Canoga Perkins 2270 User manual

M o d e m s
Canoga Perkins
2270
Fiber Optic Modem
User Manual

2
Canoga Perkins
Notice!
Canoga Perkins has prepared this manual for use by customers and Canoga Perkins personnel
as a guide for the proper installation, operation and/or maintenance of Canoga Perkins equipment.
The drawings, specifications and information contained in this document are the property of Can-
oga Perkins and any unauthorized use or disclosure of such drawings, specifications and informa-
tion is prohibited.
Canoga Perkins reserves the right to change or update the contents of this manual and to change
the specifications of its products at any time without prior notification. Every effort has been made
to keep the information in this document current and accurate as of the date of publication or
revision. However, no guarantee is given or implied that the document is error free or that it is
accurate with regard to any specification.
Canoga Perkins Corporation
An Inductotherm Company
20600 Prairie Street
Chatsworth, CA91311-6008
[phone]
FAX: [phone]
Web Site: www.canoga.com
e-mail: [email protected]
Copyright 1988, 1990, 1991, 1992, 1996, 1998 Canoga Perkins
All Rights Reserved
2270 Fiber Optic Modem
6910321 Rev. D 5/98

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2270 Fiber Optic Modem
Caution!
This product may contain a laser diode emitter operating at a wavelength of 1300 nm - 1600 nm. Use of
optical instruments (for example: collimating optics) with this product may increase eye hazard. Use of
controls or adjustments or performing procedures other than those specified herein may result in
hazardous radiation exposure.
Under normal conditions, the radiation levels emitted by this product are under the Class 1 limits in 21
CFR Chapter 1, Subchapter J.
Notice!
This device contains static sensitive components. It should be handled only with proper Electrostatic
Discharge (ESD) grounding procedures.

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Canoga Perkins
Table of Contents
Chapter 1 - General ..........................................................................................8
1.1 Equipment Description ................................................................................... 8
1.2 Functions, LEDs and Switches ....................................................................... 8
1.3 2201 Rack Chassis ....................................................................................... 10
1.4 2202 Modem Shelf........................................................................................ 10
1.5 2200R Redundant Modem Card Set ........................................................... 10
1.6 ................................................................ Fiber Optic Versions 10
1.7 Loss Budget .................................................................................................. 11
1.8 Optical Bandwidth......................................................................................... 11
1.9 General Installation ...................................................................................... 11
1.9.1 Fiber Optic Cable and Connectors ................................................................... 11
1.9.2 Initial Unit Testing ............................................................................................. 11
1.10 Sensitivity and Optical Power Switches (HPLaser Version Only) 12
1.10.1 Optical Power Switch (HP Laser Version Only)............................................ 12
1.10.2 Sensitivity Switch (HP Laser Version Only .................................................... 12
1.10.3 Optical Switch Settings (HP Laser Version Only) .......................................... 12
1.11 Switch and Jumper Settings ............................................................................... 13
1.12 Mean Time Between Failures (MTBF) ............................................................. 13
Chapter 2 - Installation ................................................................................ 16
2.1 Unpacking the Unit ....................................................................................... 16
2.2 Standalone Modem Installation ................................................................... 16
2.3 2202 Modem Shelf Installation .................................................................... 16
2.4 Fiber Cable and Connectors ......................................................................... 17
2.5 DC Power ...................................................................................................... 17
2.6 Rack Chassis Installation ............................................................................ 18
2.7 Mode and Rate Selection............................................................................. 18
2.7.1 External Clock Operation ................................................................................. 18
2.7.2 Internal Clock Operation .................................................................................. 18
2.7.3 Asynchronous Operation .................................................................................. 20
2.7.4 Data Rates ........................................................................................................ 20
2.7.5 Data Rate vs. Module Frequency .................................................................... 20
2.7.6 Slave Clock Operation ...................................................................................... 20
2.7.7 Consideration of Propagation Delays ....................................................... 20
Chapter 3 - Data Interfaces........................................................................... 23
3.1 Electrical Data Interfaces ............................................................................ 23
3.2 RS-232C/423 Interface Model -32 .............................................................. 23
3.3 RS-449/422 Interfaces.................................................................................. 23
3.3.1 Model -22 ................................................................................................... 25
3.3.2 Model -H22 ................................................................................................ 25
3.3.3 Model -R2R ............................................................................................... 25
3.4 RS-530 Interface Model -R30 ..................................................................... 26
3.5 T1/E1 Interfaces ........................................................................................... 28
3.5.1 Transparent Bipolar Models -B1, -B2, -B3....................................................... 28

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2270 Fiber Optic Modem
3.5.2 DS1 / T1 Model -T1 ......................................................................................... 30
3.6 TTL/BNC Interface Model -BN .................................................................. 30
3.8 ....................Programmable Buffered Interface  Model P53 32
3.8.1 Generic Interface.............................................................................................. 36
3.8.2 External Station ............................................................................................... 37
3.8.3 Internal............................................................................................................. 38
3.8.4 External ........................................................................................................... 39
3.8.5 DTE Adapter ................................................................................................... 40
3.8.6 Legacy Adapter ............................................................................................... 41
3.9 High-Speed RS-422/Mil-Std 188-114C Interfaces ...................................... 42
3.9.1 Model -TW ....................................................................................................... 43
3.9.2 Model -TW8 ..................................................................................................... 44
3.9.3 Model -T22 ....................................................................................................... 44
3.9.4 Model -T88 ....................................................................................................... 44
3.9.5 Model -D22....................................................................................................... 44
3.9.6 Model -D88....................................................................................................... 44
3.10 Interface Reconfiguration .......................................................................... 46
3.11 Standalone Reconfiguration ....................................................................... 46
Chapter 4 - Modem Operation ................................................................... 47
4.1 Modem Operation ........................................................................................ 47
4.2 Fiber Optics................................................................................................... 47
4.3 Transmit Section ........................................................................................... 48
4.4 Receive Section ............................................................................................ 48
4.5 Full Rate Agility ............................................................................................ 48
4.6 Bit Count Integrity ........................................................................................ 49
4.7 Duty Cycle Tolerance ................................................................................... 49
4.8 Control Signals .............................................................................................. 49
4.8.1 Flow Control ..................................................................................................... 50
Chapter 5 - Troubleshooting ......................................................................... 51
5.1 Diagnostic Procedures.................................................................................. 51
5.2 System Test................................................................................................... 51
5.2.1 Local Loopback Test ........................................................................................ 53
5.2.2 Remote Loopback Test..................................................................................... 54
5.2.3 System Loopback Test ..................................................................................... 55
Chapter 6 - Diagnostic Procedures ............................................................ 56
6.1 2270/2201 Diagnostic Procedures................................................................ 56
6.2 System Test Diagnostic Procedure .............................................................. 56
Chapter 7 - Specifications ............................................................................. 58
7.1 Diagnostic Indicators and Controls ............................................................. 58
7.2 Optical Interface ........................................................................................... 58
7.3 System Electrical .......................................................................................... 59
7.4 Physical Dimensions ..................................................................................... 59
7.5 2270 Fiber Optic Modem Configurations .................................................... 60
Appendix A ..................................................................................................... 61
A.1 Customer Service Department Repair ....................................................... 61
Warranty .............................................................................................................. 61
A.2 Return Policy................................................................................................ 61

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Canoga Perkins
List of Figures
Figure Page
1-1 Front Panel Mode/Rate Switch ...........................................................................................9
1-2 Locations of Various Switches .........................................................................................13
2-1 Model 2202 Standalone Modem Shelf ..............................................................................16
2-2 2201 Rack Chassis Front View with Modems Installed ..................................................19
3-1 2270 Interchangeable Interfaces .....................................................................................23
3-2 Transparent BipolarInterface Connectors ......................................................................29
3-3 Available Strapping Options for Programmable Buffered Interface ................................33
3-4 Board Layout and Modules for Programmable Buffered Interface .................................34
3-5 Programmable Buffered Interface, Model P53, DCE RS-530 .........................................36
3-6 Programmable Buffered Interface, Model P53, External Station ....................................37
3-7 Internal Programmable Buffered Interface, Model P53, RS-530 ....................................38
3-8 External Programmable Buffered Interface, Model P53 .................................................39
3-9 Programmable Buffered Interface, Model P53 [DTE] ......................................................40
3-10 Programmable Buffered Interface, Model P53 [LegacyAdapter] .................................41
3-11 BNC and FourTwinAx Connectors (BJ-77 Type) ..........................................................44
3-12 Five TwinAx Connectors (BJ-77 Type) ...........................................................................45
3-13 Interface Card Installation .............................................................................................46
4-1 2270 Circuit Block Diagram ...........................................................................................47
4-2 Typical High Speed 2270 ModemApplication ..................................................................48
4-3 Data Organization with PWM Optics ..............................................................................49
5-1 System Loopback Test Example From User-End of Fiber Link ........................................51
5-2 Bi-Directional Local LoopbackActive .........................................................................53
5-3 Interface Only Local LoopbackActive .........................................................................53
5-4 Optical Only Remote LoopbackActive .........................................................................53
5-5 Bi-Directional Only Remote LoopbackActive .............................................................54
5-6 Optical at Local End Loopback Active ..........................................................................54
A.3 Advance Replacement Policy ...................................................................... 61
A.4 Warranty....................................................................................................... 62
Electronic Products..................................................................................................... 62
Cable Products ........................................................................................................... 62
Limitations................................................................................................................... 62

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2270 Fiber Optic Modem
List of Tables
Table Page
1-A Available Modem Controls ............................................................................................................. 8
1-B Guaranteed Loss Budgets .............................................................................................................10
1-C 2270 Switch Functions..................................................................................................................14
1-D 2270 Jumper Functions ................................................................................................................15
2-A Operating Mode Selections ...........................................................................................................19
2-B Data Rate Switch Position vs. Oscillator Part Number ................................................................21
3-A RS-232C/423 Signals and Pin Assignments ...............................................................................24
3-B Available Models of RS-449/422 Interfaces .................................................................................24
3-C RS-449 (RS-422) Signals and Pin Assignments..........................................................................25
3-D RS-530 Signals and Pin Assignments..........................................................................................26
3-E RS-530 Jumper Options ...............................................................................................................27
3-F Transparent Bipolar Line Interfaces ............................................................................................28
3-G Line Build Out Settings ................................................................................................................29
3-H CCITT V.35 Digital Interface and PinAssignments ....................................................................31
3-I Delay Times for Programmable Buffered Interface .....................................................................34
3-J Strap Configurations for Programmable Buffered Interface .......................................................35
3-K TwinAx and BNC Supported Signals ............................................................................................42
3-L Model Characteristics ..................................................................................................................42
3-M JumperStrap Options ...................................................................................................................43
3-N Models D22 and D88 Connector PinAssignments ......................................................................45
5-A Loopback Options ..........................................................................................................................52

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Canoga Perkins
Chapter 1 - General
1.1 Equipment Description
The 2270 is a high-speed modem for full-duplex operation over fiber optic cable. It operates syn-
chronously up to 20 Mbps, and asynchronously up to 5 Mbps in the sample-data mode with a 25%
jitter limit. The 2270 is available in rack-mount and standalone configurations. Both are intended to
operate with a variety of electrical interfaces (refer to Section 7.5, 2270 Fiber Optic Modem
Configurations, for a listing of the interface options for the 2270). Refer to Section 3 for detailed
descriptions of available I/O interfaces.
The 2270 has integral System Test and loopback diagnostic modes for performance monitoring.
Various 2270 configurations provide local modem controls, including those listed in Table 1-A. A
limited form of end-to-end control lead operation is also available (refer to Section 4.8).
1.2 Functions, LEDs and Switches
The 2270 standalone modems do not have an on/off switch, since they power up when plugged in.
For 2270 Rack-Mount configurations, a power supply on/off switch is located at the rear of each
power supply assembly on the 2201 Rack Chassis.
An eight-section switch bank, located on the front panel of the 2270 (see Figure 1-1), controls all
operating modes and internal clock rates.
Switch positions 1, 2 and 3 select the internal clock operating rates. Refer to Table 2-B for data
rate switch settings. The rates depend on the crystal option installed. Refer to Section 7.5 for a list
of crystal options available. The -08 crystal is installed as the factory default crystal unless an
alternate crystal is ordered.
Table 1-A. Available Modem Controls
DATA/CLOCK CONTROLS
TRANSMIT DATA REQUEST TO SEND
RECEIVE DATA CLEAR TO SEND
TRANSMIT CLOCK DATA CARRIER READY
RECEIVE CLOCK DATA SET READY

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2270 Fiber Optic Modem
Figure 1-1.
Front Panel
Mode/Rate
Switch
The rate setting determines what rate the modem will operate at if set to the Internal Clocking
Mode or the rate used when a modem set to the Slave Clocking Mode is set for local loopback.
The modes are:
External Clock
Internal Clock
Slave Clock
Flow Control
Alternate Loopback Functions
Switch positions 4, 5 and 6 select the clocking mode for the modem as described in Section 2.7
and shown in Table 2-A.
Switch position 7 selects whether the RTS input controls flow control through the modem (Open =
no flow control, Closed = flow control enabled). Refer to Section 4.8.1.
Switch position 8 selects the normal or alternate loopback mode as shown in Table 5-A of the
Troubleshooting section.
Indicator lights are provided for Power On, Optical Receive and Transmit data activity, Interface
Receive and Transmit data activity, and for Loopback On. All of these indicators are located on the
front panel, for both standalone and rack-mount versions.
The loopback switch on the front panel is used to activate the built-in system test or to select
either a Local or Remote loopback function. Use of this switch is outlined in Chapter 5, Trouble-
shooting.
The electrical interface connection and fiber optic connections are made at the rear of the modem.
The HI/LO optical power switch is also located there.
There is also a HI/LO switch for the optical receiver, used to select its sensitivity. Operating this
switch in the LO position may be necessary under certain low-loss conditions (refer to Section
1.9).

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Canoga Perkins
1.3 2201 Rack Chassis
The 2201 Rack Chassis is designed to accommodate up to ten 2200 series modems.
It offers a variety of features, including local audible/visible and remote power failure alarms, op-
tional redundant power supply, and the ability to allow modem removal from the chassis without
powering down the entire system. Refer to the 2201 Rack Chassis / 2200R Redundant Modem
Card User Manual for more details.
1.4 2202 Modem Shelf
The 2202 Modem Shelf accommodates one or two standalone 2200-series modems. It is de-
signed to fit easily into a 19-inch equipment rack. The modems can be secured side-by-side in the
shelf. Refer to the 2202 Modem Shelf User Manual for more details.
1.5 2200R Redundant Modem Card Set
A redundant board set, consisting of two 2270 Modems and a 2200R Modem Card, uses three
slots of the 2201 Rack Chassis. It enables a user to incorporate a fully redundant fiber optic link
with 2270 Modems. The combination of the three boards provides redundant operation for data
rates up to 20 Mbps. Redundancy is not available for standalone models.
The 2200R provides the redundancy controller and signal switch for a redundant board set. The
2200R is equipped with keyed-ribbon cables and a modem interface (RPB) extender for easy
installation. Refer to the 2201 Rack Chassis / 2200R Redundant Modem Card User Manual for
more details.
1.6 Fiber Optic Versions
Three fiber optic versions provide solutions to virtually any fiber-optic plant, including 50/125 or
62.5/125 multimode and 8-10/125 single mode. Table 1-B summarizes the three fiber-optic
versions. Table 1-B. Guaranteed Loss Budgets
Fiber Size
Optics Option 8/10 50 62.5 Min. Launch
SM MM MM Power dBm
850 nm LED N/A 2 6 -14
1310 nm LP Laser 10 10 10 -8
1310 nm HP Laser 15 15 15 -6
[Typical loss budgets are 2 dB higher]
N/A = Not Applicable

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2270 Fiber Optic Modem
1.7 Loss Budget
The maximum possible distances with either standard or long distance versions is dependent on
the overall power loss over the fiber optic link. This is called the link loss. The launch power for the
modem is compared with receiver sensitivity. The determination of the difference is the loss budget
(refer to Table 1-B). To insure normal operation over a long term, the link loss should be at least 3
dB less than the loss budget for the modem.
For example, consider a data link 7 kilometers long using 50/125 optical fiber that has a measured
power loss of 9 dB, and a patch panel connector loss of 3 dB, for a total link loss of 12 dB.
The minimum launch power of the 2270 High Power (HP) laser version is -6 dBm in high-power
mode, and the worst-case receiver sensitivity is -21 dBm. The guaranteed loss budget is 15 dB.
Subtracting the link loss (12 dB) from the loss budget (15 dB) leaves a margin of 3 dB -- is within
the suggested limit.
NOTE: Optical power measurements for the 2270 are sensitive to the data rate. All mea-
surements quoted are for a 20 Mbps data rate.
1.8 Optical Bandwidth
The 2270 requires nearly 70 MHz of optical bandwidth. As a result, the specified fiber optic cable
must provide this bandwidth at the required distance.
For example, if 500 MHz/km fiber is used, this bandwidth requirement will limit the end-to-end
distance to 7 km (70 MHz multiplied by 7 km = 490 MHz).
1.9 General Installation
1.9.1 Fiber Optic Cable and Connectors
The 2270 can be used with virtually any size of multimode or single mode fiber optic cable includ-
ing 50/125, 62.5/125 and 8-10/125.
The proposed fiber optic cable must provide adequate bandwidth and power loss characteristics
for the intended modem link.
Fiber optic connectors terminated on the cable must match those terminated on the modem.
CAUTION:
It is important to keep all connectors free of water, dust, dirt, etc. When not in use, the
connectors should be covered with protective plastic caps.
1.9.2 Initial Unit Testing
The following is a basic list of check points to consider:
•Have you set your optical power and receiver sensitivity switches correctly for the
loss of the fiber optic link?
•Are the fiber optic cables marked correctly? Connect the Tx cable to the Tx connec-
tor, the Rx cable to the Rx connector. If System Test fails, try swapping cables at one
end of the link.

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Canoga Perkins
•Are you using the correct clock mode (internal/external) for synchronous trans-
mission?
•Have the modems mode and rate switches been set properly? (The 2270 is set to the
external clock mode at the factory.)
•If you have problems after carefully checking these items, turn to Chapter 5, Trouble-
shooting.
1.10 Sensitivity and Optical Power Switches (HP Laser
Version Only)
A dual-section switch block is located between the transmit and receive optical connectors (see
Figure 1-3). The section nearest the transmit connector controls the optical transmit power level.
The section nearest the receiver controls the receiver sensitivity. For both switch functions, ON
selects HI and OFF selects LO. For standalone modems, ON = UP and LO = DOWN; for rack
mount modems, ON = RIGHT and LO = LEFT. This feature is only required for the HP laser fiber-
optic version. These switches are not provided in the other fiber-optic versions.
1.10.1 Optical Power Switch (HPLaser Version Only)
The Optical Power Switch (TX POWER) provides two settings for optical transmission levels. The
LO switch setting is intended for use with short fiber optic lengths, i.e., a cable and connector
power loss total of less than 10 dB. The HI switch setting is intended for longer cable runs, up to
the maximum power loss budget.
1.10.2 Sensitivity Switch (HPLaser Version Only
The Sensitivity Switch (RX SENS) provides two settings for optical receiver sensitivity. The LO
switch setting is intended for short fiber lengths in conjunction with LO optical power at the other
end. The LO setting must be used with a fiber link loss of 5 dB or less.
1.10.3 Optical Switch Settings (HPLaser Version Only)
The proper setting of the Optical Transmit Power and Optical Receive Sensitivity Switches are
based on the loss measured on the fiber at a wavelength of 1300 nm. The 2270 should be used as
an optical power source when performing these measurements.
The loss on the fiber link determines the setting of the Tx Power Switch at the transmitting end and
the Rx Sensitivity Switch at the receiving end. It is important to remember that the switch settings
are determined separately for each fiber in the pair.
When operating the modem at rates above 6 Mbps, the HI/HI setting can always be used. HI/HI
refers to HI Tx power and HI Rx sensitivity. If the modem is to be operated below 6 Mbps, or if the
application requires full rate agility (without changing switch configuration) that extends below 6
Mbps, then the settings listed below should be followed.
TX PWR RX SENS MIN LOSS MAX LOSS
LO LO 0 5
LO HI 5 10
HI LO 10 13
HI HI 13 15

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2270 Fiber Optic Modem
These settings give minimum and maximum losses for each of the four possible switch combina-
tions. There is overlap between these ranges that is guaranteed to meet or exceed ±1.0 dB from
the transition points.
The performance of every modem is guaranteed to fit the parameters given above. Some modems
may significantly exceed these performance limits, but reliable operation and unit interchangeabil-
ity is not guaranteed outside of these limits.
1.11 Switch and Jumper Settings
See Figure 1-2 for the location of specific switches and jumpers. Tables 1-C and 1-D summarize
the functions of the 2270s switches and jumpers.
1.12 Mean Time Between Failures (MTBF)
The 2270s Mean Time Between Failures (MTBF) figure, 62,500 hours (calculated) has been
determined from calculations that are similar to MIL-217E. It assumes a Ground Benign environ-
ment and excludes failures which are not service-affecting. This MTBF figure is for a Rack-Mount
2270 with a MIL-STD 188-114C interface (Model 2270-R-TW8-11-08-0).
Figure 1-2.
Locations of
Various Switches

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Canoga Perkins
Table 1-C. 2270 Switch Functions
LOOP TEST switch on Front Panel (described in Section 5, Troubleshooting).
LOC position will activate a local interface loopback.
REM position will activate a System Test and control the state of the far-end loopback.
OFF position is for normal transmission.
TRANSMIT OPTIC POWER switch on Rear Panel (described in Section 1.9).
HI position is used for link losses from approximately 10 dB and greater.
LO position is used for link losses below 10 dB.
RECEIVER SENSITIVITY switch on Rear Panel (described in Section 1.9).
See NOTE 1
The position of this switch is dependent on both the loss of the Rx link and the position
of the Tx optical power switch on the modem at the other end.
CLOCK RATE switches on Front Panel (described in Section 2).
Switches 1-3 control both the internal clock rate and the System Test rate. The rate is
also dependent on the frequency of the installed oscillator.
CLOCK MODE switches on Front Panel (described in Section 2).
Switches 4-6 control the transmitter clock mode (external/slave/internal).
Switch 7 controls the transmitter sensitivity to RTS used for flow control.
Switch 8 enables selecting an alternate loopback method (refer to Section 5 for
Loopback options).
NOTE 1: Power should be cycled after changing switch. The unit must be powered down
whenever a setting is changed.

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2270 Fiber Optic Modem
Table 1-D. 2270 Jumper Functions
SIGNAL GROUND controls connecting circuit ground to the chassis.
CHASSIS connects them together.
FLOAT isolates the two grounds.
Factory Setting = FLOAT
SCT POLARITY controls the transmit clock output.
NORM is always used for low data rates for proper clock phasing.
INV may be needed for internal clock or slave clock modes operating high data rates
if the DTE loop has long delays.
Factory Setting = NORM
TEST controls the built-in test pattern checker.
ON allows System Test loopback to be activated and Remote Loopback control.
OFF defeats pattern loopback for System Test and disables any Remote Loopbacks.
Factory Setting = ON
ALT A and ALT B allow alternate loopback methods to be selected. If the front panel alternate
loopback switch is also considered, there are eight possible loopback responses for
each end of the link.
ALT A affects Local Loopback, depending on the ALT loopback switch.
Factory Setting = OFF
ALT B affects Remote Loopback, depending on the ALT loopback switch.
Factory Setting = OFF
EIADSR allows a proper DSR signal to connect to the interface.
ON connects the signal through interface.
OFF disconnects the signal from the interface. Only the DS1/T1 interface requires
this selection.
Factory Setting = ON

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Canoga Perkins
Chapter 2 - Installation
2.1 Unpacking the Unit
Each 2200 Series Modem is shipped factory tested, and packed in a protective carton. Unpack
the unit and retain the shipping carton and protective packing for reuse in the event it is necessary
to return the modem to the factory.
To assure proper operation of the modem, please inspect it and its shipping carton carefully for
damage. If damage is sustained to the unit, immediately file a liability claim with the freight carrier.
Canoga Perkins is not liable for damage in shipment
2.2 Standalone Modem Installation
Installing the standalone version of the 2270 is straightforward. It should be located conveniently to
the operator. The electrical and optical cables should be isolated from foot traffic to prevent pos-
sible damage.
For AC-powered units, the attached power supply for the standalone is a wall-type transformer. It
should be plugged into a standard AC wall outlet that incorporates a ground line. A POWER ON
switch is not provided as the modem is powered when the unit is plugged in.
2.3 2202 Modem Shelf Installation
Two 2270 standalone modems may be installed in an equipment rack when using the 2202 Mo-
dem Shelf. The modems may be placed side-by-side on the shelf after the shelf is mounted in the
equipment rack (see Figure 2-1).
For a more secure assembly, two screws are provided to secure the modems to the shelf prior to
installing the shelf in the rack.
First, on the modem that will be mounted on the left side of the shelf, remove and discard the
center cover attachment screw on the left side. Position the modem so that the empty hole lines
up with the one on the left side of the shelf.
Next, using one of the longer screws provided, mount the modem from the outside by threading
the screw through the 2202 shelf and into the cover screw hole in the modem.
Figure 2-1.
Model 2202
Standalone
Modem Shelf

17
2270 Fiber Optic Modem
Repeat this procedure for the second modem using the center cover retaining screw on the right
side of the modem. After the modems are secure, you can mount the shelf into the equipment
rack.
NOTE: Depending on accessibility, it may be necessary to connect the fiber cables and
interface cables before mounting the 2202 shelf in the equipment rack.
NOTE: The modem must always be removed from the 2202 shelf, and its top cover re-
moved, to access any switches inside the case.
2.4 Fiber Cable and Connectors
The proposed fiber optic cable must provide adequate bandwidth and power loss characteristics
for the intended modem link. Furthermore, the terminated cable must match the connectors on
the modems: typically, ST.
The connectors on the fiber optic cable, when supplied by Canoga Perkins, are marked Tx and Rx,
and should be connected to matching connectors on the modem. That is, Tx to Tx, and Rx to Rx.
This will link the Rx of the local modem to the Tx of the remote modem, and the Tx of the local
modem to the Rx of the remote modem.
The connectors are clearly marked as to their function, either Transmit (Tx) or Receive (Rx), on the
rear panel of the 2270 standalone units, and on the rear of the 2201 Rack Chassis.
NOTE: Keep all connectors free of water, dust and dirt. Cover them and the cable ends
with plastic caps when they are not mated.
The 2270 can be used with most popular sizes of multimode and single mode optic cable, includ-
ing 8-10/125, 50/125 and 62.5/125.
NOTE: When using 85/125 or 100/140 micron fiber optic cable, an in-line attenuator may
need to be installed between the 2270 and the Receive (Rx) fiber optic cable for proper
modem operation on short links.
2.5 DC Power
A DC-powered version is available for use with a nominal ±48 VDC source (±36 to ±72 VDC @
.5A). Units are supplied with a 5-foot, three-wire cable terminated with a three-pin Molex connector
(Part Number [P/N] 19-09-1036; female pins P/N 02-09-1119). The mating connector is Molex P/N
19-09-2036 (with male pins P/N 02-09-2118).
Power input pin designations are:
Pin # Signal
1 (odd shape) +Vin (RED)
2 Chassis (EARTH)
Ground (WHITE)
3 -Vin (BLACK)
The DC/DC converters isolate input and output so that either polarity DC input can be used.
Normally, Pin 2 (Chassis Ground) is connected to one of the two voltage pins. Protection diodes
on the converter board prevent damage from input polarity reversal. Fuses are soldered in place to
protect the modem from excessive voltage inputs.

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The outside case of the DC-powered modems will run warmer to the touch than the corresponding
AC-powered units. This is because the cover is used as a heat sink for the DC/DC converter.
2.6 Rack Chassis Installation
The 2201 Rack Chassis is designed to accommodate up to ten 2270 modems; see Figure 2-2.
The 2201 will fit into a standard 19-inch equipment rack. Tabs are provided on each side of the unit
and are predrilled for standard spacing. For further details, refer to the 2201 Rack Chassis / 2200R
Redundant Modem Card User Manual.
2.7 Mode and Rate Selection
NOTE: The switch notation standard for mode and rate is the following: Closed = ON,
Open = OFF.
The 2270 has three basic clock operating modes: External, Internal and Slave. These allow the
modem, in combination with the Internal Polarity Option jumper, to be configure for a wide range of
applications.
Asynchronous operation is accomplished by setting the modem to Internal Mode and oversampling
the data (refer to Section 2.7.2, Internal Clock Operation).
The operating mode is selected by setting positions 4, 5 and 6 of the eight-section switch bank on
the front panel. Table 2-A lists the modes and the switch positions. The switch positions are
numbered from left to right (1 to 8).
2.7.1 External Clock Operation
The modem can be set to accept an external clock by closing switch position 4 of the switch block
on the front panel. Leaving switch positions 5 and 6 open will ensure that the transmit clock output
is clamped.
2.7.2 Internal Clock Operation
The modem can be set to provide an oscillator-derived clock to the DTE by closing switch position
6 of the eight-section switch bank on the front panel. Switch position 5 must be left open. Refer to
Section 2.7.4 for information on Data Rates. Refer to Section 2.7.7 regarding switch position 4.
NOTE: For SCT Polarity, refer to Figure 1-3 and Table 1-E; refer to Section 2.7.7 for Con-
sideration of Propagation Delays.

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2270 Fiber Optic Modem
Figure 2-2.
2201 Rack Chassis
Front View
with Modems
Installed
Table 2-A. Operating Mode Selections
Internal DIP Switches
SCT Polarity (C) Closed (O) Open
Jumper 4 5 6 Operating Mode
NORM C O O External Clock Mode (SCT suppressed)
NORM O C X Slave Clock Mode (SCT=Receive Clock)
X=DIP switch position 6 is dont care
INV O C X Slave Clock Mode (SCT=Receive Clock Inverted)
NORM C C X Slave Clock Mode (SCT returned on Ext Clk leads)
NORM O O C Internal Clock Mode Mode (SCT=Internal Clock)
INV O O C Internal Clock Mode Mode (SCT=Internal Clock Inverted)
DIP switch position 5 must be Open
NORM C O C Internal Clock Mode Mode (SCT returned on Ext Clk leads)

20
Canoga Perkins
2.7.3 Asynchronous Operation
The 2270 can operate in the data-only asynchronous mode by setting the Clock Mode to INTER-
NAL and the Clock Rate to the highest frequency setting (switch positions 1-3 all closed).
This allows for a maximum asynchronous rate of one-quarter of the internal clock frequency. For
example, if a 2200-C-08 oscillator is used, the maximum frequency is 20 Mbps, and the highest
asynchronous data rate would be 5 Mbps. This maximum is based on the assumption that a
maximum of 25% peak-to-peak jitter is allowable in the received data signal.
This particular configuration is called SampledAsynchronous Transmission. It requires configur-
ing the modem for internal clock and connecting data signals to the normal data input/output pins.
2.7.4 Data Rates
The maximum data rate permissible depends on the type of interface used. Only the special high-
speed interfaces can be operated above 10 Mbps.
Data rate selection for the 2270 Modem is accomplished by using the front panel switches (see
Figure 1-1). Table 2-B provides a data rate table for use in selecting a specific rate in relation to the
crystal oscillator factory-installed in the modem. The oscillator frequency is marked on the case of
the crystal. Special oscillator frequencies may be requested, if needed.
2.7.5 Data Rate vs. Module Frequency
If a high-speed interface is exchanged for a low-speed version, or vice versa, it may be necessary
to make an oscillator change on the main modem circuit board. Table 2-B lists the standard
oscillators, or you may contact the factory for application assistance.
2.7.6 Slave Clock Operation
The slave clock mode may be selected by closing switch position 5 on the front panel eight-
section switch bank. This will use the 2270s optical received clock as its transmit clock output.
The setting of switch position 6 has no effect. Refer to Section 2.7.7.2 regarding switch position 4.
The System Test feature will function with a modem configured for slave clock operation. However,
the user must be aware of the following limitation: If the System Test is enabled, a modem
configured for slave clock will provide the System Test timing to the user as receive and transmit
clock. This could cause a potential problem, since the System Test timing may not be at the
correct data rate for the user device.
A solution to this problem is selecting an oscillator module which allows selecting Internal/Test
clock equal to the data rate of the user devices.
NOTE: The 2270 Modem will not pass data with an external optical loopback when con-
figured for slave clock operation.
2.7.7 Consideration of Propagation Delays
Whenever the modem is sending a transmit clock to the DTE, it is important to understand the
effect of the time required for that clock to propagate from the modem to the DTE.
Clock-to-Data phasing is particularly important in any synchronous data link. The modem ex-
pects the data to be valid (unchanging) at the point in time when the clock transitions to clock the
data.