Westermo RM-455U-D - Manual (Page 12)

Chapter One Introduction
Man_455U-D Rev 3.04 Page 13
messages within the configured link check timeout (Configuration Setting \T), it will drop the
radio link, and turn off the LINK LED, and reset the DIO and DCD signals (if configured).
Successful Communications
Source Module Destination Module
 Serial data is received
 Serial LED flashes
 Listen to ensure channel is clear
 If clear, transmit message
 Radio TX LED flashes
----------------->
 Receive
message
 Radio RX LED flashes
 Check system and destination
address
 If OK, check error-check
 Radio RX LED flashes
<-----------------
 If message okay, transmit
back an ACK message.
 Radio TX LED flashes
 Acknowledgment received okay -
communication complete
 Serial data is output
 Serial LED flashes
Unsuccessful Communications
Source Module Destination Module
 Listen to ensure channel is clear
 If clear, transmit message
 TX LED flashes
----------------->
 Receives
message
 RX LED flashes
 Check system and destination
address
 If incorrect, transmit no message
and no serial output.
 No ACK received
 Retry multiple times (Configure With
S-Register S30)
----------------->
 If no ACK message received after
all attempts
 “NO CARRIER” message sent to
host
 DCD signal and DCD LED reset
1.4 Security Encryption
Some applications require that the system be made secure from eavesdropping and hacking.
To provide for these applications, the modem supports AES-128 data encryption.
The modem may be configured to transmit messages with or without encryption, accept
messages without encryption, or to require that received messages are encrypted.