Operation
Page 32
ETIC - MR1200 - USER MANUAL - 908709-02
Data transmission
When there is data to be sent the terminal transmits it to the MR1200. On reception of the first data
byte an attempt is made to access the radio channel (see
§ 4.4
).
If transmission is momentarily inhibited, the MR1200 will delay data output for several seconds.
If radio channel access is refused (see
§4.4
) the data sent by the terminal is lost.
Otherwise, having gained access to the radio channel the MR1200 begins to send data.
Reception of data
When not transmitting data, the MR1200 is permanently listening out for radio channel activity. If data
is detected, the modem informs the terminal using the 109-DCD line before passing it on. The terminal
cannot refuse communication with the modem.
Termination of radio communication
When data transfer has been concluded - no data awaiting transmission or being received - the MR1200
returns to its rest state after a pre-configured time delay (
tp_rc
parameter).
Communication may, on the other hand, be interrupted by the modem to avoid exceeding the pre-
configured maximum transmission time (
tp_emi
parameter), if a value has been set.
Use of circuits 107-DSR and 106-CTS
Circuit 107-DSR normally has an ON condition set during the period of radio data transfer, and an OFF
condition set when communication has ended. However, the configuration option exists to set this
circuit permanently ON (
ges_dsr
parameter).
Circuit 106-CTS is ON most of the time, being set OFF only when the data transmission buffer
overflows. The signal may be used to control data flow from the terminal.
4.3.3. Marked automatic mode
"Marked automatic" mode is simply a variant of automatic mode, the only difference being with
transmission control : in this mode, transmission begins on detection of a particular pre-defined
character used to end all files to be transmitted.
The ASCII character code is configurable (
mark
parameter).
4.3.4. Direct
mode
In direct mode, transmission is controlled using the RTS signal.
Rest
The terminal holds OFF circuit 105-RTS (logic 0). Circuits 106-CTS and 109-DCD are both OFF.
Data transmission
When there is data to be sent, the terminal begins by setting ON the 105-RTS line. The modem then
attempts to gain access to the radio channel (see
§ 4.4
).
If transmission is momentarily inhibited, the MR1200 will delay outputting data for several seconds.
Radio channel access may, however, be refused (see
§ 4.4
): in this case, 106-CTS remains OFF, but the
terminal can maintain 105-RTS ON in readiness for another attempt.
Having finally obtained access to the radio channel, the MR1200 sets ON line 106-CTS, authorising
the terminal to send its data.
Summary of Contents for MR1200
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