o 15.838 Class B computing device: information to user.
This equipment generates and uses radio frequency energy and if not installed
and used properly, that is, in strict accordance with the manufacturer's
instructions, may cause interference to radio and television reception. It has
been type tested and found to comply with the limits for a Class B computing
device in accordance with the specifications in subpart J of Part 15 of FCC
Rules, which are designed to provide reasonable protection against such
interference in a residential installation. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does
cause interference to radio or television reception, which can be determined by
turning the equipment off and on, the user is encouraged to try to correct the
interference by one or more of the following measure:
Reorient the receiving antenna
Relocate the computer with respect to the receiver
Move the computer away from the receiver
Plug the computer into a different outlet so that computer and receiver are
on different branch circuits.
If necessary, the user should consult the dealer or an experienced
radio/television technician for additional suggestions. The user may find the
following booklet prepared by the Federal Communications Commission
helpful:
"How to Identify and Resolve Radio-TV Interference Problems".
This booklet is available from the U.S. Government Printing Office,
Washington, DC 20402, Stock No. 004-000-00345-4.
Warning-When connecting this device to your computer,
shielded interface cables must be used.
MFJ ENTERPRISES, INC.
Model MFJ-1270C/1274C
Packet Radio Controller
Revision 10
SYSTEM MANUAL
Fourth Edition
(c) Copyright 1993, MFJ Enterprises, Inc.
i
TNC 2 SOFTWARE SOURCE CODE and TNC FIRMWARE
Copyright (c) 1985 - 1993
Systek
MFJ-1270C/1274C SOFTWARE SOURCE CODE and FIRMWARE
Copyright (c) 1993
MFJ Enterprises, Inc.
All rights reserved.
Reproduction or translation of any part of this work beyond that permitted by
Sections 107 or 108 of the 1976 United States Copyright Act (or its legal
successor) without the express permission of the copyright owner is unlawful
except as noted below. Requests for permission to copy or for further
information should be addressed to MFJ Enterprises, Inc. P. O. Box 494,
Mississippi State, MS 39762, USA.
The information contained in this document has been carefully checked and is
believed to be entirely reliable. However, no responsibility is assumed for
inaccuracies. MFJ Enterprises, Inc. reserves the right to make changes to any
product to improve reliability, function or design without obligation to
purchasers of previous equipment. MFJ Enterprises, Inc. does not assume
any liability arising out of the application or use of any product or circuit
described herein; neither does it convey any license under its patent rights to
others.
ii
MFJ-1270C/1274C MANUAL TABLE OF CONTENTS
TABLE OF CONTENTS
TABLE OF CONTENTS.........................................................................iii
INTRODUCTION....................................................................................1
Items supplied with MFJ TNC package ......................................2
Optional items available for the MFJ TNC .................................3
COMPUTER INTERFACING .................................................................4
MFJ Terminal Software Starter Packs.........................................4
Computer Interfacing with MFJ Starter Packs...............5
Computer Interface without MFJ Starter Pack...............5
Serial Port Signals......................................................................5
Computers with Specific Serial Interfaces.....................7
Apple Macintosh.............................................7
Commodore C64, C128 and VIC-20 ...............8
IBM PCjr........................................................9
Radio Shack Color Computer..........................9
Radio Shack Model 100/102 and NEC 8201....9
IBM PC/XT/AT/386/486 and compatibles
Computer........................................................10
Other Computers with Non-standard Serial Ports..........12
Terminal Software Requirements ...............................................12
Apple Macintosh ..........................................................13
Apple II, II+, IIe, IIc.....................................................13
Commodore C64, C128 and VIC-20.............................13
IBM PCjr......................................................................14
IBM PC and Compatible Computers.............................14
Radio Shack Color Computer........................................15
Radio Shack Model 100/102 and NEC 8201.................15
MFJ TNC Serial Port Pin Functions ..........................................15
Computer Baud Rate ..................................................................16
Verifying Serial Port Operation..................................................17
RADIO INTERFACING..........................................................................20
MFJ TNC Radio Port.................................................................20
Radio Port Connection ..................................................21
Handheld Radio Connection .........................................21
RADIO INTERFACING METHODS.........................................23
Method 1: Direct Connection to Microphone and
Speaker.........................................................................23
Transmit Audio Level Adjustment for
Method I Interface...........................................24
Setting the Receiver Audio Input Level .........................25
iii
MFJ-1270C/1274C MANUAL TABLE OF CONTENTS
Method 2: Accessory Jack or Interface Box
Connection...................................................................25
Transmit Audio Level Adjustment for
Interface Method II .........................................27
Receiver Audio Setting....................................28
Monitor Speaker Connection ........................................29
GETTING STARTED .............................................................................30
First Steps..................................................................................30
Basic Parameters Setup.................................................31
Serial Port Configuration............................................................31
Parity and Word Length................................................32
Echos............................................................................33
New Lines and Line Wrapping .....................................33
Tuning Indicator (MFJ-1274C) ..................................................34
PACKET OPERATION............................................................34
VHF Packet ..................................................................34
A Connecting and Disconnecting Exercise......35
Digipeating.....................................................37
Unsuccessful Connections...............................38
Monitoring Channel Activity ..........................39
Your First Packet QSO....................................40
Starting the QSO.............................................41
Digipeating.....................................................42
Monitoring on the Air.....................................43
Special Input Characters...............................................43
HF Packet Basic Operation ...........................................46
HF Packet Operation Hints:.............................47
FAX OPERATION ....................................................................47
FAX FREQUENCY......................................................48
FAX STATION FREQUENCIES....................49
Other FAX Frequencies ..................................49
ADVANCED PACKET OPERATION.....................................................50
Special Characters......................................................................50
Packet Operating Modes ..........................................................................52
Command Mode.........................................................................52
Entering Data-Transfer Modes......................................53
Converse Mode .............................................................54
Transparent Mode ........................................................56
Flow Control..............................................................................57
XON/XOFF Flow Control.............................................58
Hardware Flow Control ................................................59
iv
MFJ-1270C/1274C MANUAL TABLE OF CONTENTS
Type-in Flow Control ...................................................59
Detail VHF Packet Operation.....................................................60
Station Identification ....................................................60
Automatic Operations...................................................61
Unattended Operations .................................................62
Packet Formatting.........................................................62
Packet Timing Functions..............................................64
Transmit Timing.............................................64
Packet Timing.................................................65
Radio Baud Rate .............................................66
Special Protocol Times....................................67
Monitor Functions ......................................................................68
Real-Time Clock and Time Stamping.........................................70
Multi-Connect Guide..................................................................70
Setting the MFJ TNC to Normal Operation...................70
How to Invoke Multi-Connect?.....................................71
Easy-Mail Mailbox .....................................................................72
Set Up your Easy-Mail Mailbox....................................72
Mailbox Operation........................................................78
Additional Mailbox Features...........................83
Forwarding........................................83
Eliciting Reverse Forwards ................84
Remote Heard Log.............................84
Chat Mode: .......................................85
Page SYSOP .....................................85
Remote SYSOP.................................85
Mailbox CText..................................85
Idle Timeout......................................85
Abort:................................................86
Mailbox Messages......................................................................86
Slotting and Acknowledgment Priority.....................................................88
Description.................................................................................89
New Parameters............................................................90
Other Related Parameters .............................................93
Initial Parameter Settings Summary..............................94
What to Expect.............................................................95
Packet Picture Transfer ..............................................................96
Receiving Packet Pictures on Printer.............................97
Packet Picture transfer to the computer screen ..............97
Detail HF Packet Operation........................................................98
Radio Setup for HF Packet Operation............................98
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MFJ-1270C/1274C MANUAL TABLE OF CONTENTS
HF Packet Operation ..................................................................102
MFJ TNC KISS MODE AND HOST MODE .............................109
KISS Interface for TCP/IP ............................................109
OPERATION COMMANDS ...................................................................111
Entering Commands...................................................................111
COMMAND NAME ....................................................112
Default............................................................113
Parameters......................................................113
Remarks..........................................................114
TNC MESSAGES....................................................................................196
Packet Messages.........................................................................196
Mailbox Messages......................................................................197
Command Mode Error Messages .............................................................199
Link Status Messages.................................................................201
HARDWARE ..........................................................................................204
MFJ-TNC Specifications.............................................204
General Description ...................................................................206
Detailed Circuit Description.......................................................206
Oscillator......................................................................206
Dividers and Baud-rate Generator.................................207
CPU Complex...............................................................207
Serial Interface .............................................................208
Watch-dog Timer .........................................................208
Modem.........................................................................209
Power Supply................................................................209
RS-232C Handshaking Protocol .................................................210
Jumper Functions.......................................................................211
HF Tuning Indicator...................................................................217
TROUBLESHOOTING............................................................................218
General Tests .............................................................................218
Step 1: Power Supply...................................................218
Step 2: Obvious Problems............................................219
Step 3: Assembly Problems..........................................219
Step 4: Cabling Problems.............................................219
Specific Symptoms.....................................................................220
Symptom: TNC appears dead.....................................................220
Oscillator and Reset Circuits ......................................................220
Digital Logic Lines.....................................................................220
Symptom: Modem won't calibrate or key transmitter..................221
Symptom: Uncopyable transmitted or received packets...............222
Terminal Interface Troubleshooting.........................................................222
vi
MFJ-1270C/1274C MANUAL TABLE OF CONTENTS
Symptom: MFJ-TNC won't sign on to the terminal.....................222
Symptom: The MFJ-TNC appears to be signing on but only
gibberish is printed on the terminal............................................223
Symptom: The MFJ-TNC signs on OK but won't accept
commands..................................................................................223
Symptom: The MFJ-TNC appears to have "locked-up" i.e. not
responding to any commands. ....................................................224
PACKET RADIO PROTOCOL ...............................................................225
Explanation of Protocol..............................................................225
Physical Layer ..............................................................225
Data Link Layer............................................................226
HDLC Frames ..............................................................226
AX.25 Level Two.......................................................................227
Channel Use and Timing Functions.........................................................230
Channel Flow Control..............................................................................232
RADIO HOOKUP....................................................................................233
MODEM CALIBRATION.......................................................................234
Modulator and Demodulator Frequency Calibration ...................234
Method I.......................................................................234
HF Modem......................................................234
VHF Modem...................................................235
METHOD II.................................................................235
Set Modulator Tones Using Built-in Calibration
Software .......................................................................236
Demodulator Center Frequency Alignment...................237
Tuning Indicator Alignment.........................................238
MFJ-TNC Adjustment Location Map .......................................239
AUDIO OUTPUT CALIBRATION............................................241
Audio Output Level Adjustment Procedure.................................241
HF RADIO ALIGNMENT.......................................................................243
First method: NOISE AVERAGE FREQUENCY.......................243
Second method: FILTER SKIRT AVERAGE FREQUENCY .....243
MFJ-TNC 2400 PACKET OPERATION ...............................................245
2400 Packet Operation Setup......................................................245
B. Receive Audio Setting.............................................245
C. Transmit Audio Setting ...........................................246
JUMPER FUNCTIONS AND LOCATIONS............................................247
COMMAND SUMMARY........................................................................250
vii
MFJ-1270C/1274C MANUAL TABLE OF CONTENTS
viii
MFJ-1270C/1274C MANUAL INTRODUCTION
INTRODUCTION
Thank you for purchasing the MFJ TNC Packet Data controller.
The MFJ TNC interfaces your radio with any personal computer that has an
RS-232 or TTL level Serial Port and a terminal program. While most
communications programs will work, MFJ recommends the use of MFJ Starter
Pack for those who have IBM or compatible, Macintosh, Amiga or Commodore
C64/128 computers. With an IBM or compatible computer, the MFJ Multicom
terminal program gives you added feature like VGA packet picture transfer
(IBM & compatible version) that a standard terminal program just can not
offer.
This compact versatile controller employs the genuine TAPR TNC 2 AX.25
protocol packet firmware. Special firmware like ROSE, NETROM, TheNet are
compatible with the MFJ TNC.
In addition, the advanced new DCD circuit in the MFJ TNC has been
optimized for HF packet. It can be adjusted to ignore background noise while
still being able to respond to a valid data carrier. The new "packet collision
prevention" features -- Prioritized Acknowledgments and Slottime are installed.
This new technology helps prevent many packet collisions inherent in the
current packet protocol.
The MFJ TNC offers the most versatile mailbox available when compared to
the mailbox in other controllers. This mailbox allows dedicated mailbox
callsign so that the mailbox stays on while you operate packet. Other features
like auto forward or reverse forward mail to and from other BBS, remote sysop
access, sysop paging, mailbox ctext, chat mode and a "has mail" LED indicator.
The MFJ TNC has an 8K bytes memory mailbox. Mailbox memory is user
expandable to 32K, 128K or 512K by simply replacing the mailbox memory IC.
If you purchased the MFJ-1274C, you also get MFJ's 20- segment, 10 Hz
Precision Tuning Indicator that makes tuning simple for HF Packet.
The EPROM containing the MFJ TNC firmware is 256K bits. It is expandable
to 512K bit or 1 Megabits giving the MFJ TNC a lot of room to grow in.
A speaker jack lets you plug in a speaker and monitor both transmit and receive
audio. Speaker output also provides packet connect signal alarm.
Page 1
MFJ-1270C/1274C MANUAL INTRODUCTION
A 20-pin header provided for the MFJ TNC to operate packet at 2400 or 9600
baud packet by simply pluging in an optional modem board. The MFJ-1270CT
and the MFJ-1274CT already has a 2400 modem installed. If your MFJ TNC
does not have the 2400 modem installed, it can be purchased separately (MFJ-
2400) and installed by you. With the 2400 modem installed, your MFJ TNC
can operate 300, 1200 and 2400 packet. You may also purchased the MFJ9600 modem board that allows the MFJ TNC to operate at 9600 baud packet.
Items supplied with MFJ TNC package
1. One MFJ TNC Packet controller.
2. One AC adapter power supply for 110V AC. 240V AC adapter supplied
for MFJ-1270CX or MFJ-1274CX (export model for country which operate on
220-240V AC).
3. One open end radio port cable with 5-pin DIN male connectors.
4. One 8-pin connector for the TTL port.
5. One TNC system Instruction Manual.
6. One TNC Fast-Start Manual.
MFJ also has accessory items available for the MFJ TNC. A list of these items
follows on the next page.
Page 2
MFJ-1270C/1274C MANUAL INTRODUCTION
Optional items available for the MFJ TNC
Model No Description
MFJ-1289 Advanced Starter pack for IBM & compatibles
MFJ-1282 Starter pack for Commodore C64/128
MFJ-1287 Starter pack for Macintosh
MFJ-1290 Starter pack for Amiga
MFJ-1272B MFJ TNC to Microphone switch box
MFJ-5024 Radio connecting cable for Icom/Yaesu/RS HTs
MFJ-5026 Radio connecting cable for Kenwood HTs
MFJ-5080 Radio connecting cable for Yaesu 8-pin radio
MFJ-5084 Radio connecting cable for ICOM 8-pin radio
MFJ-5086 Radio connecting cable for Kenwood 8-pin radio
MFJ-280 Monitor speaker for transmit/receiver audio
MFJ-40E Packet encryption EPROM
MFJ-43 TNC Real time clock, keeps your TNC on-time
MFJ-45A 32K RAM IC for additional mailbox memory
MFJ-45B 128K RAM IC for additional mailbox memory
MFJ-45C 512K RAM IC for additonal mailbox memory
MFJ-2400 2400 bps internal modem for packet
MFJ-9600 9600 baud internal modem for packet
The above items are available from MFJ dealers or directly from MFJ
Enterprises, Inc.
Page 3
MFJ-1270C/1274C COMPUTER INTERFACING
COMPUTER INTERFACING
You are now ready to attach your MFJ TNC to your station computer or
terminal. Throughout this manual we will use the term "computer" to refer to
the computer or terminal you use to communicate with your MFJ TNC .
The MFJ TNC communicates with your computer through a serial port using
signals corresponding to a standard called RS-232C. Why an RS-232C
interface? Nearly every computer in production today either incorporates an
RS-232C style serial port as a standard feature, or has one available as an
optional accessory, either from the computer manufacturer or from a
manufacturer of computer accessories. In addition to the RS-232C port, the
MFJ TNC has a built- in TTL port to allow interfacing with computers which
need TTL signals such as the Commodore C-64, C-128 or the VIC-20.
Computer program\, see Terminal program
In order to use the MFJ TNC with your computer, the computer must have an
RS-232C serial port, or a TTL serial port and a program to support the serial
or TTL port. The program will typically be called a modem, terminal emulator,
or communications program.
Since there are so many computers on the market today, it is impractical for
this chapter to provide detailed instructions for each computer. Detailed
information is given for some of the popular models available in the United
States. Also provided is general computer interfacing information.
MFJ Terminal Software Starter Packs
MFJ Enterprises, Inc. offers a Starter Pack for some of the most popular
computers. These Starter Packs contain a terminal program and a cable for
connecting the MFJ TNC to your computer. The Starter Packs available are
listed below and also on the following page:
MFJ-1282:Commodore VIC-20, C64, C128 on 5-1/4" diskette.
MFJ-1283: Commodore VIC-20, C64 on tape.
Page 4
MFJ-1270C/1274C COMPUTER INTERFACING
MFJ-1284: IBM PC & compatibles on 5-1/4" diskette.
(Supports 2-level FAX)
MFJ-1284M: IBM PC & compatibles on 3-1/2" diskette.
(Supports 2-level FAX)
MFJ-1287B: Macintosh, on 3-1/2" diskette.
(Supports 2-level FAX)
MFJ-1290: Amiga on 3-1/2" diskette.
(Supports 2-level FAX)
Computer Interfacing with MFJ Starter Packs
If you are using one of the MFJ Starter Packs, you should use the cable
provided to connect the MFJ TNC and your computer. Follow the instruction
manual provided with the Starter Pack to operate the terminal program and to
connect the MFJ TNC to your computer. After connecting the MFJ TNC to
your computer you can then proceed to the "Computer Baud Rate" section in
this chapter to continue installing the MFJ TNC .
Computer Interface without MFJ Starter Pack
If you are not using a MFJ Starter Packs you should follow the instruction in
this chapter for computer interfacing.
Serial Port Signals
The serial port connector on your MFJ TNC is on the rear panel and is marked
"SERIAL." There are several signals available at this connector. You won't
need all of them for standard normal operation. For some special applications,
such as binary file transfers or some Bulletin Board operations, you may want
to use more of them. In that case, see MFJ TNC Serial Port Pin Functions
in this chapter.
The pins on the serial port connector of the MFJ TNC that must be connected
are shown in Table 2-1. Note that the MFJ TNC connects to a computer
exactly as if the MFJ TNC were a standard RS-232C modem. If you have
successfully used your computer with a telephone modem, hook it up to the
Page 5
MFJ-1270C/1274C COMPUTER INTERFACING
MFJ TNC in the same way. Use whatever program you ordinarily use to
communicate with the modem.
The basic serial port signals reauired by the TNC for normal operation are
listed below in Table 2-1.
Pin Signal Name Description
2 Transmit Data
3 Receive Data
7 Signal Ground The common ground for both data lines.
Table 2-1. Serial port signals required by MFJ TNC .
If your computer is listed below in Table 2-2, refer to the specific information
in the following sections to connect your MFJ TNC to your computer.
Manufacturer Model
Apple Macintosh (tm)
Commodore VIC-20 (tm)
IBM PCjr, PC-XT, PC-AT, 386/486
Radio Shack Color Computer (tm)
Amiga 500, 3000
NEC 8201
Serial data from your computer to the MFJ TNC
Serial data from the MFJ TNC to your computer
Apple II,II+,IIe,II-gs(tm)
C-64 (tm)
C-128 (tm)
most PC compatibles
PC Compatiables
Table 2-2. Computers with specific serial interfacing instructions.
Many computers require a serial port adapter card. These cards incorporate the
circuitry necessary to add an RS-232C port to the computer. Some popular
models in this category are the Apple II series, the IBM Personal Computer,
many Radio Shack computers, and the Sanyo MBC-55X series. If you have one
Page 6
MFJ-1270C/1274C COMPUTER INTERFACING
of these computers with an "add-in" serial port, or if you have another
computer we haven't mentioned, you should skip to one of the sections on
"other computers." If your computer has a 25-pin RS-232C serial port, refer to
the section on Other Computers with 25-pin RS-232C Ports. Otherwise refer to
the section Other Computers with Nonstandard Serial Ports.
Some computers have no serial port and no adapter is commercially available.
Such computers are not suitable for use with the MFJ TNC.
Computers with Specific Serial Interfaces
Apple Macintosh
The Macintosh serial port is an RS-422 compatible port, but it will work fine
with the RS-232C serial port on your MFJ TNC .
MFJ Enterprises, Inc. offers an optional Starter Pack for the Macintosh. It can
be purchased from MFJ Enterprises, Inc. or any MFJ dealer. The Starter Pack
includes an interface cable for connecting the MFJ TNC to the Macintosh and
a terminal program. The Starter Pack for Macintosh is MFJ-1287. If you wish
to use your own cable, you will need a cable wired as shown in Fig. 2-1.
Macintosh MFJ TNC Macintosh MFJ TNC
8 pin DB-25P DB-9P DB-25P
1 (HSKO) 4 1 1
2 (HSKI) 5 5 2
3 (TXD-) 2 9 3
4 (GND) 7 3 7
5 (RXD-) 3 7 8
6 (TXD+) N/C 6 4
7 (GPi) 8
8 (RXD+) 7
Shield 1
Macintosh To MFJ TNC Cable Wiring
Fig. 2-1. Serial port wiring for Apple Macintosh.
Page 7
MFJ-1270C/1274C COMPUTER INTERFACING
Note that pin 1 of the DP-9P connector is not connected inside the Macintosh
or the MFJ TNC . If you use a shielded serial cable, which we recommend,
connect both pin 1s to the shield and connect pin 1 of the MFJ TNC serial
connector to digital ground on the MFJ TNC circuit board. A printed circuit
board pad is provided for this purpose near pin 1 of the serial connector.
Commodore C64, C128 and VIC-20
The MFJ TNC has a built-in TTL-level port for interfacing with the
Commodore C64, C128 or the VIC-20 computers. You do not need a RS-232C
converter to interface with the MFJ TNC.
An optional Starter Pack for the C-64, C-128 or the VIC-20 can be purchased
from MFJ Enterprises, Inc. or from any MFJ dealer. The Starter Pack includes
an interface cable from the MFJ TNC TTL port to the user I/O port on the
Commodore computer. A terminal program is also included. To order, specify
MFJ-1282 for software on disk or MFJ-1283 for software on tape.
If you wish to construct your own cable, the information is as follows:
MFJ TNC
J-5 Pin#
1 RXD Receive Data B,C
2 DCD Data Carrier Detected H
3 GND Ground(Frame & Signal) N
4 RTS Ready To Send E
5 TXD Transmit Data M
6 DSR Data Set Ready L
7 CTS Clear To Send K
Fig. 2-2A TTL port wiring for VIC-20, C64 and C128
*C-128 is used in the C-64 mode for these connections.
**Pin E is not needed when using terminal program referred to in this
chapter for the Commodore computers.
The pin connections for the TTL port (J-5) are numbered from left to right as
you look at the back of the MFJ TNC . All of these connections are not
necessarily used by your terminal program. The MFJ TNC needs RXD, TXD
Mnemonic Name C-64/128*,
VIC-20 Pin#
Page 8
MFJ-1270C/1274C COMPUTER INTERFACING
and GND connected. Programs which utilize file transfer and printer routines
will probably use RTS and CTS as well. Consult your software documentation.
IBM PCjr
The PCjr uses standard RS-232C voltage levels for its serial interface; however,
the connector used is non-standard and not readily available from electronic
supply dealers. Pinout information for this connector is given in the IBM PCjr
Technical Reference Manual.
IBM dealers sell the "IBM PCjr Adapter Cable for Serial Devices" for
converting the connector on PCjr to a standard RS-232C terminal connector.
This cable attaches directly between the MFJ TNC and the PCjr. It is only
about 3 inches long, however, so you may want to obtain a male-to- female RS232C extension cable, which should be readily available.
Radio Shack Color Computer
The Color Computer series (except for the Micro Color Computer) uses a 4-pin
DIN-style connector for its serial interface. Wire a cable as shown in Fig. 2-2
to interface your MFJ TNC to a Color Computer. All necessary parts should be
available from Radio Shack dealers.
Color Computer DB-25P
4 2
2 3
3 7
Fig. 2-2
Serial port wiring for Radio Shack
Radio Shack Model 100/102 and NEC 8201
These computers have built-in standard RS-232C serial ports that are
compatible with the MFJ TNC . You will need a standard male-to-male RS232C extension cable to connect the computer to the MFJ TNC .
Page 9
MFJ-1270C/1274C COMPUTER INTERFACING
IBM PC/XT/AT/386/486 and compatibles Computer
If your computer is a IBM or compatible, you should have a serial port with
standard DB-25 or DB-9 pin connector. You may used a standard IBM serial
modem cable with the correct gender on each end of the cable.
MFJ Enterprises, Inc. offers optional Starter Pack (MFJ- 1284) for the IBM or
compatible computers. The Starter Pack is supplied with the computer
connecting cable (DB-25 male to DB-25 female) for connecting your MFJ TNC
For other computers with a 25-pin RS-232C port, you should consult your
computer manual or accessory manual to see which pins it uses to send and
receive data on, as well as which pin is used for signal common. Follow the
computer manufacturer's recommendations for connecting the serial port to a
modem. You may also find the technical information in this section useful.
Your MFJ TNC is configured as Data Communications Equipment (DCE), the
technical term for an RS-232C modem. Most computers are configured as Data
Terminal Equipment (DTE). If this is the case for your computer, you will
probably be able to simply wire pin 2 of the MFJ TNC connector to pin 2 of
your computer's RS-232C port, pin 3 to pin 3 and pin 7 to pin 7. You can
provide these connections with a standard 3- wire male-to-female or male-tomale RS-232C extension cable, depending on whether your computer has a
DB25S or DB25P connector.
If your computer is configured as DCE, you will have to wire pin 2 of your MFJ
TNC to pin 3 of the computer connector, and pin 2 of the computer connector
to pin 3 of your MFJ TNC . Pin 7 of the computer connector will still connect
to pin 7 of your MFJ TNC serial port. Some computers may require that pin 5
of the computer serial port connector be connected to an appropriate signal.
Others may require connections for pin 8 and pin 20. You can use the
computer's output signals on pins 4 and 6 as shown in Fig. 2-3.
MFJ TNC
RS-232c
2 2
3 3
7 7
Computer
Page 10
MFJ-1270C/1274C COMPUTER INTERFACING
4
5
6
8
20
Fig. 2-3. Serial port wiring with jumpers for auxiliary signals.
Page 11
MFJ-1270C/1274C COMPUTER INTERFACING
Other Computers with Non-standard Serial Ports
Computers with non-standard serial ports must meet the following conditions.
First, the signal levels should be RS-232C compatible. The MFJ TNC requires
that the voltage levels sent from the computer be greater than about +3 volts in
one state and less than about +1 volt in the other state.
Second, the polarity of the signals must conform to the RS-232C standard.
This means that the low voltage state must correspond to a logical "1" and the
high voltage state to a logical "0".
Third, the computer must be able to correctly receive a signal which meets the
RS-232C specification. The MFJ TNC supplies signals that meet this
specification.
Make or buy a cable that provides the following connections. The computer
serial port common pin must be tied to the MFJ TNC serial port connector pin
7. The data line that sends data from the computer must be tied to the MFJ
TNC connector pin 2. The pin on which your computer receives data on must
be tied to the MFJ TNC connector pin 3.
If your computer requires any other signals, you must arrange to provide them.
The documentation provided with your computer or its accessory serial port
should clarify any special requirements of your port.
Terminal Software Requirements
Any software package that enables your computer to act as an ASCII terminal
with an ordinary telephone modem should work with your MFJ TNC. If you
have a program that you have used successfully with a telephone modem and
that you are familiar with, use that program to communicate with your MFJ
TNC.
If you are using a terminal program provided by the MFJ Starter Pack, proceed
to the "Computer Baud Rate" section in this chapter. Follow the instruction
provided by the program.
If you are not using a MFJ terminal program, then proceed with the instruction
for your type of computer.
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MFJ-1270C/1274C COMPUTER INTERFACING
Note: Some terminal programs (such as the Apple II+ Super Serial Card)
requires DCD to be asserted before they receive any characters. If this is the
case, place a jumper across pin 1 and 2 of JMP 1. The DCD LED on the front
panel will function normally indicating received packets.
Apple Macintosh
The MFJ Starter Pack for the Macintosh (MFJ-1287) includes a terminal
program and a cable to connect the MFJ TNC to the Macintosh. If you should
want to use a terminal program such as MacTerm set the options according to
Table 2-3.
Compatibility Terminal
1200 baud VT100
7 bits/character ANSI
even parity UNDERLINE
Handshake Xon/Xoff US
modem connection 80 Columns
"telephone" port ON LINE AUTOREPEAT
Table 2-3. MacTerm option settings for operation with MFJ TNC
Apple II, II+, IIe, IIc
For the Apple II family of computers with Apple or third- party serial interface
cards, you may use ASCII Express Pro, Hayes Smartcom IIe and DataCapture
4.0 for the MFJ TNC . There are others which may be compatible with the
MFJ TNC , but have not been tested.
Commodore C64, C128 and VIC-20
The optional Starter Pack for the C-64, C-128 and VIC-20 can be purchased
from MFJ Enterprises, Inc. or from any MFJ dealer. Starter Pack includes an
interface cable from the MFJ TNC TTL port to the user I/O port on the
commodore computer. A terminal program is also included. To order, specify
MFJ-1282 for software on disk or MFJ-1283 for software on tape.
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MFJ-1270C/1274C COMPUTER INTERFACING
If you do not have the MFJ Starter Pack then you may use the BASIC
communications program is given in the Programmer's Reference Guide
published by Commodore. Use the program listing for "true ASCII," as these
computers use a modified ASCII format internally. You will probably want to
run your MFJ TNC at 300 baud on the serial port with these computers.
NOTE: When using the above program, you must first use the
"COMMODORE" key to shift to lower case before using this program. Also
line 200 should read For J=0 to 64:T%(J)=J:NEXT.
When making the connecting cable from TTL port of the MFJ TNC to the I/O
port of the Commodore computer you may use the wiring information given on
page 2-3 in this chapter. However, do not use pin E connection for this
program.
IBM PCjr
The IBM PCjr has a built-in terminal program in the BASIC cartridge. Start
this program by typing TERM. Refer to your PCjr BASIC manual for details
on this program. For best results with PCjr, do not run the MFJ TNC serial
port faster than 1200 baud.
IBM PC and Compatible Computers
The optional Starter Pack, MFJ-1284) for the IBM PC and compatibles
computers can be purchased from MFJ Enterprises, Inc. or from any MFJ
dealer. These Starter Packs include a graphics terminal program, and a
connecting cable for connecting the MFJ TNC to your computer. MFJ-1284
program allows you to receive 2-level FAX display on the screen. It will also
store the pictures on disk for later viewing.
You may also use many commercial, "shareware" and public- domain terminal
programs for the IBM PC and compatibles computers. Special program written
for packet radio and packet bulletin board service can also be used with the
MFJ TNC . Note that these type of programs will not support printing of
graphics to the computer screen.
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MFJ-1270C/1274C COMPUTER INTERFACING
Radio Shack Color Computer
There are several terminal programs available for the Color Computer. You
will probably want to use a commercial program (rather than writing your own)
since the Color Computer has a "software UART" that is difficult to program in
BASIC.
Some of the terminal programs available are COLORCOM 64, AUTOTERM
and RICKEYTERM (for Coco III). Others are WIZ and XTERM for OS-9.
Radio Shack Model 100/102 and NEC 8201
These computers have built-in terminal programs in ROM. Consult your
computer's documentation for instructions in their use.
MFJ TNC Serial Port Pin Functions
This section describes the pins used on the MFJ TNC RS-232C serial port
connector. It is intended for users with special applications requiring hardware
handshaking. This information should not be needed by most users.
Pin # Mnemonic Name
1 FG Frame Ground
2 TXD Transmit Data
3 RXD Receive Data
4 RTS Request To Send
5 CTS Clear To Send
6 DSR Data Set Ready
7 SG Signal Ground
8 DCD Data Carrier Detect
9 + 12V unregulated reference
10 - 12V unregulated reference
Table 2-4. RS-232C Pin Designations
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MFJ-1270C/1274C COMPUTER INTERFACING
Frame Ground is provided for attachment to the chassis of the MFJ TNC and
the chassis of the attached device (computer or terminal). This pin is brought
out to a feedthrough on the MFJ TNC PC board near pin 1 of the serial
connector. It is not electrically connected anywhere else on the MFJ TNC
circuit board.
Transmit Data is an input line to the MFJ TNC on which the attached device
sends data.
Receive Data is an output line from the MFJ TNC on which the attached
device receives data.
Request To Send is an input line to the MFJ TNC which the attached device
requesting clearance to transmit.
Clear To Send is an output from the MFJ TNC signaling the attached device
to send or refrain from sending data to the MFJ TNC . This line is used for
hardware flow control.
Data Set Ready is an output from the MFJ TNC telling the attached device
that the MFJ TNC is operational.
Signal Ground is the common, or return, path for all signals between the MFJ
TNC and the attached device.
Data Carrier Detect is an output from the MFJ TNC . As normally
configured, DCD reflects the status of the CON LED: It is true when an AX.25
connection exists between your MFJ TNC and another station; it is false when
no connection exists. This configuration is useful when the MFJ TNC is used
with a telephone style Bulletin Board system, since the AX.25 connection,
analogous to a modem signal on the telephone, indicates the presence of a user.
Shorting pin 1 and 2 of JMP1 on the MFJ TNC board will cause this output to
always be true.
Computer Baud Rate
Turn off the power to your computer and to your TNC. Connect the computer
and TNC with a properly configured serial cable. Set the DIP switch on the
rear panel of the TNC to the desired baud rate as shown in Table 2-4. The
power must be OFF when these switches are set.
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MFJ-1270C/1274C COMPUTER INTERFACING
NOTE: The serial port baud rate used between the TNC and the computer has
no relationship to the baud rate used over the radio. The serial port baud rate
you set on your TNC must match the baud rate used by your computer serial
port.
Turn on your computer and start the terminal program. Follow the directions
for the program you are using to match the computer's baud rate with that
selected on the TNC, and to set other options. Set your computer's port options
to 7 bits even parity and select either 1 or 2 stop bits.
Turn on your TNC. You should see a sign-on message, which should be a
readable text message, printed on your computer screen. This demonstrates the
ability of your computer to accept data from your TNC. If you see nothing,
switch off your TNC for a few seconds, then on again. If you still see nothing,
verify your wiring and restart your terminal program. If you see gibberish on
your screen you should verify that you have set the same baud rate for the TNC
and the computer.
Verifying Serial Port Operation
Now that you have a terminal program and the hook-up cable for connecting
the MFJ TNC to your computer, you are ready to verify that MFJ TNC will
communicate with your computer.
1. Turn on your computer. Load and run the terminal program.
2. Set the parameter of the terminal program as follow:
word length: 8 bits
duplex: full
parity: none
stop bit: 1
baud rate: select on of the following:
300, 1200, 2400, 4800, 9600, 19,200
3. Locate the DIP switch in the back panel of the TNC. Set the Dip switch as
according to Table 2-4 follows:
Table 2-4. DIP switch settings for computer serial port baud rates.
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MFJ-1270C/1274C COMPUTER INTERFACING
Baud Rate Dip Switch
1 2 3 4 5
300*
1200 OFF
2400 OFF OFF
4800 OFF OFF OFF
9600 OFF OFF OFF OFF
19200*
CAUTION: Only one of these switches may be ON at any time.
*The MFJ TNC terminal baud rates of 300 and 19,200 is selected by a jumper
on JMP 18 on the mother board. For 300 baud set the shorting jumper to
position 2-3 and for 19,200 baud set the shorting jumper to position 1-2
(factory default).
4. After properly set the DIP switch on the back of the TNC, turn on your
MFJ TNC . Note that PWR, STA and CON LEDs will be lit.
5. If the MFJ TNC terminal parameters match your terminal program
parameter, the MFJ TNC will sign on and the STA and CON LEDs will
extinguish. If TNC failed to sign-on, verify that the terminal parameters and
the TNC computer baud rate is set correctly.
ON
ON
OFF OFF OFF OFF
ON
OFF OFF OFF OFF
OFF OFF OFF
ON
OFF OFF
ON
OFF
ON
6. Upon signing on, the MFJ TNC will display the following sign-on
message on the computer screen:
*:J
bbRAM:LOAD WITH DEFAULTS
|A
MFJ ENTERPRISES, INC.
MODEL MFJ TNC
AX.25 LEVEL 2 VERSION 2.0
RELEASE XXXXX (date) - 32K RAM
CHECKSUM XXX
cmd:
After sign-on the STA and CON on the MFJ TNC will extinguish.
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MFJ-1270C/1274C COMPUTER INTERFACING
If the sign-on message fails to appear, you should check the connecting cable
between and the computer and the MFJ TNC .
When you have successfully read the sign-on message from the MFJ TNC ,
type:
DISPLAY
followed by a carriage return. You should see a lengthy list of items on your
screen. This verifies the ability of the MFJ TNC to accept and respond to input
from your computer. Your serial interface is now working.
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MFJ-1270C/1274C MANUAL RADIO INTERFACING
RADIO INTERFACING
Computer interfacing, covered in the previous chapter, is only half the
interfacing task. The other half is connecting your MFJ TNC to your radio.
MFJ TNC Radio Port
Interfacing the MFJ TNC to your radio involves connecting the following
signals at the TNC Radio Port as shown in Fig. 3-1.
Pin 1 Microphone audio, from the MFJ TNC to your transmitter.
Pin 2 Ground, audio and PTT common.
Pin 3 Push-to-talk, to allow the MFJ TNC to key your transmitter.
Pin 4 Receive audio, from your receiver to the MFJ TNC .
Pin 5 Squelch input (optional) to allow the MFJ TNC to detect activity on a
shared-mode channel.
Fig.3-1 TNC Radio Port Connector
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MFJ-1270C/1274C MANUAL RADIO INTERFACING
This chapter describes how to connect these signals between your MFJ TNC
and your radio and how to adjust the receive and transmit audio levels
appropriately. The interconnection should be planned so as to minimize pickup
of stray audio and RF noise by the lines. If possible, you should set up your
station with a monitor speaker and be able to operate on voice without
disconnecting the MFJ TNC .
Radio Port Connection
Use Fig. 3-2 to wire a microphone connector (not provided) to the 5 pin DIN
cable provided.
You may obtain the specific microphone connector pin designation for your
radio from the your radio's manual. Appendix A at the end of this Instruction
Manual lists pin assignments for some of the most popular radios. The
accuracy of this information is not guaranteed. You should verify this
information with your radio manual.
Fig. 3-2 Radio Port Cable with Connector
A 5-pin male DIN connector cable are provided with the MFJ TNC for wiring
to the microphone connector for your radio.
CHECK THIS CABLE WITH AN OHM METER TO IDENTIFY EACH
WIRE BEFORE WIRING IT TO THE MIC CONNECTOR THAT FITS
YOUR RADIO.
Handheld Radio Connection
Some HTs key the transmitter by drawing a small amount of current from the
microphone input pin (see Fig. 3-3 below). Radios with this type of special
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