Hostmode information on Kantronic TNC
------------------------------------------------------------------ : This file describes the HostMode on the Kantronics TNC. This : : file is issued by LA6GHA, Bob, but unfortunately the author is : : unknown. Many thanks to SM7OYP for his help. : : 73's de LA6GHA : ------------------------------------------------------------------
KANTRONICS HOST MODE OPERATION --------------------------------
In order to operate in the Host mode with Kantronics TNC, you must first set the Intface command to Host. After this accomplished, it will be necessary to perform a soft reset in order to enter the Host mode. This may be accomplished by typing reset at the cmd: prompt. If you want the TNC to always operate in the Hostmode, be sure to give the command PERM. (Unless you have battery-backup).
You will also need to set the abaud command to the appropriate baud rate for your terminal. If the abaud command is not set, the TNC will run its normal autobaud routine, looking for an asterisk (*) from the keyboard. When the asterisk is entered, the TNC will then immediately enter Hostmode. While operating Hostmode, your program must use hardware flow control (RTS/CTS). Software flow control is not possible in Host mode. In the KAM, Host mode only applies to the packet mode (v 3.05 and lower)
COMMUNICATION FORMAT - HOST COMPUTER TO TNC
Communication from the Host to the TNC must occur in blocks. The block of data is delimited with a FEND character ($C0) at the beginning and end. If the FEND character appears within the block as valid data, the Host must replace this character with a special sequence, consisting of a FESC ($DB) by a TFEND ($DC). One other special sequence may be required in the event a FESC ($DB) characters is required in the data field. This is accomplished by the special sequence of a FESC ($DB) followed by a TFESC ($DD). These special sequences are the same used in the kiss code, as implemented by Phil Karn, KA9Q.
After the opening FEND, the next character is the command byte and will indicate the type off command being given to the TNC. The permissible characters in the command byte are C, D or Q. For the KAM only, there are some other combinations used for non-packet HF mode operation. These will be covered later.
A "C" command byte indicates a command that the TNC will interpret as if it were in the command mode. If the command mode byte is a "D", the TNC will consider the data as data to be transmitted on the specified port and stream. The letter "Q" in the command byte will cause the TNC to exit the Host mode and return to terminal mode.
The next byte is the port byte. This byte must be used with every block of type "D" to signify which port (1 or 2) is to be used for transmission of the data. Type "C" blocks must always specify this as either 1 or 2, but this is only used on those commands that are specific to a port. This would include the connect and disconnect commands. When using KAM, the VHF port is selected by a port byte of "1" and the HF port is "2". Single port units use port byte "1".
The fourth byte is the stream byte. This byte determines which stream (A-Z) the TNC will use for the data. If the stream byte is 0 for a data packet (command byte D), the data will be sent out unproto. (See the section on the KAM HF modes for more information). For commands that do not not involve a specific port or stream, the port and stream bytes are ignored, but must be specified. In the cases, you should address port 1 stream A.
After these four header bytes, the structure of the block for a command is exactly the same as if you were entering the command from terminal mode of the TNC. If entering data to be transmitted, simply place the data in the following bytes. Note that commands do not need a carriage return included in the data portion of the packet.
After the data or command, terminate the information from the Host with a FEND ($C0) character.
KAM HF MODES
When operating non-packet modes (i.e., RTTY, ASCII, AMTOR, or CW) with the KAM, a few additional Host to TNC frames are required. First select the mode with the standard command structure as described above (e.g., FEND C2ARTTY 75 FEND). Data that you wish to transmit to the other station should have command byte "D", port byte "2", and stream byte "0"
Special Host frames for these modes are:
FEND T FEND Enter transmit mode FEND E FEND Enter receive mode when buffer empty FEND R FEND Enter receive mode immediately FEND X FEND Return HF port to packet mode FEND CTRL-X FEND Clear the transmit buffer in KAM HF
TNC TO HOST COMPUTER
Communication from the TNC to the Host also occurs in blocks which are delimited at beginning and end with FEND characters ($C0).
After the beginning FEND, the next character is the status byte. A status byte "C" is a response to a command from the Host with the command byte "C". A status byte of "D" indicates that the data was received on a connected stream (see the section below on the KAM HF operation). "M" in the status byte means that the data in this block is the result of the monitor commands. A status byte of "S" is a message caused by a change in the link state. Such messages include the ***DISCONNECTED, and FRMR sent. A special "S" block of data consists of two FEND characters, the characters S00 and another FEND character. This indicates that the TNC has performed a soft reset, and all existing connections (if any) are not longer valid. This is equivalent to the TNC having just been turned on.
A data block with the status byte ***connect request. A block with status byte "T" is the result of the trace command. Port and stream bytes (defined below) are valid for "D" and "S" blocks, but only the port byte is valid for "T", "M",and "R" blocks. The port byte follows the status byte, and will contain the port number the specific information is from. This will be a "1" if the TNC is single port operation, or a "1" or "2" if in dual port operation. When using the KAM, the VHF port is indicated by a port byte of "1". The stream byte follows the port byte. The stream byte will be "A"-"Z" for data on the connected streams.
Data being sent to the Host which is not connected data will have the stream byte set to "0". If the TNC returns a "C" status block with no data, this indicates that the command was accepted. This will occur on connect and disconnect commands. A "T" block from the Host (trace information) is raw data, and not a hex dump of the received packet. The kiss transparency (FESC, FEND, and TFESC) described above is always applied to all blocks.
HF MODE OPERATION
When using a non-packet mode on the HF port of the KAM, received HF data will be sent to the Host with status "D", port byte "2", and stream byte "0". Each received character is sent from the KAM to the Host in a separate block.
When operating AMTOR mode A, another KAM to Host block is possible, indicating the current status of your station (IRS or ISS). The block has status byte of "I", port byte "2", and the stream byte indicates IRS ("0") or ISS ("1"). This block will be sent whenever there is a change. When operating in the AMTOR mode A (ARQ) the KAM will send a "S" block containing information pertinent to the link. For instance, when the link is established, the KAM sends a "S" frame with the message <LINKED> or <LINKED TO xxxxxx>. "S" frames are also sent indicating a link failure, or anytime the KAM returns to amtor standby. This can occur when the other station breaks the link, or if the link fails due to poor propagation.
When receiving NAVTEX, the KAM does not send any information to the Host until it has received a proper NAVTEX header for a message that is vaild to be printed (see the NAVTEX section of the operations manual). The header will be sent to the Host in a single block. After the closing NNNN of the message if the number of errors received exceeds the NAVERR setting, an error message will be sent from the KAM to the Host indicating ***too many errors*** and the message number. This will be sent in a "D20" frame and not as a status frame. This allows this message, to be stored in the file, if you are capturing the HF channel to disk. This message will also be sent if the link fails before the closing of the current message.
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