TC Communications TC1720 User Manual

TC1720

RS-422/RS-449 Async/Sync

FIBER OPTIC MODEM

(with Optional Dual Optics)

User's Manual

MODEL:

S/N:

DATE:

Although every effort has been made to insure that this manual is current
and accurate as of date of publication, no guarantee is given or implied
that this document is error free or accurate with regard to any specifica­tion. TC Communications, Inc. reserves the right to change or modify
the contents of this manual at any time without prior notification.

TC Communications, Inc. 17881 Cartwright Road, Irvine, CA 92614

Tel: [phone] Fax: [phone] Web Site: www.tccomm.com Email: [e-mail]

Notice!

© COPYRIGHT 1992-2009. ALL RIGHTS RESERVED.

TC1720

(Optional Dual Optics)

Table of Contents

User's Manual

Rev. 1.4

Chapter 1 - Overview ...................................................................................................3

Description.......................................................................................................................................... 3

Electrical Specifications ................................................................................................................... 3

Virtual Pin Assignments and Theory of Operation ....................................................................... 3

LEDs, DIP Switches and Connectors.............................................................................................. 4

DIP Switch Functions ........................................................................................................................ 5

Front Panel Switches ........................................................................................................................ 5

SW1 Internal PCB Dip Switches...................................................................................................... 5

RS-422/449 Termination Resistor ................................................................................................... 6

Optical Specifications ....................................................................................................................... 6

Optical Redundancy (optional) ........................................................................................................ 7

Dry Contact Alarm Relay................................................................................................................... 7

Power Supply and Rear Panel ......................................................................................................... 7

Chapter 2 - Installation ................................................................................................8

Unpacking the Unit ............................................................................................................................ 8

Equipment Location .......................................................................................................................... 8

Installation Procedure Summary ..................................................................................................... 8

Typical Point to Point Application Diagram .................................................................................... 9

Chapter 3 - Troubleshooting ...................................................................................... 10

General ..............................................................................................................................................10

All LEDs are "Off" .............................................................................................................................10

Alarm LED .........................................................................................................................................10

Optic Cable Types............................................................................................................................10

Calculating the Loss on the Fiber .................................................................................................10

RS-422/449 Cable Verification.......................................................................................................10

Important Warranty Note ................................................................................................................10

Optic Cable Verification ..................................................................................................................11

Chapter 4 - Bench Tests ............................................................................................ 12

General ..............................................................................................................................................12

Test Equipment Requirements ......................................................................................................12

Pre-Installation Tests.......................................................................................................................12

Local Electrical Loopback Test ......................................................................................................13

Local Optical Loopback Test ..........................................................................................................14

Remote Optical Loopback Test ......................................................................................................15

Remote Electrical Loopback Test ..................................................................................................16

Bench Test With Built-In Signal Generator..................................................................................17

Chapter 5 - Component Placement ............................................................................ 18

Chapter 6 - Specifications.......................................................................................... 19

Appendix A................................................................................................................ 20

Return Policy ....................................................................................................................................20

Warranty ............................................................................................................................................20

-2-

TC1720

SD,SD

RD,RD

TT,TT

RT,RT

ST,ST

FRAME GND

SIGNAL GND

to DCE

Fiber Cable

Virtual Connection

SD,SD

RD,RD

TT,TT

RT,RT

to DTE

Virtual Connection

(Optional Dual Optics)

Chapter 1 - Overview

User's Manual

Rev. 1.4

Description

The TC1720 RS-422/RS-449 is an economical and dependable fiber optic modem which links data
communication equipment requiring an RS-422A interface. It supports Asynchronous data speeds of up to
10 Mbps & Synchronous data speeds of up to 5 Mbps and is equipped with a male DB37 connector. A four­position DIP switch provides for Remote & Local Loopback functions, Slave Clock operation & Alarm
disabling capability.

It is available in either rack mount or stand alone versions; the rack mount version can be converted to the
stand alone version with the addition of a sheet metal box. The TC1720 can communicate at distances up
to 4 km using Multimode optics and up to 80 km using Single Mode optics. Fiber optic connectors can be
either ST or FC type. TC1720's design utilizes advanced FPGA (Field Programmable Gate Array) technology
to increase reliability and flexibility.

The TC1720 has multiple LED indicators to ease installation and troubleshooting. These LEDs indicate status
for power, operating voltage, alarm, transmit & receive electrical signals, optical signal and more.

Electrical Specifications

Interface: RS-422/RS-449 Async/Sync
Data Rates: Async Up to 10 Mbps

Sync Up to 5 Mbps

Connector: DB37 Male (DCE/DTE switch selectable)

Virtual Pin Assignments & Theory of Operation

(Connect DTE to DCE device)

TC1720

DCE

SD,SD

4,22 4,22

RD,RD

6,24 6,24

from DTE
device

TT,TT
RT,RT

ST,ST

FRAME GND

SIGNAL GND

17,35

8,26 8,26

5,23

1 1

19

Figure 1. Connecting a DTE to DCE Device

TC1720

DTE

17,35

5,23

19

device

SD,SD

RD,RD

from DTE
device

Transmit timing
(DCE sources)

Transmit timing
(DCE sources)

TT,TT

RT,RT

ST
ST

FRAME GND FRAME GND

SIGNAL GND

Figure 2. Connecting a DTE to DTE Device

Logic Diagram

The TC1720 latches onto the RS-422/RS-449 data by the received clock signal (from user's equipment or
the internal clock generator from the TC1720) to produce an encoded optic signal (with an embedded clock).
The composite optic signal is then transmitted by the optic transmitter through the optic cable to a remote
TC1720's optic receiver. The received optic signal is processed and decoded to separate data and clock from
the composite optic signal and then transmitted out to a remote device.

with Slave Clock

TC1720

DCE

4,22 4,22
6,24 6,24

17,35

8,26 8,26

5 5,23

Internal

generator

23

1

19

Fiber Cable

Clock

TC1720

DCE

17,35

SW3,
Slave clock

Logic Diagram

19

1

ST,ST

SIGNAL GND

device

-3-

LEDs, DIP Switches and Connectors

621

7

RxA

TxA

RxB

TxB

RMTLBDIS ALMLOCLBSLAVE-CLKASYNC/SYNC

FIBER OPTIC MODEM

PWRAALARMVccPWRBRx-AUSE-BDTERx-

B

123

4

123

4

Connector for primary optic link

Connector for optional secondary optic link

solid- major alarm condition (optic input lost)

flash- remote loopback activated by remote unit

3

Switches to initiate (”down” position)

LOCLB- turn on local electrical interface’s loopback

TC1720

(Optional Dual Optics)

User's Manual

Rev. 1.4

RTS

TxClk RxClk

TCCOMM.COM
Made in U.S.A.

5

Status for electrical signal from
local user’s device:
TxD- “transmit data”
RTS- “request to send”
CD- “carrier detect”
TxClk- “transmit clock”

received optic signal status
& DTE indicator
RxA:

- Solidly lit, when optic signal is received “OK” from primary
side (”A” side)

- Flashing, when optic signal lost
RxB:

- Solidly lit, optic received “OK” from secondary side (”B” side)

- Flashing, when optic signal lost or “B” side is not enabled
USE-B:

- Solidly lit, when secondary optic signal is being used due
to primary optic signal lost

- Off, secondary optic receiver is not enabled or primary
optic signal is being used.
DTE:

- Solidly lit, when unit is configured as DTE.

- Off, when unit is configured as DCE.

TxD

RxD
CTS
CD

CD

4

status for received electrical signals
(from remote unit):
RD- “received data” (”TD”)
CTS- “clear to send”(”RTS”
CD- “carrier detect” (”CD”)
RCLK- “received clock” (”TxClk”)

following tests and function:
RMTLB- turn on remote unit’s loopback

SLAVE-CLK - Turns on Slave Clock mode: (RT=ST)
DISALM- disable alarm buzzer and relay

Alarm Indicator, Power Status &
Operating Voltage Status
Alarm (red):
off - normal operation

PWR A: DC power supply from PWR A jack
PWR B: DC power supply from PWR B jack
Vcc: +5 VDC operating voltage power supply

:

NOTE

SLAVE-CLK Switch 3: - DTE it is not used.

- DCE when it is “on” (down position), it turns “on” the Slave-clock mode: (RT=ST).
when it is “off” (up position), it turns “on” the Internal clock mode: (ST=Internal clock) see table 1.

Pins:

Function of SW3

5
23

Sw3

Internal clock

“off” (up position)

Slave clock

“On” (down position)

Figure 3. TC1720's Front Panel

-4-

TC1720

For Oscillator: 8.192Mhz

RMTLBDIS AL

M

LOCLBSLAVE-CL

K

234

3

4

This table shows the

Internal Clock speed

5 - 10M

Internal

8

(Optional Dual Optics)

User's Manual

DIP Switch Functions

Rev. 1.4

For troubleshooting purpose, user can conduct remote loopback and local loopback test. TC1720 also has
a built-in signal generator for user to validate fiber optic link. There are two groups of DIP switches: one
at the front panel, the other one is located at the center of the PC board.

Front Panel Switches

There are four DIP switches located at the front panel. Usually, they are very
useful during installation or troubleshooting. They are described as follows:

1

1 2

DIP #1: Remote loop back. This switch (DIP #1) initiates the Remote loop

back function. The composite optic signal is received from optic "RxA"
and decoded, then looped back to optic "TxA."

DIP #2: Local loop back (for diagnostic use). When DIP #2 is pressed down, an electrical signal loop

is created, the input electrical signal is converted to the TTL level and looped back.

DIP #3: Internal clock generator "off" when DIP #3 is in the up(off) position. When switched to the down

("on") position, the received clock signal (from the remote side) is also used as an internal clock
signal and is transmitted to the user's equipment.

DIP #4: Disable dry contact alarm.
These functions can be initiated from one of four DIP switches accessible from front panel. Under normal

operation, all the switches should be set in "UP" position.

SW1 Internal PCB Dip Switches

There are other eight DIP switches located at the PC board and can not be accessed from front panel. These
switches are usually only used during installation.

SW1-1: Enable signal generators. This switch initiates the built-in Signal Generator function. The unit

will generate a visual signal to verify optic link.

SW1-2: Configure TC1720's interface as a DCE or DTE. Off: DCE On: DTE
SW1-3: Enable RxB. (On dual fiber optic models only)
SW1-4: Async/Sync. Configure unit as Async or Sync. On: Async Off: Sync

Note: DIP Switches SW1-5 through SW1-8 are used for the internal clock generator. If the internal clock
from the TC1720 will be utilized, a clock rate can be selected according to the following table.

O
N

1
2
3
4

5
6
7

SW1-5:

1

0

x

3

2

x

5

4

7 8 9

6

11 12 13

10

x

x

x

14

15

x

DIP

Switches

(SW1)

SW1-6:

x

x

SW1-7:
SW1-8:

8k

9.6k 16k 19.2k 32k 38.4k 56k 64k 128k 256k

Table 1. TC1720 Internal Clock Settings (Internal SW1)

xxxxx

x
x

xxxxx

-5-

x

xxx

1.024M

x

x

x

x

x

x

x

x

2.048M512k

4.096M

Legend:

when the TC1720 is
DCE, on DB37 pin 5
& 23.

X = ON

TC1720

(Optional Dual Optics)

User's Manual

RS-422/449 Termination Resistor

Rev. 1.4

A termination resistor is usually necessary for RS-422 applications. Without proper termination, the error
rate of data transmission may be high due to an “echo” effect on the electrical connection. With the addition
of a termination resistor at the beginning or end of the electrical bus, this echo effect is greatly reduced. The
termination resistors are 100 to 130 ohm resistors located inside the TC1720. Two jumpers, identified as
board locations “JP2” & “JP3,” control the termination resistance on each unit. “JP3” controls the resistance
for the unit’s receiver, while “JP2” controls the transmitter’s resistance. Proper line termination is usually
accomplished by leaving the “JP3” jumper intact at both ends of the link.

Optical Specifications

The following measurements are based on Async data rates of up to 10Mbps.

Transmitter: LED/ELED; typical Launch Power: -19dBm* (1310nm Multimode, @62.5/125µm)

-16dBm* (1310/1550nm Single Mode, @9/125µm)

Receiver: PIN Diode; typical Sensitivity: -34dBm* (1310nm Multimode, @62.5/125µm)

-36dBm* (1310/1550nm Single Mode, @9/125µm)

Loss Budget: 1310nm MM, @62.5/125µm: 15dB

1310/1550nm SM, @9/125µm: 20dB

Distance: 1310nm Multimode, @62.5/125µm: up to 4km distance*

1310nm Single Mode, @9/125µm: up to 50km distance*
1550nm Single Mode, @9/125µm: up to 80km distance*

*Launch power, sensitivity and distance are listed for reference only. These numbers may vary.

-6-

TC1720

RxARxRxB

Optic Signal

TxATxRxARxTxB

RxB

Auto Switch Over

+ -

+ -

Connector

(Optional Dual Optics)

User's Manual

Optical Redundancy (optional)

Rev. 1.4

If optic redundancy was ordered with the unit, figure below applies to its operation. Optic redundancy is used
to prevent the loss of data transmission in the event an optic cable, transmitter, or receiver is broken or
degraded. Should this occur, the secondary optic link & receiver "B" is enabled automatically, thereby
preserving the integrity of the communication. In the meantime, the "Alarm" LED will flash and the buzzer
will sound to indicate a cable breakage.

When the unit is equipped with optic redundancy,
the optic transmitter "TxA" and "TxB" both
transmit the same signal to the remote unit. It is
up to the remote unit to decide whether "RxA" or
"RxB" should be used as the valid incoming optic

Tx

TxA

TxB

Detector

&

Automatic

Switchover

Control

signal. By default, "RxA" is the primary re­ceiver; "RxB" is the stand by backup.

TC1720

Dry Contact Alarm Relay

A terminal block connector at the rear panel
provides for the Dry Contact Alarm Relay. Nor­mally in the OPEN position, any alarm condition
will force the switch to a CLOSED position. This
relay can be used in conjunction with an external
device to signal an alarm condition.

Optic Signal
Detector &

Control

TC1720

TC1720

Power Supply and Rear Panel

The TC1720 consumes very low power. The standard input voltage is from 12VDC and current is 500mA
(max). You may use an external power adapter with the following specifications: 12V DC @800mA (positive
polarity at the left terminal when viewed from the rear panel).

The power plug can be connected into either power jack on the rear panel. Because the TC1720 is equipped
with a built-in power redundancy feature, the "POWER A" or "POWER B" LEDs on the front panel will
illuminate according to which power source the unit is drawing from. If power redundancy is utilized, both
LEDs will light.

For units with the -48V DC power supply option, a DC-to-DC converter is installed inside the unit. The DC
current requirement for the optional -48V DC power supply is @50mA.

PWRAPWR

B

24VDC12VDC
125VDC48VDC

1 19

20 37

ALARMRS-449

Terminal Block Connectors

for Power Supply "A" & "B"

DB37 Male

Figure 4. TC1720's Rear Panel

-7-

Dry Contact Alarm

Relay Connector

TC1720

(Optional Dual Optics)

User's Manual

Chapter 2 - Installation

Rev. 1.4

Unpacking the Unit

Before unpacking any equipment, inspect all shipping containers for evidence of external damage caused
during transportation. The equipment should also be inspected for damage after it is removed from the
container(s). Claims concerning shipping damage should be made directly to the pertinent shipping agencies.
Any discrepancies should be reported immediately to the Customer Service Department at TC Communi­cations, Inc.

Equipment Location

The TC1720 should be located in an area that provides adequate light, work space, and ventilation. Avoid
locating it next to any equipment that may produce electrical interference or strong magnetic fields, such as
elevator shafts, heavy duty power supplies, etc. As with any electronic equipment, keep the unit from
excessive moisture, heat, vibration, metallic particles and freezing temperatures. Installation Procedure
Summary

Installation Procedure Summary

The TC1720 is designed for quick and easy installation. Before installing, however, make sure all DIP
switches are in the up ("Off") position and double-check the polarity at the DC power's terminal block
connector. The installation procedure is as follows:

1. Connect your DTE/DCE Device to the DB37 Connector: Check the Pin Assignments on page 3

and verify your application's data rate. Shielded cable is recommended.

2. Connect the optic cables: Connect the local unit's optic "TxA" to the remote unit's optic "RxA".

Connect the local unit's optic "RxA" to the remote unit's optic "TxA." (do the same for "TxB" and "RxB"
on Dual Optics Models).

3. Connect the power plug: The plug can be connected into either power terminal "A" or "B" (check for

proper polarity). The unit is equipped with power redundancy. By plugging a second power supply to
the spare power terminal, power redundancy is enabled. Verify that the power "A" and/or "B" LED is
illuminated.

4. Turn "On" your device: If your device is a DTE/DCE device, the "TxD" & "TxClk" LEDs on the local

unit should be illuminated, meaning the signal is being transmitted. On the remote unit, the "RxD" &
"RxClk" LEDs should be illuminated, meaning the signal is being received.

5. Check the "Rx-A" LEDs: When a good optic signal is received, the "Rx-A" LED on the corresponding

unit should illuminate. (Check "Rx-B" LED when "Optic TxB" and "Optic RxB" are in use. Dual Optics
model only).

-8-

TC1720

422/

OPTIC

OPTIC

OPTIC

OPTIC

(Optional Dual Optics)

User's Manual

Rev. 1.4

RS 422/449 F/O

MODEM

OPTIC

RxA

OPTIC

RxA

RS 422/449 F/O

MODEM

OPTIC

DTE

DEVICE

RS

422/

449

RS

422/

449

TxA

OPTIC

RxB

TxB

(Dual Optic Models only)

TxA

RxB

TxB

RS

422/

449

RS

449

DTE

DEVICE

Figure 5. Typical Point-to-Point RS-442/449 Application Diagram

After installation is complete, it is an excellent idea to verify and record the optical cable loss. This reading
will both verify the integrity of the system and provide a benchmark for future troubleshooting efforts (see
Chapter 3 - Troubleshooting).

-9-

TC1720

(Optional Dual Optics)

User's Manual

Chapter 3 - Troubleshooting

Rev. 1.4

General

Typically, most problems encountered during installation are related to an improperly wired RS-442/449 cable
or a break in the integrity of the fiber optic link (cable or connectors).

All LEDs are "Off"

If no LEDs are lit on the unit, check the DC power supply, terminal block connector plug, and/or power
source. If the problem persists, contact the Technical Support Department at TC Communications, Inc.

Alarm LED

When there is an alarm condition, the red "ALARM" LED will be lit and the "RxA" LED will also flash to
indicate the optic signal has been lost. The Alarm will also trigger the dry contact relay switch.

Optic Cable Types

Conventionally, fiber optic cable with yellow-colored insulation is used for single mode applications; gray or
orange-colored insulated cable is for multimode use. If multimode cable is used in a single mode application,
the test results could be erroneous and confusing.

Calculating the Loss on the Fiber

The fiber optic link and/or the connectors are frequently the source of communication problems. If problems
are present, check the optic connectors and the integrity of the link first. Ideally, the link should be calibrated
for total loss after the installation has been completed. This will accomplish two things: (1) it will verify that
the total loss of the link is within the loss budget of the device and (2) it will provide a benchmark for future
testing. For example, a system that has been tested as having 6dB of signal loss when installed should not
suddenly test out as having a loss of 10dB. If this were the case, however, the fiber link or connector would
probably be the source of the problem.

These are the reference values we use to calculate the loss on the fiber:

Multimode 1310nm : 2 dB loss per km on 62.5/125µm cable*
Single Mode 1310nm : 0.5 dB loss per km on 9/125µm cable*
Single Mode 1550nm : 0.25 dB loss per km on 9/125µm cable*

*These numbers are listed for reference only. We recommend an OTDR reading be used to measure actual link loss.

RS-442/449 Cable Verification

1. Make sure the electrical signal connections match the pin assignments for the device (refer to page 3

for DCE/DTE pin connections). Verify signal connections by checking the status LEDs on the front panel
of the TC1720. Verify that the pin signal connections match the appropriate LED responses (see Figures
1, 2 & 3).

2. Be sure that all switches are set correctly. All the front panel DIP switches should be in up (off) position.

All the "SW1 Internal DIP Switches" are generally factory configured. However, the clock settings can
be user configured with SW1-5, SW1-6, SW1-7, and SW1-8, to suit the user's timing needs, refer to table
1 on page 5.

Important Warranty Note:

If the need arises for any internal configuration, please contact the Technical Support Department at TC
Communications, Inc @ [phone]. Warranty voided if product seal is broken.

-10-

TC1720

(Optional Dual Optics)

User's Manual

Rev. 1.4

Optic Cable Verification

If the "Rx-A" LED on the front panel is flashing (or off), this is an indication that the optic signal is not being
correctly received. Usually, unsecured fiber optic connectors or faulty cable are to blame. A good
connection is indicated by the "Rx-A" LED on the front panel being solidly lit. This indicates that the receiving
cable is correctly connected to the remote unit's optic "TxA."

On Dual Optics Models, the same applies to "RxB" and "TxB." Dual Optics Models will automatically switch
to optic "RxB" if optic "RxA" is not receiving a valid signal. This automatic switchover enables the user to
verify the "B" fiber connection by simply disconnecting the "A" fiber connection, thereby verifying the optical
redundancy capability of the unit. (Dual Optics is an optional feature).

-11-

TC1720

(Optional Dual Optics)

Chapter 4 - Bench Tests

User's Manual

Rev. 1.4

General

It is highly recommended to conduct a bench test before actual installation. A bench test will allow the user
to get familiar with all the functions and features of the TC1720 in a controlled environment. Knowledge
of the TC1720's functions and features will facilitate installation and troubleshooting efforts later on.

Test Equipment Requirements

End user equipment required for testing:

1. One BERT (Bit Error Rate Tester) test set with a DB37 Female adapter and appropriate interface

module (match pin assignments with the diagrams on page 3).

2. Two short optical cable jumpers with appropriate connectors (ST or FC).

Pre-Installation Tests

1. Make sure the appropriate power supply accompanies the TC1720 unit (see page 7).

2. To verify that the unit functions properly, plug in only the power connector to the terminal (be sure to

observe correct polarity), without having any other cable connections to the unit.

3. On the front panel, the appropriate green "Power A" or "Power B" LED should be illuminated (depending

on whether you plug into the "A" or "B" terminal on the back of the unit). Both lights should be on if you
utilize power redundancy (power is connected to both "A" and "B" terminals on the rear panel).

4. The "ALARM" and "Rx-A" LEDs should be flashing.

5. The "Vcc" LED should be illuminated. Please note: all other LEDs can be in a random state (flashing,

solidly lit, or off) as only upon proper receipt and transmission of a signal will the TC1720 set its LEDs
appropriately for normal operation.

-12-

TC1720

ALARM

DB37 Female

FIBER OPTIC MODEM

(Optional Dual Optics)

User's Manual

Local Electrical Loopback Test

Rev. 1.4

1. Set up the bench test as illustrated in Figure 6 below.

2. Make sure your BERT tester is turned on and configured as an RS-422/499 DTE device if the unit is

DCE.

3. Connect the DB37 female adapter (check pin assignments on page 3) from the BERT tester to the

TC1720’s DB37 male connector (on the rear panel).

4. Set the BERT test set to the same (or as close to the same) data rate as the application you plan to connect

to (typically 19.2Kbps through 128Kbps Synchronous).

5. The data bits should be selected as ‘8 bits’ and the data pattern should be set to ‘2047’ on the BERT

tester.

6. At this point, the following LEDs should be observed on the TC1720 unit: The "TxD," "TxClk," "PWRA

or PWRB," "Vcc," and "ALARM" should be solidly lit. Note, the "ALM" LED will be solidly lit and the
"RxA" LED will be flashing since there is no optical fiber cables connected. All other LEDs should be
off.

7. Now, turn the front panel SW2-2 (LOCLB) dip switch to the down "On" position to enable the Local

Loopback test function.

8. At this point, the tester should indicate a Synchronous signal being received indicating that the RS-422/

449 electrical signal is transmitted and received okay.

9. Verify that the "TxD," "RxD," "TxClk," "RxClk," "ALARM," "PWRA or PWRB," and "Vcc" LEDs are

solidly lit. Note, the "ALM" LED will be solidly lit and the "RxA" LED will be flashing since there is no
optical fiber cables connected. All other LEDs should be off.

You should not see any bit errors. To verify this, inject an error using the BERT tester to see if it will
be recorded by the tester, then verify that no additional errors appear after the user injected error.

10.When done with this test, make sure to return the front panel SW2-2 (LOCLB) dip switch to the up "Off"

position to disable the Local Loopback test function and proceed with other tests.

DC Power Supply

Cable

Male DB37

RS-422/449

ASYNC/SYNC

12VDC@ 500mA

PWR

B

PWR

A

BERT Test Set

with RS-422/449

Figure 6. Local Electrical Loopback Test Connection Diagram

-13-

(Optional)

OPTIC

TxB TxARxB

OPTIC

RxA

TC1720

ALARM

DB37 Female

FIBER OPTIC MODEM

(Optical redundant

DC Power Supply

(Optional Dual Optics)

User's Manual

Local Optical Loopback Test

Rev. 1.4

To perform this local optical test, all the front panel SW2 dip switches should be to the up "Off" position.

1. Set up the bench test as illustrated in Figure 7 below. Make sure to use the correct type of fiber optical

jumper cables (either Single Mode or Multimode according to the specifications of the TC1720s).

2. Make sure your BERT tester is turned on and configured as an RS-422/499 DTE device if the unit is

DCE.

3. Connect the DB37 female adapter (check pin assignments on page 3) from the BERT tester to the

TC1720’s DB37 male connector (on the rear panel).

4. Set the BERT test set to the same (or as close to the same) data rate as the application you plan to connect

to (typically 19.2Kbps through 128Kbps Synchronous).

5. The data bits should be selected as ‘8 bits’ and the data pattern should be set to ‘2047’ on the BERT

tester.

6. At this point, the tester should indicate a Synchronous signal being received indicating that the RS-422/

449 electrical signal is transmitted and received okay.

7. Verify that the "TxD," "RxD," "TxClk," "RxClk," "RxA," "PWRA or PWRB," and "Vcc" LEDs are solidly

lit on the TC1720. Note, the "ALARM" LED will be "Off" since there is optical fiber cable(s) connected.
All other LEDs should be off.

You should not see any bit errors. To verify this, inject an error using the BERT tester to see if it will
be recorded by the tester, then verify that no additional errors appear after the user injected error.

BERT Test Set

with RS-422/449

Cable

(Optional)

TxB

Male DB37

RS-422/449

ASYNC/SYNC

OPTIC

TxARxB

OPTIC

12VDC@ 500mA

PWR

B

RxA

PWR

A

Figure 7. Local Optical Loopback Test Connection Diagram

models only)

-14-

TC1720

ALARM

BERT Test Set

with RS-422/449

FIBER OPTIC MODEM

DC Power Supply

(Optional Dual Optics)

Remote Optical Loopback Test

User's Manual

Rev. 1.4

1. Connect a second TC1720 unit. As with the first unit, from doing the local optical loopback test, follow

the bench test steps on the previous page. When you have completed the local optical loopback test for
the second unit, proceed to the next step.

2. Set up the bench test as illustrated in Figure 8 below.

3. Set the BERT test set to the same (or as close to the same) data rate as the application you plan to connect

to (typically 19.2Kbps through 128Kbps Synchronous).

4. The data bits should be selected as ‘8 bits’ and the data pattern should be set to ‘2047’ on the BERT

tester.

5. Now, on the Local Unit Only, turn the front panel SW2-1 (RMTLB) dip switch to the down "On" position

to enable the Remote Loopback Test function. All other dip switches must be up or Off. On the Remote
TC1720 all dip switches must be up or Off.

6. At this point, the tester should indicate a Synchronous signal being received (if the optical cable and

connectors are good and the cable has been connected properly).

7. Verify the following LEDs on both the Local and Remote TC1720 units:
On the Local unit, the "TxD," "RxD," "TxClk," "RxClk," "RxA," "PWRA or PWRB," and "Vcc" LEDs

are solidly lit. The "ALARM" LED and all other LEDs will be off.
On the Remote unit , the "TxD," "RxD," "TxClk," "RxClk," "RxA," "PWRA or PWRB," and "Vcc" LEDs

are solidly lit. The "ALARM" LED will be in a flashing mode, indicating the unit is diagnostic mode.
You should not see any bit errors. To verify this, inject an error using the BERT tester to see if it will

be recorded by the tester, then verify that no additional errors appear after the user injected error.

8. When done with this test, make sure to return the Local unit's front panel SW2-1 (RMTLB) dip switch
to the up "Off" position to disable to Remote Optical Loopback test function to proceed with other tests.

DB37 Female

Cable

ALARM

Male DB37

RS-422/449 RS-422/449

Local

unit

ASYNC/SYNC

FIBER OPTIC MODEM

(Optional) (Optional)

OPTIC

TxB TxBTxA

RxB RxB

Only

SW2-1 Dip

Down

DC Power Supply

12VDC@ 500mA

PWR

B

RxA

PWR

12VDC@ 500mA

A

Male DB37

PWR

PWR

A

B

Remote

unit

ASYNC/SYNC

OPTICOPTIC

All

SW2 Dip

Up

TxA

OPTIC

RxA

(Optical redundant

models only)

Figure 8. Remote Optical Loopback Test Connection Diagram

-15-

TC1720

ALARM

BERT Test Set

with RS-422/449

FIBER OPTIC MODEM

DC Power Supply

(Optional Dual Optics)

User's Manual

Remote Electrical Loopback Test

Rev. 1.4

1. Set up the bench test as illustrated in Figure 9 below. Make sure all front panel SW2 dip switches on both

the Local & Remote TC1720's are to the up "Off" position.

2. Connect four copper-wire jumpers to short (loopback) the DB37 Male connector on the rear of the

remote unit as follows (these copper-wire connections will loopback the signal at the remote TC1720):

Pin 4 (+SD) to Pin 6 (+RD)
Pin 22 (-SD) to Pin 24 (-RD)

Pin 17 (+TT) to Pin 8 (+RT)

Pin 35 (-TT) to Pin 26 (-RT)

3. Set the BERT test set to the same (or as close to the same) data rate as the application you plan to connect
to (typically 19.2Kbps through 128Kbps Synchronous).

4. The data bits should be selected as ‘8 bits’ and the data pattern should be set to ‘2047’ on the BERT
tester.

5. At this point, the tester should indicate a Synchronous signal being received (if the optical cable and
connectors are good and the electrical cable has been connected properly).

6. Verify that the "TxD," "RxD," "TxClk," "RxClk," "RxA," "PWRA or PWRB," and "Vcc" LEDs are solidly
lit on both the Local and Remote TC1720s. Note, the "ALARM" LED will be "Off" since there are optical
fiber cables connected. All other LEDs should be off.

You should not see any bit errors. To verify this, inject an error using the BERT tester to see if it will
be recorded by the tester, then verify that no additional errors appear after the user injected error.

)

)

D

)

R

(
4

2
n

i
P

o

t
)
D
S

(
2

2
n

i
P

ASYNC/SYNC

T

T

R

(

R

(

6

8

2

n

n

i

i

P

P

o

o

t

t

)

)

T

T

T

T

(

(
5

7

3

1
n

n

i

i
P

P

OPTIC

PWR

B

12VDC@ 500mA

PWR

A

DB37 Female

Cable

Local

ALARM

unit

(Optional)

OPTIC

TxB

)
D
R

(
6
n

i
P
o

t
)
D
S

(
4

DC Power Supply

12VDC@ 500mA

Male DB37 Male DB37

RS-422/449

PWR

PWR

A

B

n

i
P

RS-422/449

Remote

unit

ASYNC/SYNC

FIBER OPTIC MODEM

(Optional)

OPTICOPTIC

RxA RxA

TxBTxA TxARxB RxB

(Optical redundant

models only)

Figure 9. Remote Electrical Loopback Test Connection Diagram

-16-

TC1720

ALARM

RS-422/449

FIBER OPTIC MODEM

DC Power Supply

(Optional Dual Optics)

User's Manual

Bench Test With Built-In Signal Generator

Rev. 1.4

The TC1720 has built-in signal generator to simulate a polling device's incoming electrical signal. The built

-in signal generator is a pulse signal indicated by blinking LED. The flash rate is intentionally reduced for

easy visual confirmation.
The purpose of the Signal Generator Test is to verify the optical connections and the clock signal of the units.

Important Note:

Before proceeding with the Signal Generator test, please read the Warranty Note on page 10.

1. Setup the bench test as shown in Figure 10.

2. At the local TC1720 unit, turn on the "SIG-GEN" by sliding SW1-1 (switch 1 of the "SW1 Internal DIP

Switch") to the right (on) position.

2a. For "Sync" units(SW1-4: disabled "Off"): Turn on the "RMTLB" by pressing down the DIP switches #1

of "Front Panel DIP Switches" on the Local TC1720. The "TxD & RxD," "RTS & CTS," "CD & CD,"
"TxClk & RxClk" LEDs on the local TC1720 should light sequentially from top to bottom. Likewise, the
same flashing LED sequence should be observed on the Remote TC1720 indicating receipt of the local
unit's simulated response.

3. When done with this test, turn off the "SIG-GEN" by sliding SW1-1 (switch 1 of the "SW1 Internal DIP
Switch") to the left (off) position.

DC Power Supply

12VDC@ 500mA

ALARM

Male DB37

RS-422/449

PWR

PWR

A

B

Local

unit

ASYNC/SYNC

FIBER OPTIC MODEM

(Optional) (Optional)

OPTIC OPTIC

TxB

RxB

OPTIC

RxA RxA

Male DB37

Remote

unit

TxBTxA TxA

RxB

ASYNC/SYNC

OPTIC

PWR

B

12VDC@ 500mA

PWR

A

(Optical redundant

models only)

Figure 10. Signal Generator Bench Test Connection Diagram

-17-

Chapter 5 - Component Placement

8k

9.6k

38.4k

1.024M

2.048M

4.096M

5 - 10M

Legend:

X = ON

This table shows the

Internal Clock speed

For Oscillator: 8.192Mhz

TC1720

(Optional Dual Optics)

User's Manual

Rev. 1.4

FPGA configuration
EEPROM

DRY

CONTACT

ALARM

DB37 Male connector

for electrical signal connection

INTERFACE MODULE

FPGA

chip

Trim-pot to adjust optic launch power:
Clockwise to increase optic power;
counter-clockwise to decrease optic power.

U4

(12 - 14VDC) @500mA

POWER B POWER A

+

+

--

TERMINAL

BLOCK

CONNECTORS

JP2

SW1

O
N

1
2
3
4
5
6
7
8

SW2

432

1

F1

F2

fuses

Optic “TxB” (optional)

SW1 Internal DIP Switches
Used to configure TC1720:

to enable the signal generator test,
to change DCE (Off) or DTE (On) device,
to enable secondary optic receiver, and
to select the internal clock rate.
SW1-1: enable signal generators
SW1-2: configure TC1720’s interface as DCE or DTE
SW1-3: enable RxB
SW1-4: enable Async/Sync mode

1

0

SW1-5:

SW1-6:

SW1-7:

SW1-8:

2 3 4

x

x

Optic “RxB (optional)

5

x

x

xxx

Optic “TxA”

6 7 8 9

x

x

x

x

x

x

Optic “RxA”

10

x

x

x

x

when the TC1720 is
DCE, on DB37 pin 5
& 23.

11 12 13 14

x

x

x

x

x

x

x

x

15

x

x
x

x

x
x

x

Figure 11. Component Locations on TC1720's Internal PCB (with optional Dual Optics)

16k 19.2k 32k

56k

-18-

64k 128k

256k

512K

(Optional Dual Optics)

Chapter 6 - Specifications

Data Rates

Asynchronous......................................................................................... Up to 10 Mbps

Synchronous............................................................................................. Up to 5 Mbps

Optical

Transmitter ................................................................................... LED/LASER with AGC

Receiver .......................................................................................................... Pin Diode

Wavelength ....................................................................................... 1310nm Multimode

.............................................................................................. 1310/1550nm Single Mode

Connector .......................................................................................................ST* or FC

Loss Budget** ................................................... 15dB Multimode 1310nm @62.5/125µm

................................................................... 20dB Single Mode 1310/1550nm @9/125µm

Electrical

TC1720

User's Manual

Rev. 1.4

Interface ...................................................................................................RS-422/RS-449

Connector ...................................................................................................... DB37 Male

System

Bit Error Rate ........................................................................................ 1 in 109 or better

Indicators

System status............................ ALARM, PWR A, PWR B, Vcc, Rx-A, Rx-B, USE-B, DTE

Electrical Signal Status .................................................................................... RxD, TxD

Optic Signal Status...................................... TxA, RxB (for Dual Optics, TxB and RxB)

Power Source

Standard.................................................................................. 12VDC @500mA (typical)

Optional .......................... 24VDC, 48VDC, or 115/230VAC with an external power cube

Temperature

Operating ................................................................................................... -10oC to 50oC

..................................................................... Hi-Temp Version (optional) -20oC to 70oC

............................................................ Extreme-Temp Version (optional) -40oC to 85oC

Storage....................................................................................................... -40oC to 90oC

Humidity........................................................................................ 95% non-condensing

Physical (Rackmount Card)

Height ...................................................................................................... (3.53 cm) 1.39"

Width ......................................................................................................(18.13 cm) 7.14"

Depth ......................................................................................................(16.59 cm) 6.53"

Weight ................................................................................................... (192 gm) 5.44 oz

*ST is a trademark of AT&T
**Contact factory for loss budget requirements greater than 20dB (Laser version).

-19-

TC1720

(Optional Dual Optics)

Appendix A

User's Manual

Rev. 1.4

Return Policy

To return a product, you must first obtain a Return Material Authorization number from the Customer
Service Department. If the product’s warranty has expired, you will need to provide a purchase order to
authorize the repair. When returning a product for a suspected failure, please provide a description of the
problem and any results of diagnostic tests that have been conducted.

Warranty

Damages by lightning or power surges are not covered under this warranty.

All products manufactured by TC Communications, Inc. come with a five year (beginning 1-1-02)
warranty. TC Communications, Inc. warrants to the Buyer that all goods sold will perform in accordance
with the applicable data sheets, drawings or written specifications. It also warrants that, at the time of sale,
the goods will be free from defects in material or workmanship. This warranty shall apply for a period of
five years from the date of shipment, unless goods have been subject to misuse, neglect, altered or destroyed
serial number labels, accidents (damages caused in whole or in part to accident, lightning, power surge, floods,
fires, earthquakes, natural disasters, or Acts of God.), improper installation or maintenance, or alteration or
repair by anyone other than Seller or its authorized representative.

Buyer should notify TC Communications, Inc. promptly in writing of any claim based upon warranty, and
TC Communications, Inc., at its option, may first inspect such goods at the premises of the Buyer, or may
give written authorization to Buyer to return the goods to TC Communications, Inc., transportation charges
prepaid, for examination by TC Communications, Inc. Buyer shall bear the risk of loss until all goods
authorized to be returned are delivered to TC Communications, Inc. TC Communications, Inc. shall not be
liable for any inspection, packing or labor costs in connection with the return of goods.

In the event that TC Communications, Inc. breaches its obligation of warranty, the sole and exclusive
remedy of the Buyer is limited to replacement, repair or credit of the purchase price, at TC Communications,
Inc.’s option.

To return a product, you must first obtain a Return Material Authorization (RMA) number and RMA form
from the Customer Service Department. If the product’s warranty has expired, you will need to provide a
purchase order to authorize the repair. When returning a product for a suspected failure, please fill out RMA
form provided with a description of the problem(s) and any results of diagnostic tests that have been
conducted. The shipping expense to TC Communications should be prepaid. The product should be properly
packaged and insured. After the product is repaired, TC Communications will ship the product back to the
shipper at TC's cost to U.S. domestic destinations. (Foreign customers are responsible for all shipping costs,
duties and taxes [both ways]. We will reject any packages with airway bill indicating TC communications
is responsible for Duties and Taxes. To avoid Customs Duties and Taxes, please include proper documents
indicating the product(s) are returned for repair/retest).

-20-