Alinco EJ-41U User Manual
Instruction Manual
EJ-41U Terminal Node Controller Unit
Thank you for purchasing this fine Alinco product. This unit enables data communication when
it is properly installed in designated Alinco transceivers. Please read this manual, print the
contents if necessary, and keep this disk for future reference.
Since this device is capable of being used in commercial applications, some of the pages in this
manual are intentionally left blank to accommodate those uses in other regions.
Although we attempt to explain the features of this unit in a simple and comprehensive manner,
unless you have some knowledge about packet communications and APRS, you may have
difficulty understanding the contents of this manual. We apologize, but Alinco cannot provide
basic information of how packet and/or APRS works in general. Please consult your favorite
Ham radio stores for books on the subject and/or web-sites that support your area of interest
regarding those communication modes. You can explore the exciting world of data
communication by yourself, and we believe that this is a most interesting part of the king of
hobbies, Amateur Radio.
APRS® is a registered trademark of Bob Bruninga, WB4APR
Notice
• This unit should be used with ALINCO transceiver DR-135T/E.
• The memory of all settings of the unit are retained by the built-in lithium battery. If they go back to the
default, the battery might be consumed. In that case consult the dealer.
Accessories
The accessories listed below are included. Check that all of them are found before using.
• EJ-41U • 3.5ø stereo plug (for GPS input terminal) • Velcro for installation
• Instruction Manual • Instruction Manual DISK version
Installation
1) Remove the bottom case of DR-135.
2) Attach Velcro on the VCO case.
3) Unplug W1 of DSUB-9 connector from CN107 and plug it into
CN1 connector of EJ-41U.
4) Plug W2 of EJ-41U to the transceiver connector CN107.
5) Attach Velcro on EJ-41U so that it matches to the other Velcro on the
VCO case. (Be careful that the lithium battery doesn’t mount
on the electric part.)
6) Install the bottom case after putting W1 neatly not to be caught in. (*1)
Functions
(1) CN1 (for PC data input/output): Connect W1 to DSUB-9 connector
on the rear side.(Connect DSUB-9 with the RS-232C serial port of
a personal computer.)
(2) W2 (for transceiver data input/output): Plug into CN107 of transceiver.
(3) VR1: For the modulation level adjustment of 9600bps TX data
(4) VR2: For the modulation level adjustment of 1200bps TX data
(5) CON LED (orange): lights while connecting with the other station
in packet communication.
(6) STA LED (green): lights when the transmitting data is remained.
(7) PTT LED (green): lights while transmitting data.
(8) GPS LED (green): flashes when data reaches from GPS receiver during positioning.
(9) Clock Shift: In case that harmonics of 7.9872MHz clock should interfere the RX circuit of the
transceiver while turning ON the power of EJ-41U, short the clock shift by soldering to shift the
oscillating frequency about 200ppm.
Connecting to a personal computer
Connect DSUB-9 connector on the rear side of the transceiver to the
RS-232C COM terminal of a personal computer with the straight-type
DSUB-9 cable that is commercially available
Connecting to GPS receiver
Install the optional 3.5ø stereo plug to the data output line from GPS
receiver. Insert the modified 3.5ø stereo plug to the DATA terminal
on the front of transceiver.
1. Description
A CPU with 4 KB of built-in RAM is used to run the EJ-41U. This allows a very compact and
affordable data communications board. Some of the features of a conventional external TNC
(such as a mailbox) are not found in the EJ-41U. The communication protocol is compatible to
AX.25 version 2 Level 2. This enables a reliable connection with CRC check and the re-try
function. It is also capable of transmitting without being connected to a node (unproto mode or
beacon mode). This protocol is identical to the one conventionally used in a TNC for Amateur
Radio. The 9600 bps non-synthesized serial mode is used to connect to a host (computer or
terminal). The unit is enhanced with a GPS connection capability. The EJ-41U processes and
converts data from a GPS receiver and re-transmits it as a beacon at predetermined intervals.
This advanced feature allows the easy setup of mobile units for GPS position-reporting systems
such as APRS.
Please refer the Alinco transceivers’ instruction manual for the installation of this unit.
2. Commands
In this manual, unless otherwise specified, any “key” stands for the ones on the PC keyboard.
The screen referred to is the PC monitor screen.
2-1 Command mode and Converse mode
The typical operating modes of this unit are the Command mode and the Converse mode.
It is necessary to use the command mode to set internal parameters in the EJ-41U. When the
unit is in the command mode, the “cmd:” prompt will appear on the screen. If “cmd:” does not
show up, press enter (or carriage return [CR]).
The converse mode enables the EJ-41U to transmit text as data. Use this mode for sending files
and/or text. Press the Ctrl and C keys together to return to the command mode.
2-2 General description of the commands
2-2-1: Direct commands
The commands without specific definitions or parameter settings are Direct Commands. These
are mainly used to change modes. These commands are immediate, such as D for Disconnect.
2-2-2: To set parameters
Type the command parameter name. Enter a space after the parameter name and type the new
value. Press [CR] to enter. The screen will show “XXX was YYY”(XXX stands for the parameter,
YYY for the previous value). If the parameter setting is ON/OFF, use the Y key for ON, N key to
select OFF.
2-2-3: To check current parameter settings
Type the command name only and press [CR] key. The monitor will show “XXX is ZZZ” (ZZZ
stands for current value).
2-3: Error indications
2-3-1 [?EH]
This prompt will be displayed when the command does not exist or an invalid string is entered.
2-3-2 [?BAD][?RANGE][?TOO LONG]
If the entered command does not specify the parameter [?BAD] appears. If the command exceeds
the parameter range [?RANGE] appears. If the length of a column is too long, [?TOO LONG]
appears.
2-3-3 [?TOO MANY][?NOT ENOUGH]
If the parameter value is too long [?TOO MANY] will be displayed.
If the parameter value is too short [?NOT ENOUGH] will be displayed.
2-4 Common commands for Amateur Radio Communication
The following is a chart for the commands commonly used in Amateur Radio communications.
Command Description reference
AUTOLF Adds a line-feed [LF] after [CR] 3-3-6
AWLEN Specifies the data bits, 7 or 8, between the host and TNC 3-3-1
BEACON
BBSMSGS
BTEXT
CALBRA
CHECK
CMSG
The transmission interval of the beacon signal in increments of 10
seconds
A hidden command. Changes the message that identifies the TNC
unit.
The message sent out as a beacon at specified intervals set in
BEACON
Calibrate mode. In this mode, the TNC sends the mark and space at
50% duty. Press Q to exit this mode.
Checks if the destination station is still connected and time in
seconds until disconnected after the last message is received.
A hidden command. Activates the automatic transmission of a
message (in CTEXT parameter) when a station connects to the EJ-
4-5-3
9-3-1
4-5-4
4-1-5
4-4-11
4-4-4
41U
CMSGDISC
CONNECT
CONOK
CONVERSE
A hidden command. Sends message in CTEXT and then
disconnects..
Request a connection (after “VIA” if using digi-peaters) eg: C KW1KW
or C KW1KW VIA K6ANC
Allows acceptance of a connection request from another station (or
not).
Puts TNC in the converse mode.
Simply press K to abbreviate.
4-4-6
4-4-1
4-4-3
6-2-1
6-2-2
CPACTIME Validates PACTIME feature in converse mode. 4-6-4
CR Adds a Carriage Return [CR] to outgoing packets. 4-6-2
CTEXT
A hidden command. Sets the message that will be sent out when a
station connects to you. Be advised, the memory is shared with the
4-4-5
LTXT.
DISCONE Sends the disconnection command. 4-4-2
DISPLAY Displays all the current settings of the TNC. 9-2-1
DWAIT
The interval period (in 10 mS units) the TNC waits to send a packet
after the frequency is clear of traffic.
4-2-4
ECHO Activates echo back of your keystrokes on the computer screen 3-3-3
FIRMRNR
FLOW
In RNR frame reception, TNC waits to transmit until next frame
reception.
When on, when you start keyboard activity, TNC output to the
terminal stops.
4-4-12
3-3-4
FRACK The re-try waiting period in units of 1 second. 4-4-8
GBAUD Sets the data communication rate with the GPS receiver 5-6-1
GPSSEND
Use to output up to 159 characteristics to initialize the GPS. This
data cannot be memorized.
5-6-13
GPSTEXT Sets the date string to be sent into LTEXT from the GPS. 5-6-9
HBAUD
Changes the data rate of communication over the radio (1200 or
9600bps)
4-1-1
HEALLED Tests LED on TNC 7-5-1
KISS TNC will enter the KISS mode from the next boot-up. 6-3-1
LOCATION Sets the transmission time of GPS data in 10 second increments. 5-6-4
LPATH Sets the outgoing path of GPS data. (Including DIGI-peater(s) used). 5-6-3
LTEXT The GPS data buffer. 5-6-6
LTMON
MCOM TNC monitors all I frames. 4-7-2
MCON Monitor (or not monitor) other stations while you are connected. 4-7-3
MONITOR Monitor (or not monitor) packet communications. 4-7-1
MRPT Allows monitoring the DIGI-peat route in a packet header (or not). 4-7-5
MYCALL Sets your callsign in the TNC 4-1-2
NTSGRP Adds group-codes into the GPS data. 5-6-10
NTSMRK Adds MARK# in the GPS data. 5-6-11
NTSMSG Add NTS message into the GPS data. 5-6-12
PACLEN Sets the maximum length of the data part of the packet 4-6-3
PACTIME
PERSIST Sets the CSMA P-persistent probability 4-2-2
PPERSIST Selects P-Persistent CSMA 4-2-1
PORTOUT Sets expanded output port 8-1-1
RESET
RESPTIME Sets the transmission delay time of the confirmed packet. 4-4-7
RESTART Re-starts the TNC. 9-1-1
RETRY Set the number of packet retries before disconnecting. 4-4-9
SENDPAC Sets the characters that command a packet to be sent. 4-6-1
SLOTTIME
TRACE Displays the contents of all received frames. 4-7-6
TRIES
TXDELAY
UNPROTO
XFLOW Software flow / Hardware flow controls 3-3-5
Displays the LTEXT message as if it were received as a beacon signal
in preset intervals.
The interval time until automatic packet transmission after
keyboard input stops, in 100ms units.
Returns TNC to its default parameters. This command also resets
the back-up memories.
Sets the interval of generating random numbers in P-persistent
CSMA.
Sets the number of attempts to re-send a packet that has not been
acknowledged as received.
Designates the time delay between PTT and the start of data
transmission.
Sets the destination of packet and the DIGI-PEAT route while
communicating unconnected.
5-6-7
4-6-4
9-1-2
4-2-3
4-4-10
4-2-6
4-5-2
3. Connecting to the host PC
3-1 Communication conditions
Set the PC parameters as follows
* Bit rate 9600Bps fixed
* data length 8 bit / 7 bit AWLEN command
* Parity None/Even/Odd Parity command
* Stop bit 1 bit fixed
The following parameters must meet the terminal software’s requirements.
* wireless modem to the host: echo back setting Echo command
* wireless modem to the host: put [LF] after [CR] AUTOLF command
3-2 Caution on the communication buffer size
3-2-1 host to EJ-41U
The temporary FIFO buffer, which pools serially received data, can only store 64 bites.
Accordingly, when the software flow control is activated, if the host does not respond, the FIFO
buffer will overflow. To analyze commands, the temporary memory buffer of the packet data has
256 bytes available. They are transferred from the FIFO buffer to the stand-by buffer
spontaneously. This does not mean that 1 line ends with only 64 characters!
3-2-2 EJ-41U to host
The FIFO buffer for the data that is to be transferred to the host, such as the received packet data
or echo back, has 720 bites available. If such data exceeds 720 bites, the received packet will be
discarded. In such cases, it communicates to the destination asking to wait for the transfer of
data. Or the retry can be used to request the data be sent again. AX.25 protocol makes it possible
to receive complete data but it may take time. However, data such as beacons may not be recaptured. Please take note of the following to avoid over-flow:
(1) Do not send XOFF (Ctrl+S) from the host and leave in that state it for a long time.
Process the display pause in the shortest possible time.
(2) Do not key input while FLOW command is on (without hitting the ENTER key).
Hit enter key and start the display immediately. Or set FLOW off to avoid a pause.
If the echo command is on, both echo and received data will be displayed which can cause
confusion. This is avoidable if the host application can be activated with echo command off.
(3) Do not transmit to the host large data such as monitor related output.
Do not send uncommon data for normal communications, such as debug data. It eliminates a
line of overflow monitor output.
3-3 Commands
3-3-1 AWLEN command
Abbrev. AW default 8 parameter 7/8 example AW 8
This is used to set the data length for serial communication with the host.
7 stands for 7 bites, 8 for 8 bites. Restart is required using RESTART command, or restart when
the back-up is made.
3-3-2 Parity command
Abbrev. PAR default 0 Parameter 0 to 3 example PAR 0
This is used to set the parity between the host and serial communication.
[0],[2] No parity
[1] odd parity
[2] even parity
Restart is required using RESTART command, or restart when the back-up is made.
3-3-3 Echo command
Abbrev. E default ON range ON/OFF example ECHO OFF
This is used to set the echo-back of characters input from the host. ON for echo-back, OFF for
none. This is compatible to terminal software’s “local echo” setting. If this is not matched properly,
the characters may be displayed twice or the characters may not be seen at all.
3-3-4 Flow command
Abbrev. F default ON range ON/OFF example F ON
When ON is selected, as you start input with the keyboard, the received packet display will be
paused. When the input is complete, send ([CR] in command mode or when transmitting the
packet in converse mode). It separates the TX and RX messages for easier reading of the
messages on the screen. Note that during the pause, if the serial transmitting buffer to the host
is filled, the received packet will be lost.
3-3-5 XFLOW command
Abbrev. X default ON range ON/OFF example XFLOW OFF
This is used to select software flow control ON/OFF. ON to enable flow control. Use XOFF(Ctrl+S)
to pause the display, XON(Ctrl+Q) to resume. In OFF position, the hardware flow control is ON
always.
3-3-6 AUTOLF command
Abbrev. AU default ON range ON/OFF example AU ON
When on, it puts a line-feed [LF] code after the carriage return [CR]. This is to match the
parameters of the terminal software such as [CR] RX, [CR]/[CR]+[LF]. The incorrect setting may
result in overwriting of the new message onto the displayed message or if excessive line feeds
occur.
4. Communication related commands (as a wireless modem)
The following will explain communication-related commands, pertaining to the following
categories.
l The basic TX/RX commands
l TX related commands
l RX related commands
l The commands used when you are connected
l The commands used when you are not connected
l Control commands in converse mode
l Monitor related commands
4-1 The basic TX/RX commands
Check these commands if the unit does not transmit.
4-1-1 HBAUD command
abbrev HB default 1200 parameter 1200/9600
example HBAUD 9600, HB1200
This is to determine the speed of transmitted data. If 1200 is set, it enables AFSK at 1200bps. At
this position the modulated signal is output from the T1200(29
output from the T9600 (35
th
pin). When 9600 is set, GMSK 9600 bps is enabled. T9600 (35th pin)
th
pin) on the gate-array but no
outputs the modulated signal, but NO output from the T1200(29th pin).
4-2-2 MYCALL command
abbrev,. MY default NOCALL parameter : up to 6 alphanumeric characters and SSID
example MY K6ANC-15
This is to set your callsign. Usually callsigns are less than 6 characters. You may add a SSID
(sub-station ID) to identify up to 16 different callsigns. To add a SSID, chose 0 to 15 preceded by
a “dash” [-]. If a SSID is not added, the callsign is processed as SSID [0]. Note that the EJ-41U
can transmit a signal without a callsign being entered (NO CALL). It is illegal to transmit a signal
without your identification, which is a callsign. PLEASE BE SURE TO SET YOUR CALLSIGN
FIRST. Also, if the same callsign is used by different stations (club-station callsign, home and
mobile set-up etc) you will encounter problems. Please use a SSID to differentiate the stations
and avoid problems.
4-1-3 XMITOK command
Abbrev. XM default ON parameter ON/OFF
Example XMITOK ON
This command enables PTT on/off. It should usually be set ON so that the packet will be
transmitted by the radio. If OFF is selected, the data would not be transmitted from the radio
even though data is output. Note that some difference may be found between conventional TNCs
and the EJ-41U on this setting.
Conventional TNC EJ-41U
* default is OFF. * default is ON.
* This parameter may be set automatically * Does not effect the MYCALL setting.
When MYCALL data is input.
4-1-4 Loop command
Abbrev. LOOP default: OFF parameter: ON/OFF
Example: LOOP ON
This command determines the Loop Back test status. When ON is selected, you may be able to
monitor your transmitted messages on the screen, as it is processed in the gate-array. PTT signal
is always off, so the signal won’t be transmitted. While the parameter is ON, you cannot monitor
a received message, either. Set OFF for normal communication.
4-1-5 CALIBRA command
Abbrev. CAL default: none parameter: none
Example: CAL
By using this command, the TNC enters the calibrate mode and outputs mark and space
characters alternately. This is useful for checking the transmitter or for setting transmit
deviation. Type [Q] key to exit.
In the 1200 bps mode, 1200 and 2200Hz signals are output alternately.
In the 9600 bps mode, the signals are not really alternated High/Low, but can be monitored by
observing the eye-pattern of the modulated signals on an oscilloscope.
4-2 TX related commands
To avoid conflicts with other packets, these commands are used to determine how to start
transmission. They are PPERSIST, PERSIST, SLOTTIME, DWAIT, SOFTDCD and TXDELAY.
Please cross-refer relative commands’ description, as they are closely related each other.
(A)PPERSIST is OFF
[Others transmit] [Others transmit] [Start transmit]
DWAIT DWAIT
(1) (2)
DWAIT: As another station stops transmission, DWAIT starts counting. While it is counting,
another station starts transmitting, it stops counting. When this occurs, you cannot transmit.
(1) DWAIT: If no signal is received during the entire DWAIT period, The TNC starts to transmit.
(B)PPERSIST command is ON
[Others transmit] [Start transmit]
Slot time Slot time
(1) (2) (3) (4) (5)
blank blank hit
It’s like a slot-machine.
(1) As others stop transmitting, it generates a random number between 0 and 255. If this
number is higher than the number set in the parameter, it is considered a “blank” and does
not transmit.
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