Remote Automation Solutions Bristol 1200 bps PL Modem Owner's manual

CI-1200-PL

Issue: 03/99

BBI 1200 bps - PL

MODEM

BBI 1200 bps - PL

MODEM

Instruction Manual

Bristol Babcock

TB1

TB4

TB3

TB2

JP1C

JP1B

JP1A

BAT

12v

5 1

U10

NOTICE

The information in this document is subject to change without notice. Every effort has been

made to supply complete and accurate information. However, Bristol Babcock assumes no

responsibility for any errors that may appear in this document.

Request for Additional Instructions

Additional copies of instruction manuals may be ordered from the address below per

attention of the Sales Order Processing Department. List the instruction book numbers or

give complete model number, serial or software version number. Furnish a return address

that includes the name of the person who will receive the material. Billing for extra copies

will be according to current pricing schedules.

AccuRate , and ACCOL are trademarks of Bristol Babcock. Other trademarks or

copyrighted products mentioned in this document are for information only, and belong to

their respective companies, or trademark holders.

this manual may be reproduced in any form without the express written permission of

Bristol Babcock.

IMPORTANT! READ INSTRUCTIONS BEFORE STARTING!

Be sure that these instructions are carefully read and understood before any

operation is attempted. Improper use of this device in some applications may result

in damage or injury. The user is urged to keep this book filed in a convenient location

for future reference.

These instructions may not cover all details or variations in equipment or cover

every possible situation to be met in connection with installation, operation or

maintenance. Should problems arise that are not covered sufficiently in the text, the

purchaser is advised to contact Bristol Babcock for further information.

EQUIPMENT APPLICATION WARNING

The customer should note that a failure of this instrument or system, for whatever

reason, may leave an operating process without protection. Depending upon the

application, this could result in possible damage to property or injury to persons. It is

suggested that the purchaser review the need for additional backup equipment or

provide alternate means of protection such as alarm devices, output limiting, fail-safe

valves, relief valves, emergency shutoffs, emergency switches, etc. If additional

information is required, the purchaser is advised to contact Bristol Babcock.

RETURNED EQUIPMENT WARNING

When returning any equipment to Bristol Babcock for repairs or evaluation,

please note the following: The party sending such materials is responsible to ensure

that the materials returned to Bristol Babcock are clean to safe levels, as such levels

are defined and/or determined by applicable federal, state and/or local law regulations

or codes. Such party agrees to indemnify Bristol Babcock and save Bristol Babcock

harmless from any liability or damage which Bristol Babcock may incur or suffer due

to such party's failure to so act.

ELECTRICAL GROUNDING

Metal enclosures and exposed metal parts of electrical instruments must be

grounded in accordance with OSHA rules and regulations pertaining to "Design Safety

Standards for Electrical Systems," 29 CFR, Part 1910, Subpart S, dated: April 16,

1981 (OSHA rulings are in agreement with the National Electrical Code).

The grounding requirement is also applicable to mechanical or pneumatic

instruments that include electrically-operated devices such as lights, switches, relays,

alarms, or chart drives.

EQUIPMENT DAMAGE FROM ELECTROSTATIC DISCHARGE VOLTAGE

This product contains sensitive electronic components that can be damaged by

exposure to an electrostatic discharge (ESD) voltage. Depending on the magnitude

and duration of the ESD, this can result in erratic operation or complete failure of the

equipment. Read supplemental document S14006 at the back of this manual for

proper care and handling of ESD-sensitive components.

Bristol Babcock

1100 Buckingham Street, Watertown, CT 06795

Telephone (860) 945-2200

WARRANTY

A. Bristol warrants that goods described herein and manufactured by Bristol are free

from defects in material and workmanship for one year from the date of shipment

unless otherwise agreed to by Bristol in writing.

B. Bristol warrants that goods repaired by it pursuant to the warranty are free from

defects in material and workmanship for a period to the end of the original warranty

or ninety (90) days from the date of delivery of repaired goods, whichever is longer.

C. Warranties on goods sold by, but not manufactured by Bristol are expressly limited to

the terms of the warranties given by the manufacturer of such goods.

D. All warranties are terminated in the event that the goods or systems or any part

thereof are (i) misused, abused or otherwise damaged, (ii) repaired, altered or

modified without Bristol's consent, (iii) not installed, maintained and operated in

strict compliance with instructions furnished by Bristol, or (iv) worn, injured or

damaged from abnormal or abusive use in service time.

E. THESE WARRANTIES ARE EXPRESSLY IN LIEU OF ALL OTHER WARRANTIES

EXPRESS OR IMPLIED (INCLUDING WITHOUT LIMITATION WARRANTIES AS

TO MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE), AND

NO WARRANTIES, EXPRESS OR IMPLIED, NOR ANY REPRESENTATIONS,

PROMISES, OR STATEMENTS HAVE BEEN MADE BY BRISTOL UNLESS

ENDORSED HEREIN IN WRITING. FURTHER, THERE ARE NO WARRANTIES

WHICH EXTEND BEYOND THE DESCRIPTION OF THE FACE HEREOF.

F. No agent of Bristol is authorized to assume any liability for it or to make any written

or oral warranties beyond those set forth herein.

REMEDIES

A. Buyer's sole remedy for breach of any warranty is limited exclusively to repair or

replacement without cost to Buyer of any goods or parts found by Seller to be

defective if Buyer notifies Bristol in writing of the alleged defect within ten (10) days

of discovery of the alleged defect and within the warranty period stated above, and if

the Buyer returns such goods to Bristol's Watertown office, unless Bristol's

Watertown office designates a different location, transportation prepaid, within thirty

(30) days of the sending of such notification and which upon examination by Bristol

proves to be defective in material and workmanship. Bristol is not responsible for

any costs of removal, dismantling or reinstallation of allegedly defective or defective

goods. If a Buyer does not wish to ship the product back to Bristol, the Buyer can

arrange to have a Bristol service person come to the site. The Service person's

transportation time and expenses will be for the account of the Buyer. However,

labor for warranty work during normal working hours is not chargeable.

Under no circumstances will Bristol be liable for incidental or consequential damages

resulting from breach of any agreement relating to items included in this quotation

from use of the information herein or from the purchase or use by Buyer, its

employees or other parties of goods sold under said agreement.

FACTORY REPAIR SERVICE & REPLACEMENT PARTS

Before you can return an item for repairs, you must first obtain a return authorization number

from us. You may do this by writing to the address below or by calling (860) 945-2200 and asking for

the Customer Service Department. Never ship anything to us without advance clearance as this will

cause confusion and delays.

A copy of this form must be filled out and attached to any item submitted for repair. Maintain a

copy of the completed form for your reference.

Requests for in-warranty repairs must be checked off below when filling out this form. The

warranty conditions are stated on the back of this sheet. All return shipments, whether in or out of

warranty, must be prepaid by the sender. There will be a nominal charge for repair estimates. If you

agree to proceed with repairs, only the repair costs will apply.

Replacement parts or accessories may be ordered from our Watertown, CT address, attention of:

Sales Order Processing Dept., or by calling (860) 945-2200. Be sure to include the parts description,

part number, model number and serial number. All orders are subject to a minimum billing fee.

REQUIRED INFORMATION FOR FACTORY REPAIRS

Model Number Serial Number

Return Authorization Number Return Approved By

Customer Purch. Order No. Date

(Required for all returned equipment)

Requested Return Date

Warranty Repair Request: Yes No

Customer Address:

Bill to: Ship to:

Company Name

Attention of

Street

City, State, Zip

Company Name

Attention of

Street

City, State, Zip

Describe Problem:

Who should we contact if we need additional information?

Name

Phone ( ) Ext.

Ship prepaid to:

Bristol Babcock

Attn. Repair Dept./RA#

1100 Buckingham Street

Watertown, CT 06795

Bristol Babcock

Training

GET THE MOST FROM YOUR BRISTOL

BABCOCK INSTRUMENT OR SYSTEM

Avoid Delays and problems in getting your system on-line

Minimize installation, start-up and maintenance costs.

Make the most effective use of our hardware and software.

Know your system.

As you know, a well-trained staff is essential to your operation. Bristol Babcock offers a full

schedule of classes conducted by full-time, professional instructors. Classes are offered

throughout the year at four locations: Houston, Los Angeles, Orlando and our Watertown,

CT headquarters. By participating in our training, your personnel can learn how to install,

calibrate, configure, program and maintain any and all Bristol Babcock products and realize

the full potential of your system.

For information or to enroll in any class, contact our training department in Watertown at

(860) 945-2385. For Houston classes, you can also contact our Houston office, at (713) 685-

6200. For Los Angeles classes, you can contact our Ontario, CA office at (909) 923-8488.

A Word About Bristol Babcock

For over 100 years, Bristol has been providing innovative solutions for the measurement

and control industry. Our product lines range from simple analog chart recorders, to

sophisticated digital remote process controllers and flow computers, all the way to turnkey

SCADA systems. Over the years, we have become a leading supplier to the electronic gas

measurement, water purification, and wastewater treatment industries.

On off-shore oil platforms, on natural gas pipelines, and maybe even at your local water

company, there are Bristol Babcock instruments, controllers, and systems running year-in

and year-out to provide accurate and timely data to our customers.

Getting Additional Information

In addition to the information contained in this manual, you may receive additional assis-

tance in using this product from the following sources:

Contacting Bristol Babcock Directly

Bristol Babcock's world headquarters are located at 1100 Buckingham Street, Watertown,

Connecticut 06795, U.S.A.

Our main phone numbers are:

(860) 945-2200

(860) 945-2213 (FAX)

Regular office hours are Monday through Friday, 8:00AM to 4:30PM Eastern Time, excluding

holidays and scheduled factory shutdowns. During other hours, callers may leave messages

using Bristol's voice mail system.

Telephone Support - Technical Questions

During regular business hours, Bristol Babcock's Application Support Group can provide

telephone support for your technical questions.

For technical questions regarding Bristol hardware products call (860) 945-2463.

For technical questions regarding software products such as ACCOL Tools, Open BSI

products, or UOI call (860) 945-2265.

For technical questions regarding Bristol's Enterprise Server

and Enterprise Workstation

products, call (860) 945-2286.

The Application Support Group also maintains a bulletin board for downloading software up-

dates to customers. To access the bulletin board, dial (860) 945-2251 (Modem settings: 14.4K

baud maximum, No parity, 8 data bits, 1 Stop bit).

For assistance in interfacing Bristol Babcock hardware to radios, contact Communication

Technologies in Orlando, FL at (407) 629-9463 or (407) 629-9464.

Telephone Support - Non-Technical Questions, Product Orders, etc.

Questions of a non-technical nature (product orders, literature requests, price and delivery

information, etc.) should be directed to the nearest regional sales office (listed below) or to

your local Bristol sales office or Bristol-authorized sales representative.

U.S. Regional Sales Offices Principal International Sales Offices:

Northeast (Watertown) (860) 945-2262 Bristol Babcock Ltd (UK): (011-441) 562-820-001

Southeast (Birmingham) (205) 980-2010 Bristol of Canada: (416) 675-3820

Midwest (Chicago) (630) 571-6052 Bristol Babcock SA Mouy (France): (011-334) 431-1515

Western (Los Angeles) (909) 923-8488

Southwest (Houston) (713) 685-6200

Please call the main Bristol Babcock number (860-945-2200) if you are unsure which office

covers your particular area.

Visit our Site on the World Wide Web

For general information about Bristol Babcock and its products, please visit our site on the

World Wide Web at:

www.bristolbabcock.com

1200 bps - PL Modem Contents / 0-1

CI-1200-PL

BBI 1200 bps - PL MODEMS

TABLE OF CONTENTS

SECTION TITLE PAGE #

1 FEATURES

..............................................................................................................................1

2 DESCRIPTION

........................................................................................................................1

2.1 Modem Component Identification

.........................................................................................2

2.1.1 Modem Interface Connectors

.................................................................................................3

2.2 Communication Terms

............................................................................................................4

2.3 Listing Of Configurable Options

...........................................................................................4

2.3.1 Switch SW1 Settings (8 & 10- Position Versions)

...............................................................4

2.3.2 Modem Interface Board Jumpers

..........................................................................................7

2.3.3 Modem Board Jumper JP1

.....................................................................................................7

3 FIELD WIRING

.......................................................................................................................7

3.1 Two-Wire Private Line Network

............................................................................................7

3.2 Four-Wire Private Line Network

...........................................................................................9

3.3 Point-to-Point Wiring

............................................................................................................10

3.3.1 Two-Wire Point-to-Point System

.........................................................................................10

3.3.2 Four-Wire Point-to-Point System

.........................................................................................................10

3.4 Networks With Two Branches

.............................................................................................12

4 MODEM SETUP PROCEDURE

.........................................................................................12

4.1 Configuration for Private Line & Radio

.............................................................................12

4.2 Lightning Arresters

...............................................................................................................14

5 DIAGNOSTICS

......................................................................................................................14

5.1 Local Analog Loopback Test

.................................................................................................15

5.2 Local Digital Loopback Test

.................................................................................................16

5.3 Remote Digital Loopback Test

.............................................................................................17

5.4 Benchtop Point-To-Point Modem Testing

..........................................................................18

6 SPECIFICATIONS

...............................................................................................................19

6.1 Operating Specifications

......................................................................................................19

6.2 Environmental Specifications

..............................................................................................20

6.3 FCC, FM & IEEE Approvals

................................................................................................20

CI-1200-PL BBI 1200 bps - PL Modem / 1

SECTION 1 - FEATURES

Bell 202T compatibility

Asynchronous operation at 0 to 1200 bps on unconditioned lines

Half Duplex communications on 2-wire line or Full Duplex comm. on 4-wire lines.

Point-to-Point or Multi-drop operation

-40 C to +85 C Operating Temp.

IEC 801-4 Surge Protection

SECTION 2 - DESCRIPTION

The 1200 bps - PL Modem transmits and receives digital data over "Private Line" (PL)

Telephone Networks. The modem transfers data asynchronously and operates half duplex on

two-wire lines, and operates full duplex on four-wire private lines. The modem suports the

Bell 202T modulation scheme.

A typical example of where these modems are used in a PL network is shown in Figure 1.

This network contains four Bristol Babcock Distributed Controllers equipped with 1200 bps

modems operating in a master/slave configuration. During operation, the master com-

municates with each slave (remote) at prescribed intervals to send and receive data. The in-

terval of polling is a function of the application software that is executed by the master

device.

When configured for private line operation, the modem may be operated over 2 or 4-wire

point-to-point (see Figures 8 and 9) or multidropped networks (see Figures 6, 7 and 10).

The modem operates at 1200 baud and is compatible with the following communication

standards:

Table 1 - Standards For PL Networks

Compatible With

Standards:

Comm.

Mode

Pvt. Line

Wiring

Bell 202T Half Duplex Unconditioned 3002 Bell type 2-Wire

Bell 202T Full Duplex Unconditioned 3002 Bell type 4-Wire

The modem's transmitter output, as measured with 600 ohm termination (typical for

telephone lines) is as follows:

Private Line @ 1200 bps (2 or 4-wire) = 0 or -10 dBm (Selectable via SW1)

2 / BBI 1200 bps - PL Modem CI-1200-PL

Figure 1 - Private Line Multidrop Network

2.1 Modem Component Identification

The areas of the modem discussed in this text are highlighted in Figure 2. Interconnection

components include a field wiring terminal block (TB1) for private line connection, an al-

ternate field wiring terminal block (TB2) for private line connection (in lieu of TB1), and a

15-pin header (P1) that plugs into the host device. The modem is comprised of a two board

set, i.e., the small Modem Board and the larger Modem Interface Board. These boards are in-

terfaced via connectors P2 and J3 (not shown). Switch SW1, which is used to configure the

1200 bps PL modem, is located on the bottom of the Modem Board. Jumper JP1, which is

used to configure the modem for 2-wire or 4-wire operation, is also located on the bottom of

the Modem Board while Jumpers JP6 (labeled J6), JP8 (labeled J8), JP1A, JP1B and JP1C,

which are used to configure the BBI (DPC) to modem interface, are located on the Modem

Interface Board.

Note: The following Modem Interface Connectors are not discussed in this

text (as they are not used for PL operation): J1, J4 and , J5.

CI-1200-PL BBI 1200 bps - PL Modem / 3

Figure 2 - 1200 bps - PL Modem Component Identification

2.1.1 Modem Interface Connectors

Modem Interface Board Connectors provide routing for power and ground and all signals

which flow between the DPC and modem or the private line (PL) and modem. The tables

below provide interface information. All I/O is referenced with respect to the Modem In-

terface Board.

Table 2 - Private Line/Radio Interface Connector #1 -TB1

TB1 Pin # Signal Name Description Input/Output

1 T/R_1 (P/L) Transmit/Receive Private Line I/O

2 T/R-2 (P/L) Transmit/Receive Private Line I/O

3 R_1 (P/L Receive Private Line 4-Wire I

4 R_2 (P/L) Receive Private Line 4-Wire I

5 N/A N/A N/A

6 N/A N/A N/A

4 / BBI 1200 bps - PL Modem CI-1200-PL

Table 3 - Alternate Telephone Connector #2 - TB2

P2 Pin # Signal Name Description Input/Output

1 T/R Transmit/Receive I/O

2 T/R Transmit/Receive I/O

3 T1/R1 Receive Private Line 4-Wire I/O

4 T1/R1 Receive Private Line 4-Wire I/O

5 --- --- ---

6 --- --- ---

7 GND Ground ---

8 DTR Data Terminal Ready I

9 RD Receive Data I

10 TD Transmit Data O

Note: TB3 & TB4 are used in conjunction with the RTU 3305. (see Section 4.1)

2.2 Communication Terms

The communication mnemonics used in this text are defined as follows:

TXA - Transmit Analog Signal TXD - Transmit Data CD - Carrier Detect

RXA - Received Analog Signal RXD - Receive Data PL - Private Line

DTR - Data Terminal Ready RTS - Request to Send CTS - Clear to Send

2.3 Listing of Configurable Options

2.3.1 Switch SW1 Settings (8 & 10- Position Versions)

Figure 3 - Switch SW1 (8-Position Version) (Invert modem to view SW1 as shown)

Figure 4 - Switch SW1 (10-Pos. Version) (Invert modem to view SW1 as shown)

SW1-1 = TXA Power Output (into 600 ohms)

ON = 0 dBm (Default)

OFF = -10 dBm

SW1-2 = Antistreaming

ON = Disable after 45 seconds (Note for 8-position SW1, SW1-8 must be ON and

for 10-position SW1, SW1-9 must be ON for Antistreaming)

OFF = No Antistream (Default)

CI-1200-PL BBI 1200 bps - PL Modem / 5

Antistreaming limits the amount of time that the modem puts the carrier onto the line,

and is intended as a fail-safe check. If RTS is continuously active for more than 45

seconds and SW1-2 is ON, the modem will disable its carrier (TXA output will turn off)

and disconnect from the line.

SW1-3 = RXA Signal Level

ON = RXA signal level set for -33dBm or higher (Default) to turn on Carrier

Detect (CD).

OFF = RXA signal level set for -43dBm or higher to turn on Carrier Detect (CD).

SW1-4 and SW1-5 =RTS/CTS Delay Time

Table 4A - RTS/CTS Delay Time (8-Position SW1)

Switch # Config. 1 Config. 2 Config. 3 Config. 4

SW1-4 OFF ON OFF ON

SW1-5 OFF OFF ON ON

Delay

Value

1 ms 16 ms 35 ms

50 ms

(Default)

Table 4B - RTS/CTS Delay Time (10-Position SW1)

Wire

Switched

Carrier

Constant

Carrier

Switch

Switch 9

Soft

Carrier

RTS/CTS

Delay

Time

NO YES YES YES ON ON OFF 50 ms

YES NO YES NO ON ON ON 50 ms

NO YES YES NO ON ON ON 50 ms

YES NO YES NO ON ON OFF 50 ms

NO YES YES YES OFF ON OFF 35 ms

NO YES YES NO OFF ON ON 35 ms

YES NO YES NO OFF ON ON 35 ms

YES NO YES NO OFF ON OFF 35 ms

NO YES YES YES ON OFF OFF 12 ms

NO YES YES NO ON OFF ON 35 ms

YES NO YES NO ON OFF ON 12 ms

YES NO YES NO ON OFF OFF 12 ms

NO YES NO YES OFF OFF OFF 1 ms

NO YES YES NO OFF OFF OFF 12 ms

NO YES YES NO OFF OFF ON 32 ms

YES NO YES NO OFF OFF OFF 1 ms

YES NO YES NO OFF OFF ON 1 ms

Purpose of RTS/CTS Delay

When using two-wire telephone communications, signal echoes can appear on the line

each time the transmission changes direction. These echoes occur when the line amp-

lifiers are switched and there is energy stored in the line from the previous transmission.

6 / BBI 1200 bps - PL Modem CI-1200-PL

Since this energy has not totally decayed, it can interfere with the intelligibility of the

messages being sent from the opposite direction. This problem can be helped by in-

troducing a fixed delay period from the time the modem transmitter is turned ON (RTS

goes ON) until the data transmissions are initiated (CTS goes ON). The delay allows the

echoes to dissipate to a level where they are no longer a problem.

Considerations for RTS/CTS Delay

Although short delays are preferable, they should not be set so short that data quality is

compromised. A good starting point is 50 ms but other values could be selected based on

knowledge of the system. For example, when communicating at 1200 bps over private

lines under a distance of 50 miles, a setting of 16 ms may produce satisfactory results.

Longer distances will usually require settings from 35 to 50 ms.

SW1-6 - 8-Position SW1 = RXA Clamped OFF when RTS is ON

ON = Active

OFF = No Clamp (Default) (RXA in Full Duplex Mode)

SW1-6 - 10-Position SW1 = Switched/Constant Carrier (see Table 5)

ON = Constant Carrier (TXA is ON constantly)

OFF = Switched Carrier (Follows RTS State) (Default)

SW1-7 - 8-Position SW1 = Modem Select

ON = 1200 bps - V.23 (Not Supported)

OFF = 1200 bps - Bell 202T (Default)

SW1-7 - 10-Position SW1 = 2 or 4- Wire Modem Select (see Table 5)

ON = 2-wire half duplex mode

OFF = 4-wire full duplex mode (Default)

SW1-8 - 8-Position SW1 = Soft Carrier Controlled by RTS

ON = Switched Carrier (ON/OFF) controlled by RTS (Default)

OFF = Carrier ON continuously

SW1-8 - 10-Position SW1 = Line Termination (see Table 5)

ON = 600 ohms (point-to-point) (Default)

OFF = None

SW1-9 - 10-Position SW1 = Soft Carrier (900Hz) Turn Off Enable (see Table 5)

ON = Soft Carrier On

OFF = Soft Carrier Off (Default)

SW1-10 - 10-Position SW1 = Spare

Table 5 - DIP Switch Settings Required For Most Applications

SW1-

Function

OFF OFF OFF ON OFF ON OFF 4W Pt. to Pt.

OFF OFF OFF ON OFF ON OFF 4W Multi Pt. Master

ON ON OFF OFF OFF OFF ON 4W Multi Pt. Slave - Rx Term. OFF

CI-1200-PL BBI 1200 bps - PL Modem / 7

Table 5 - DIP Switch Settings Required For Most Applications (Continued)

SW1-

Function

ON ON OFF OFF OFF ON ON 4W Multi Pt. Slave - Rx Term. ON

ON ON OFF OFF ON ON ON 2W Pt. to Pt.

ON OFF ON OFF ON ON ON

2W Multi Pt. Master - Line Term.

ON OFF ON OFF ON ON ON 2W Multi Pt. Slave - Line Term. ON

ON OFF ON OFF ON OFF ON 2W Multi Pt. Slave - Line Term. OFF

Note: SW1-1 and SW1-3 are typically set ON.

2.3.2 Modem Interface Board Jumpers

(see Figures 2 & 5)

Jumper JP8 (labeled J8)

must be set in position 2-3 for private line operation (see Figure 2).

Figure 5 - 33XX - Modem Jumper Configuration

2.3.3 Modem Board Jumper JP1

(see Figure 2)

Jumper JP1 on the Modem Board provides configuration for 2-Wire or Four-Wire operation.

To gain access to JP1, the Modem Board will have to be removed (unscrewed) from the

Modem Interface Board (see Figure 2).

SECTION 3 - FIELD WIRING

The 1200 bps - PL Modem may be used in several types of network configurations which are

described under the subtopics that follow. An application consisting of single master and a

single remote requires only one of the remote connections shown in Figure 6.

3.1 Two-Wire Private Line Network

Figure 6 shows a network that uses the private line for communications. The private line

consists of a two-wire voice-grade line. Since communications are half duplex, only one unit

can be transmitting at any given time. A two-wire private line network can effectively handle

a maximum of five remotes. Any number over this value will adversely affect com-

munications. If more remotes are needed, use the four-wire arrangement of Figure 6.

Private line connections are made to the Transmit/Receive (T/R) terminals of each modem as

shown. Note that these terminals have no polarity designations. This occurs because of the

8 / BBI 1200 bps - PL Modem CI-1200-PL

modem's transformer input circuitry. Therefore, the signals may be wired either way. All

necessary signal routing and bridging between the master and each remote is provided by

the telephone company (see Note at end of Section 3.2).

NOTE

Private lines that run outdoors are subject to lightning strikes. It is essential that lightning

arresters, such as Bristol Babcock, Model 8792-14A, be installed at each location where a

private line enters a building. The grounding terminal of each arrester should also be

connected to a reliable earth ground using #10 AWG wire.

Figure 6 - Connections For Two-Wire Private Line Network

CI-1200-PL BBI 1200 bps - PL Modem / 9

3.2 Four-Wire Private Line Network

Figure 7 shows a network that uses a four-wire private line for communications. The four-

wire system consist of two, two-wire voice-grade lines.

The modem can provide either half-duplex or full-duplex communications when it is set for

four-wire operation. In a four-wire configuration, the transmitted data from a modem is ap-

plied to one pair of lines (T/R terminals), while the received data is applied to the other pair

(R Terminals). These terminals have no polarity designations because of the modem's trans-

former input circuitry. Signals may be wired either way.

Figure 7 - Field Connections for Four-Wire Private Line Network

10 / BBI 1200 bps - PL Modem CI-1200-PL

3.3 Point-to-Point Wiring

A basic point-to-point system consists of a single master and a remote DPC communicating

through modems over a private, two-wire or four-wire line. The modem may be operated in

half duplex or full duplex communication systems.

Figure 8 - Point-to-Point Two-Wire System

3.3.1 Two-Wire Point-to-Point System

A two-wire, point-to-point system is shown in Figure 8. For this basic application, a master

unit communicates with a remote unit (slave). Any Series 3330 to 3380 distributed controller

devices can function as either a master or slave unit if the communication ports have been

properly assigned (see ACCOL II Interactive Compiler Manual for details).

3.3.2 Four-Wire Point-to-Point System

Figure 9 illustrates the field connections for a point-to-point, four-wire system. One pair of

wires carries command data from the master to the remote, while the other pair carries

return data from the remote to the master.

Figure 9 - Point-to-Point Four-Wire System

CI-1200-PL BBI 1200 bps - PL Modem / 11

Figure 10 - Multipoint Private Line Network with Ten Remotes, Two Branches

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Remote Automation Solutions Bristol 1200 bps PL Modem Owner's manual

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