User guide

MS-DMT Guide v1.04

Released 05-30-2014

The mode selections when the DATA PORT is active (not 0) can be overridden by “TRANS” when

checked, which places the tool into SYNC with EOM compatible mode of operation setup for a

binary data streams rather than just ASCII. In addition, “TRANS” also bypasses the internal

message and data windows during DATA PORT operation, thus all use of the modem is with the

external software application only. In that regard, a user of the DMT application that is not using

“TRANS” is compatible with when SYNC_EOM for all ASCII data that is sent, and can view any

non-ASCII data if “HEX Eng. View” is checked. However if the sending station sends any content

that contains a Null (0x00) character while in SYNC_EOM the modem receiver will reset at that

point. Additional information of the “DATA PORT” follows herein.

If all stations are not set to the same mode, depending on the combination of mode selections

between stations and what is being sent only gibberish may be displayed on the receiving

station terminal. Also, depending on the combination of modes in use, the receiver may run on

with characters if the receiver is set for EOM use and the sending station is not, in which case

the manual Reset will need to be used. This will be especially true of hardware modem users

and “DATA PORT in TRANS” as the ASYNC_EOM and SYNC_EOM are coded to expect the EOM

and deal with it properly but are also coded in a way that if there is no EOM sent, the modem

receiver will still reset properly.

The MS110A SYNC mode is used with or without an EOM more commonly than ASYNC is used

without the EOM and thus only SYNC mode is provided for use with and without EOM on

transmit. A station that is using a hardware modem will know their configuration, which they

cannot change on the fly as can be done with software modems, thus a hardware modem based

user may request data sent for them in SYNC vs. ASYNC and either with or without EOM. Many

hardware modems do not support disabling of the EOM, however when they do and if they are

used for ARQ and other applications, the modem will likely be setup for SYNC with EOM

disabled.

The SYNC without EOM mode is the most used MS110A hardware modem configuration when

modems are setup for ARQ, FTP, Digital Voice (usually Secure Voice) and with Crypto devices. At

present this software only directly supports basic FEC operation of standard ASCII character

range (decimal 20..128) messages via the SYNC mode with or without EOM via its internal

terminal. However the DATA PORT can also be setup for ASCII or Binary data streams. A

SYNC_EOM compatible mode is used via the Data Port when “TRANS” is checked, regardless of

the mode selection made elsewhere. TRANS supports the use of external software applications

and binary data streams over the full binary byte range of 0x00 through 0xFF where such

applications can send ASCII, Binary or a mix of ASCII/Binary data as achieved with hardware

modems.