User's Manual

SATELLINE-4Pro
User Guide v0.93 DRAFT
32
Handshaking is not needed if the system protocol is designed to prevent collisions (data contention)
by the use of polling, or if there is little traffic and also if there is no harm from occasional data
contention situations (several radio modems try to transmit at the same time).
8.2.1 CTS-line
The options for CTS-line are:
1) Clear To Send
CTS is active when the radio modem is ready to accept data for new transmission. CTS will shift
into inactive state during data reception and transmission.
2) TX buffer state
CTS will shift into inactive state only if the radio modem’s TX buffer is in danger of overflowing. This
typically happens when the serial interface data transfer speed is greater than the radio interface
transfer speed and the size of transmitted messages is large.
8.2.2 RTS-line
The options for RTS-line are:
1) Ignored
RTS-line status is ignored.
2) Flow control
The radio modem transmits data to the terminal device only when the RTS-line is active. Non-active
state of the RTS-line will force the radio modem to buffer the received data. This option is used if
the terminal device is too slow to handle data received from the radio modem.
3) Reception control
RTS-line controls the reception process of the radio modem. An active RTS-line enables reception
(as normal). Non-active RTS-line will interrupt reception process immediately, even if the radio
modem is receiving a data packet. This option is used to force the radio modem into WAIT State
for an immediate channel change.
8.3 Timing and delays during data transmission
When using a radio modem for data transmission, certain delays will be formed through the use of
a radio interface and from the radio modem circuitry itself. These delays exist when the radio
modem switches from Standby Mode to Data Transfer Mode and during reception and transmission
of data. For detailed delay values in each case see Appendix B.