User's Manual
Table Of Contents
- IMPORTANT NOTICE
- RESTRICTIONS ON USE
- PRODUCT CONFORMITY
- WARRANTY AND SAFETY INSTRUCTIONS
- TABLE OF CONTENTS
- INTRODUCTION
- 1 TECHNICAL SPECIFICATIONS
- 2 OPERATING VOLTAGE
- 3 SERIAL INTERFACE
- 4 USER INTERFACE
- 5 RF INTERFACE
- 5.1 Transmitter
- 5.2 Receiver
- 5.3 Priority RX/TX
- 5.4 Error correction
- 5.5 Error checking
- 5.6 User data whitening
- 5.7 Pacific Crest and TRIMTALK compatibility
- 6 TRANSPARENT DATA TRANSMISSION
- 7 SETTINGS
- 8 SW-RELATED COMMANDS AND OPTIONS
- 9 ACCESSORIES
- 10 APPENDIX A
- 11 APPENDIX B
SATELLINE-M3-TR1
User Guide, Version 3.0
29
6.2 Handshake lines
When using the RS-232 serial interface, handshake signals can be used to control data transfer.
Handshake signals are used, for example, by the radio modem to inform the terminal that the
radio channel is busy, and that it cannot initiate transmission. The terminal can also control the
radio modem via RTS-line.
Line
Direction
CTS
To terminal
RTS
To modem
CD
To terminal
A common way of using handshaking signals is to monitor the CTS-line and ignore the others.
Usually the terminal is fast enough to handle the data received by the radio modem, so the use
of RTS-line is not necessary.
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).
6.2.1 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.
6.2.2 CD-line
NOTE! The RS-422 factory setting from the modem Port 2 settings shall be set to RS-232 in case
of using the CD line output. The RS422 setting reserves the CD output for RS usage (pin no: 2).
The options for CD-line are:
1) RSSI-threshold
CD is active whenever a signal with a level exceeding the level required for reception exists on
the radio channel. It doesn’t make any difference if the signal is an actual data transmission, a
signal of a radio transmitter not belonging to the system, or even an interference signal caused
for example, by a computer or a peripheral device. CD is also active when the radio modem in
question is transmitting.