Versitron F282x User manual

F282x

FOM II Series

Fiber Optic Modem

Technical Manual

February 1999

Revision C

VERSITRON

83 A be Drive / Suite C

Newark, DE 19702

www.versitron.com

PROPRIETARY ATA

A data in this manua is proprietary and may not be disc osed,

used or dup icated, for procurement or manufacturing purposes,

without prior written permission by

VERSITRON, Inc

WARRANTY

A VERSITRON products are warranted against defects in materia s and workmanship for one year

from date of de ivery. We wi repair or, at our option, rep ace parts which during norma usage

prove to be defective during the warranty period provided that:

1. You ca VERSITRON at (800) 537-2296 and obtain a Return Authorization Number. This number

must be referenced on the box the item is shipped in.

2. Shipping charges are pre-paid.

No other warranty is expressed or imp ied and we are not iab e for consequentia damages. For

repairs outside of the warranty period, the same procedure must be fo owed.

iii

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TABLE OF CONTENTS

PARAGRAPH TITLE PAGE

SECTION 1: ESCRIPTION OF EQUIPMENT

1.1 INTRODUCTION........................................................................................................... 1

1.2 DESCRIPTION OF EQUIPMENT ................................................................................. 1

1.2.1 FUNCTIONAL C ARACTERISTICS .......................................................................... 1

1.2.2 P YSICAL C ARACTERISTICS ................................................................................ 1

1.3 SPECIFICATIONS ......................................................................................................... 4

SECTION 2: INSTALLATION

2.1 GENERAL ...................................................................................................................... 5

2.2 SITE SELECTION.......................................................................................................... 5

2.3 POWER REQUIREMENTS ........................................................................................... 5

2.4 SWITC SETTINGS...................................................................................................... 5

2.5 TIMING MODE.............................................................................................................. 7

2.5.1 SOURCE TIMING.......................................................................................................... 7

2.5.2 TERMINAL TIMING ..................................................................................................... 7

2.5.3 INTERNAL TIMING...................................................................................................... 8

2.6 LOOPBACK ................................................................................................................... 9

2.6.1 FIBER/COPPER LOOPBACK....................................................................................... 9

2.6.2 REMOTE/LOCAL LOOPBACK.................................................................................... 9

2.7 INITIAL C ECKOUT PROCEDURE ........................................................................... 9

SECTION 3: OPERATION

3.1 INTRODUCTION........................................................................................................... 10

3.2 STATUS INDICATORS/AUDIBLE ALARM............................................................... 10

3.3 OPERATING CONTROLS ............................................................................................ 10

SECTION 4: THEORY OF OPERATION

4.1 INTRODUCTION........................................................................................................... 11

SECTION 5: MAINTENANCE AN TROUBLESHOOTING

5.1 INTRODUCTION........................................................................................................... 12

5.2 FAULT ISOLATION...................................................................................................... 12

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LIST OF ILLUSTRATIONS

FIGURE TITLE PAGE

1. OVERALL VIEW, F282X MODEM.................................................................................. 2

2. INTERFACE EXTENDER CONFIGURATION ............................................................... 2

3. MODEM LINK CONFIGURATION.................................................................................. 3

4. SWITC SETTINGS.......................................................................................................... 6

5. INTERNAL TIMING MODES........................................................................................... 8

LIST OF TABLES

TABLE TITLE PAGE

1. ENCLOSURES / C ASSIS................................................................................................ 3

2. SWITC 3 SETTINGS FOR INTERNAL TIMING.......................................................... 6

3. MODEL F282X SWITC SETTINGS............................................................................... 7

4. NON-OPERATIONAL INDICATORS .............................................................................. 12

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SECTION 1

ESCRIPTION OF EQUIPMENT

1.1 INTRO UCTION

This manual provides general and detailed information on the installation and operation of the

Model F282X FOM II Series Fiber-optic Modems. Section 1 contains a general description of the

equipment. Section 2 covers installation instructions. Section 3 contains operating instructions. Section

4 provides the theory of operation. Section 5 contains maintenance and troubleshooting information.

Figure 1 is an overall view of the Model F282X products.

Model Number Part Number Description

F2822 19932-02 RS-530, 0-76.8 Kbps, multimode, 850nm, ST connectors,

2 Km operational distance.

F2824 19932-04 RS-530, 0-76.8 Kbps, multimode, 1300nm, ST connectors,

6 Km operational distance.

F2825 19932-05 RS-530, 0-76.8 Kbps, multimode, 1300nm, ST connectors,

14 Km operational distance.

1.2 ESCRIPTION OF EQUIPMENT

1.2.1 Functional Characteristics

The Model F282X products are fiber-optic links designed for use as an RS-530 interface

extender (See Figure 2) or a modem link (See Figure 3). These units are DTE/DCE switch selectable

and interface with other VERSITRON FOM II series F282X Fiber Optic Modems. Model F2822 uses

multimode fiber-optic cable of up to 2 Km (6,560 ft.), Model F2824 uses multimode fiber optic cable of

up to 6 Km (19,680 ft.) and Model F2825 uses single mode fiber optic cable of up to 14 Km (45,920 ft.).

The link has a maximum data rate of 76.8 Kbps, providing synchronous, asynchronous or isochronous

full-, half-duplex, or simplex data transmission with fully transparent operation. The unit has internal

clock generation for 18 set frequencies. The Model F282X FOM II modems fully support the interface

control signals associated with the EIA RS-530 and MIL-STD-188-114 standards. This is accomplished

by multiplexing the control signals along with clock and data signals and transmitting this serialized

signal to the remote unit. At the remote unit the signal is demultiplexed and applied to the interface.

1.2.2 Physical Characteristics

The Model F282X FOM II products measure 7.0" wide x 0.84" high x 11.6" deep and are

designed to be placed in a variety of VERSITRON enclosures and chassis (see Table 1 for dimensions of

enclosures and chassis). "Desktop" options include both single- and dual-card enclosures. Rack-mount

options include a 2-card and 20-card chassis. The Unit requires a wall transformer for desktop or 2-card

rack mount operation, with a one-pin connector for electrical input on the back of the card. There is a

female DB25 connector for the RS-530 interface and two ST connectors for the fiber-optic interface,

also on the back of the card. The unit requires a VERSITRON Model AC150W rack-mount power

supply for 20-card operation. Two power supplies are required for redundancy. The unit has seven

indicators: power (PWR), alarm (ALM), transmit data (TXD), receive data (RXD), transmit clock

(TXC), receive clock (RXC), and loopback (LB).

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1 2

SW6

1 2

R25

1 2

R19DS7

C27

C26

R30

C11

DCE

DTE

SW5 THRU SW11

TYPICAL SETTINGS

OFF

C25 U19

C24 U20 SW11

U12

U14

DCE SW10

DTE

U17 C20

SW5

1 2

SW7

R26

R27

DTE

DCE

13 25

SW9

SW1

DS6

DS5

R18

R17

DS4

DS3

R16

R15

DS2

R14

DS1 R13

R21

C19

1 2 3

RN2 1

R12

TP1

C22

R11

C13

C15

C18

C12

U15

C23

R10 R8

SW4

4 5 6 7 8

JP1

C10

C28

GND

U18

U13

R22 C21

R28

R20 R1

R24

C6 R23

R29

Q2 R5

C14

RN1

SW3

SW8

CR3 J4

114

FGND

CR1F1 P1

U16

ERSITRON

MADE IN USA

FIGURE 1. OVERALL VIEW, F282X MO EMS

Transmit Data + <

Transmit Data +

Transmit Data − <

Transmit Data −

Request to Send + <

Request to Send +

Request to Send − <

Request to Send −

Data Terminal Ready + <

Data Terminal Ready +

Data Terminal Ready − <

Data Terminal Ready −

Transmit Clock (TT) + <

Transmit Clock (TT) +

Transmit Clock (TT) − <

Transmit Clock (TT) −

Receive Data + >

> Receive Data +

Receive Data − >

> Receive Data −

Clear to Send + >

> Clear to Send +

Clear to Send − >

> Clear to Send −

Data Set Ready + >

> Data Set Ready +

Data Set Ready − >

fiber cable 22

> Data Set Ready −

Signal Ground 7

Signal Ground

Carrier Detect + >

> Carrier Detect +

Carrier Detect − >

> Carrier Detect −

Transmit Clock + >

> Transmit Clock +

Transmit Clock − >

> Transmit Clock −

Receive Clock + >

> Receive Clock +

Receive Clock − >

> Receive Clock −

Local Loopback >

Local Loopback

Remote Loopback >

Remote Loopback

Test Mode >

> Test Mode

Frame Ground 1

Frame Ground

LOCAL MODEM

DTE

DCE

REMOTE MODEM

FIGURE 2. INTERFACE EXTEN ER CONFIGURATION

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Receive Data + <

< Transmit Data +

Receive Data − <

< Transmit Data −

Clear to Send + <

< Request to Send +

Clear to Send − <

< Request to Send −

Data Set Ready + <

< Data Terminal Ready +

Data Set Ready − <

< Data Terminal Ready −

Receive Clock + <

< Transmit Clock (TT) +

Receive Clock − <

< Transmit Clock (TT) −

Signal Ground 7

> 7

Signal Ground

Transmit Data + >

fiber cable 3

Receive Data +

Transmit Data − >

Receive Data −

Request to Send + >

Clear to Send +

Request to Send − >

Clear to Send −

Data Terminal Ready + >

Data Set Ready +

Data Terminal Ready − >

Data Set Ready −

Transmit Clock (TT) + >

Receive Clock +

Transmit Clock (TT) − >

Receive Clock −

Frame Ground 1

Frame Ground

LOCAL MODEM

DCE

REMOTE MODEM

FIGURE 3. MO EM LINK CONFIGURATION

Model Number Dimensions Description Power Supply Required

HF 1 1.31" x 7.12" W x 11.6" D Single Card Standalone Enclosure PSAC08 (US) or PSAC09 (Eur)

HF 2 2.31" x 7.12" W x 11.6" D Dual Card Standalone Enclosure PSAC08 (US) or PSAC09 (Eur)

HF 2SS 1.72" x 19" W x 13.75" D 2-Slot Rack Mount Chassis PSAC08 (US) or PSAC09 (Eur)

HF 20 7" x 19" W x 11.6" D 20-Slot Rack Mount Chassis AC150W (US & Eur)

TABLE 1. ENCLOSURES / CHASSIS

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1.3 SPECIFICATIONS

Data Rate: Any data rate from 50 Bps to 76.8 Kbps; synchronous/asynchronous/isochronous. DTE

source timing applications above 56 Kbps may be dependent upon cable length. Consult factory to

discuss your specific application and configuration requirements.

Operating Mode/Range: Simplex, alf- or Full-duplex operation over fiber-optic cable pair.

Maximum operating range is 2 Km (6,560 ft.) with 850nm optics or 6 Km (19,680 ft.) with 1300nm

optics.

Optical Interface: ST connectors compatible with 50/125 µM, 62.5/125 µM or 100/140 µM fiber-optic

cable for 850nm multimode operation, 62.5/125 µM fiber-optic cable for 1300nm multimode operation

and 8/125 µM, 9/125 µM or 10/125 µM fiber optic cable for 1300nm single mode operation.

Digital Interface: Signal levels and format conform to EIA RS-530 / MIL-STD-188-114. The F282X

has a female DB25 connector for connecting to a terminal, with a gender changer available for

connecting to a modem. The unit is switch-selectable between DCE and DTE operation.

Sample Rate: Control signals are sampled at an 18.75 k z rate. If an asynchronous data signal is used

instead of a control signal the sample rate will result in 5% distortion at 1 Kbps. Data and clock signals

are sampled at 300 k z.

Dimensions: 7.0" W x 0.84" x 11.6" D.

Power Requirements: 120 VAC with available DC wall transformer (VERSITRON Model: PSAC08

US, PSAC09 EUR) providing 12 VDC, 1 A.

Environment: 0° to +50°C (32° to +122°F) operating temperature; up to 95% relative humidity (non-

condensing); up to 10,000 feet altitude; storage temperature -40° to +70° C.

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SECTION 2

INSTALLATION

2.1 GENERAL

This section contains detailed infordmation on the installation and initial checkout of the Model

F282X FOM II Series Modems. Paragraph 2.2 contains general information on site selection and rack

mounting. Paragraphs 2.3 and 2.4 provide instructions for connecting Model F282X products to your

system and selecting the different options. Paragraph 2.5 has the initial checkout procedures.

2.2 SITE SELECTION

The Model F282X FOM II products are designed to connect to the serial port (DB25 Connector)

of the terminal equipment with a cable (customer supplied). The Modem is designed to be placed in a

VERSITRON Model F-1 or F-2 desktop enclosure, or rack mounted in a VERSITRON Model F-

2SS or Model F-20 19-inch standard chassis. The enclosure and chassis dimensions are provided in

Table 1 in the previous section. When placed in a desktop enclosure, space for the transformer must also

be provided.

2.3 POWER REQUIREMENTS

The Model F282X FOM II products are designed to operate from an AC power transformer or a

DC power source with a DC voltage of +12 VDC. Before inserting the power transformer

(VERSITRON Model PSAC08 US, PSAC09 EUR) into an AC power source, the plug should be

connected to the Modem. There are no special tools required. DC power may be used instead of the

power transformer if available. This requires a 2.5 mm socket with the positive voltage on the center

and the common on the concentric using +12 VDC at 1 A.

2.4 SWITCH SETTINGS

There are a number of switches on the circuit card of the Model F282X modem, used to select

between DTE/DCE operation, internal/external clock selection, the internal clock data rate, and several

loopback functions. Figure 4 shows the physical location of all of the switches, labeled SW1 through

SW11. With the exception of the loopback switch (SW1), which is on the front panel of the modem

card, all of the switches should be set to the desired position prior to applying power to the modem,

and then left in those positions unless the overall link characteristics change.

Switch 3 (SW3), located between the optical modules and the XILINX field programmable gate

array (FPGA) chip, contains 8 ON-OFF switch positions. The first three positions determine the

interface standard that is expected as an input. Since the complete family of F2800 Series Low-Speed

Modems includes products that operate per the RS-232 standard, there are switch positions for settings

that are irrelevant to the Model F282X products, as they operate only with RS-530 standard inputs. For

the same reason, there is no Switch 2 (SW2) on a Model F282X product. For SW3, Position 2 is set to

ON for DCE operation, and OFF for DTE operation. Positions 1 and 3 must remain OFF.

Positions 4 through 8 of SW3 are used to set the clock rate for internal-timing operation. As listed

in Table 2, there are 18 different clock rates that may be chosen by the settings of SW3, Positions 4

through 8.

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DS1

DS6

DS3

DS4

DS5

U16

DS7

SW1

SW11

87654321

SW4

SW9

SW10

SW8

SW7

SW6

SW5

SW3

DS2

MADE IN USA

ERSITRON

DCE

DTE

DCE

DTE

TYPICAL SETTINGS

SW5 THRU SW11

DTE

DCEOFF

JP1

FIGURE 4. SWITCH SETTINGS

SWITCH 3 POSITION SETTINGS:

DATA RATE (Hz): 8 7 6 5 4

75 OFF OFF OFF OFF OFF

150 OFF OFF OFF OFF ON

300 OFF OFF OFF ON OFF

600 OFF OFF OFF ON ON

1200 OFF OFF ON OFF OFF

2400 OFF OFF ON OFF ON

3600 OFF OFF ON ON OFF

4800 OFF OFF ON ON ON

7200 OFF ON OFF OFF OFF

9600 OFF ON OFF OFF ON

14.4K OFF ON OFF ON OFF

19.2K OFF ON OFF ON ON

28.8K OFF ON ON OFF OFF

38.4K OFF ON ON OFF ON

56K ON OFF OFF OFF OFF

57.6K OFF ON ON ON OFF

64K ON OFF OFF OFF ON

76.8K OFF ON ON ON ON

TABLE 2. SWITCH 3 SETTINGS FOR INTERNAL TIMING

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SWITCH POSITION ON OFF Description

1 Front Panel X Loopback enabled

1 Front Panel X Loopback function disabled

2 --- --- --- Does not exist on this modem

3 1 X Circuits set for RS-232 signals (Do not change)

3 1 X Circuits set for RS-530 signals (Do not change)

3 2 X Interface set for DCE

3 2 X Interface set for DTE

3 3 X NOT used for RS-530, set to OFF (Do not change)

3 4 - 8 --- --- Internal Clock rate settings, see Table 2

4 1 X Internal Timing (Clock Generated Internal to Modem)

4 1 X External Timing (Clock Received Externally)

4 2 X Terminal Timing (External clock on pins 24 & 11)

4 2 X Source Timing (External clock on pins 15 & 12)

4 3 X Remote/Local Loopback Circuit ON (Set to REMOTE:

CTSin = RTSout, RTSin = CTSout)

4 3 X Remote/Local Loopback Circuit OFF (Set to LOCAL:

CTSin = CTSout, RTSin = RTSout)

4 4 - 8 X NOT used, set to OFF (Do not change)

5,6,7,8,9,10,11 1 - 2 X Interface set for DTE

5,6,7,8,9,10,11 1 - 2 X Interface set for DCE

TABLE 3. MO EL F282X SWITCH SETTINGS

2.5 TIMING MO E

Model F282x Modems can operate in three different timing modes: Source Timing, Terminal

Timing, and Internal Timing. All timing modes are application specific and can be configured using

Switch 4, Position 1 as listed in Table 3. As shown in Figure 4, Switch 4 (SW4), located to the left of

the FPGA, also contains 8 ON-OFF switch positions. Positions 4 through 8 are not used for the Model

F282x products and should be left in the OFF position.

2.5.1 Source Timing

A realignment circuit is needed in the Source (external) Timing configuration to account for the

inherent delays and jitter introduced by noise and asynchronous sampling at all frequencies. The

realignment circuit is only used on the DTE units. A clock detection circuit checks for a clock signal on

input pins 12 and 15 of the DB25 interface. Without clock signals on pins 12 and 15, no realignment

takes place and data is output from the unit as it was received from the fiber-optic input. With clock

signals present, the realignment circuit processes the data signal recovered from the fiber-optic receiver

before it is output onto pins 2 and 14. In Source Timing mode, the F282X modem supports transmitted

and received data, transmitted and received clocks, and eight control signals. The unit shall transmit and

receive balanced signals at a data rate between 50 Bps and 76.8 Kbps with a bit error rate of 1x10-9.

Switch 4, Position 2 should be OFF for source timing.

2.5.2 Terminal Timing

The Terminal (external) Timing mode is the basic mode of operation for the Model F282X FOM II

Series Modems. There is no circuit needed for data realignment. In Terminal Timing mode, the Model

F282X supports transmitted and received data, transmitted and received clocks, and eight control

signals. Balanced signals, at a data rate from 50 Bps to 76.8 Kbps, are processed transparently by the

modem, with a bit error rate of 1x10-9. Switch 4, Position 2 should be ON for terminal timing.

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2.5.3 Internal Timing

Model F282X modems can supply clock frequencies internally while configured as an RS-530

DCE. SW3, Positions 4 through 8 allow the user to select 18 different clock frequencies, as listed in

Table 2. The internal timing mode is set by turning on SW4, Position 1. When SW4, Position 1 is in the

ON position, the board is configured as a null modem. In this configuration, the terminal timing (TT)

clock signals on input pins 11 and 24 of the DB25 interface and the transmit clock signals (TXC), input

on pins 12 and 15 of a DTE unit, are disconnected and replaced with the internally generated clock. In a

null modem configuration, the internal clock is used throughout the circuit. In the interface extender

configuration, the internal clock generated by the DCE modem is output on pins 11 and 24 of the DTE

modem (See Figure 5). When SW4, Position 1 is in the OFF position the internal clock is off.

INTERFACE EXTENDER

INTERNAL TIMING -

F / O

DTE

RXC (A)

RXD (A)

RXD (B)

RXC (B)

TXD (A)

TXD (B)

TT (A)

TT (B)

F / O

INTERNAL TIMING -

DCE

OSC

TT (A)

TXD (A)

TXD (B)

TT (B)

TXC (A)

TXC (B)

RXD (A)

RXD (B)

RXC (A)

RXC (B)

NULL MODEM / MODEM LIN

DCE

OSC

RXC (A)

RXD (A)

RXD (B)

RXC (B)

TXD (A)

TXD (B)

TT (A)

TT (B)

TXC (A)

TXC (B)

OSC

DCE

OSC

RXC (A)

RXD (A)

RXD (B)

RXC (B)

TXD (A)

TXD (B)

TT (A)

TT (B)

TXC (A)

TXC (B)

OSC

TXC (A)

TXC (B)

FIGURE 5. INTERNAL TIMING MO ES

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2.6 LOOPBACK

The Model F282X has two loopback features. The first loopback feature allows the user to test the

fiber-optic circuitry of the unit, the fiber-optic circuitry of the unit at the receiving end, the copper

circuitry of the unit, and the copper circuitry of the unit at the receiving end. The second loopback

feature loops the control signals RTS and CTS.

2.6.1 Fiber / Copper Loopback

This loopback feature of the Model F282X allows the user to test the fiber-optic circuitry of the

unit and the fiber-optic circuitry of the unit at the receiving end. The fiber-optic input and outputs are

connected to a multiplexer. The multiplexer is controlled by the front-panel switch (SW1). When SW1

is ON, the multiplexer control bit goes high, the fiber-optic input data is looped to the fiber-optic output

and sent back to the source. The copper signal enters the board through the interface circuitry to the

multiplexer circuit. The signals get multiplexed, demultiplexed and transmitted back to their source.

This is true for all data, clock, and control signals. If the fiber-optic output and input signals match, and

the copper signals match, the optical and interface circuits of both units are working properly. When

SW1 is OFF, the multiplexer control bit goes low, and the unit functions normally.

2.6.2 Remote / Local Loopback

The Remote / Local Switch, SW4, Position 3, is used to loop control signals RTS and CTS. This

is to accommodate equipment that lacks the ability to respond to an RTS signal. When SW4, Position 3

is ON, a CTS input signal is connected to RTS output and an RTS input is connected to CTS output.

When SW4, Position 3 is OFF, CTS-IN is connected to CTS-OUT and RTS-OUT is connected to RTS-

IN. See Table 3.

2.7 INITIAL CHECKOUT PROCE URE

The Model F282X FOM II Series products contain no power on/off switch. Once the unit is

properly installed and power is applied it may be considered fully operational. The power indicator

should remain on as long as power is supplied to the unit

Before beginning system operation the following items should be checked to verify proper

installation:

1. Verify that the power plug is seated fully into the modem or the modem is seated firmly in the rack-

mount enclosure.

2. Verify that the fiber-optic cable is crossed transmit to receive from unit one to unit two.

3. Verify that the alarm LED goes out when the signal is applied to the optical receiver of the F282X.

4. Verify the switch settings for the circuit configuration (i.e. internal/external timing).

If a malfunction is detected during the initial checkout procedure, refer to Chapter 5 for

information on isolating the malfunction in the unit.

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SECTION 3

OPERATION

3.1 INTRO UCTION

This chapter contains a description of the operating controls and indicators associated with the

Model F282X FOM II Series modems. Since the Model F282X is designed for continuous and

uninterrupted operation, there are no operating requirements. Once the Model F282X is powered up it

should remain in service as long as required.

3.2 STATUS IN ICATORS/AU IBLE ALARM

There are 7 indicators on the Model F282X: power (PWR), alarm (ALM), transmit data (TXD),

receive data (RXD), transmit clock (TXC), receive clock (RXC), and Loopback (LOOP). No audible

alarm is available.

3.3 OPERATING CONTROLS

The only operating controls associated with the Model F282X modems are those used to select

between DTE/DCE, internal/external clock selection, internal clock data rate, and the two loopback

functions. These selections are normally made only at the time of installation. Further changes are not

required unless the system requirements change.

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SECTION 4

THEORY OF OPERATION

4.1 INTRO UCTION

Basic operation of the Model F282X is similar to a four-channel, full duplex multiplexer. The first

channel is used for data. The next two channels are used for transmit and receive clock, while the fourth

multiplexer channel is used for aggregated control signals. This technique provides full transparency for

the link, even when both clocks originate at the modem. The modem supplies both transmit and receive

clocks to the Model F282X, which are transmitted through the link and applied directly to the terminal.

The interface control signals are processed in a similar manner. The Request to Send signal from

the terminal is transmitted through the link and applied to the modem. When the modem responds with

Clear to Send, it will be transmitted through the link and applied to the terminal. With this technique,

the terminal will see the RTS/CTS delay established by the modem. The unit is also capable of looping

RTS/CTS for interface equipment that does not support control signals.

If a fully transparent synchronous link is not required, the clock and control paths may be used as

additional asynchronous data paths. The transmit and receive clock inputs will handle data rates from 0

to 76.8 Kbps asynchronously; the control paths will handle data rates up to 1 Kbps with 5% distortion.

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SECTION 5

MAINTENANCE AN TROUBLESHOOTING

5.1 INTRO UCTION

This chapter contains general information designed to isolate a malfunction in the Model F282X to

a replaceable unit. These units are not equipped with redundancy. Therefore, a failure in one of these

units would interrupt service.

5.2 FAULT ISOLATION

The steps in Table 4 should be taken to check a non-operating modem.

STATUS INDICATOR PROBABLE CAUSE CORRECTIVE ACTION

POWER (PWR) LED is off. No AC power. Check that both ends of the Transformer

are connected.

Blown Fuse. Replace with 250V 1A slo-blo fuse.

Other power supply circuit

problem.

Contact VERSITRON Customer Service

for assistance.

LOSS of OPTICAL POWER (LOP)

LED is on.

Incorrect optical signal level

received at receiver input.

1. Check that fiber-optic cable is properly

connected to RX connector.

2. Check that the remote unit power is on

and the TX fiber-optic connector is

connected properly.

3. Measure the optical levels on both ends

(if possible) in order to check the optical

link.

4. Contact VERSITRON Customer

Service for assistance.

DATA and CLOCK (TXD, RXD, TXC,

RXC) LEDs are off or not responding as

expected.

Switches/Jumpers in wrong

position.

Check that the switch/jumper is set for the

correct electrical interface.

No input on the electrical

interface connector.

Check that the interface connector is

connected securely.

DATA AND CLOCK signal inverted. Switches/Jumpers in wrong

position.

Check that the switch/jumper is set for the

correct electrical interface.

DATA signal inverted. Inverted input on the electrical

interface connector.

Check that the interface connector is

wired per interface standard RS-530.

TABLE 4. NON-OPERATIONAL IN ICATORS

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