and handshaking. Basic pin connection types that can be used are a three, RXD, TXD
and GND or five, RXD, TXD, GND, RTS and CTS signal line. RS232 is used according to
flow control. In addition, the CD signal line can be utilized for your application.
7.1. Auto Mode
This mode is
“
intelligent
”
and removes the need for the user to understand how the
radio system is used. The data to be transmitted is automatically stored while the
transmitter is turned on and transmitted after finishing preparation for transmission. For
this reason, there is nothing to do to as a user except inputting data to the radio. Even
though there is a timing difference between inputted data from the DTE and transmitted
data from the radio, applying flow control for this mode ensures that the transmit buffer
does not overflow. This operating mode supports software, hardware and none flow
control, and pin connections are changed according to the type of flow control used.
The detailed instruction for flow control is the following.
7.1.1. Flow Control
The buffers in the radio modem and its flow control function permit serial
communications even if the speed differs between the computer (DTE) and the modem
DCE or between the radio modems (modem ports). If there is a speed difference
between the serial port and modem port (DTE speed and radio throughput), the buffers
in the radio modem may become full periodically. Therefore communications speed is
controlled so that data transmission and reception is temporarily halted before the data
exceeds the buffer capacity, and that transmission is resumed when the receiving buffers have
room. This is the flow control function. The radio has two kinds of flow control:
•
Software flow control
•
Hardware flow control
