE

V1

D3D2

R11 R12

S1

COMMON SELECT

CD

COMMON SELECT

HOT STAND BY

DTR

NC

ACTIVATED BY:

DIRECTION:

S26

S2-S24

S27

S25

fall back switch

Documents

hot standby mode

timeout delay expires

common select line

hot standby

power supply

timeout delay

switches s2

cd signal