Company Confidential
23
Raveon Technologies Corp.
6
0-16
RSSI Field
ASCII digits
RSSI Information about this reception. Units in negative dBm.
1
Start of Text (SOT)
2 (0x02)
Indicates beginning of data
7
1-500
Data Field
The data bytes sent/received by the user. May be any binary data
bytes except the DLE ETX sequence.
See Binary Encoding
section on how to send 8-bit binary data.
2
End of Text
( DLE ETX )
16 (0x10)
3 (0x03)
ETX end of the data frame
8
0 - 4
ASCII hex Checksum
(Optional)
Variable
0-FFFF
The 16-bit checksum of all the previous bytes, starting with the
SOH through the end of the data bytes, not including DLE/ETX.
Most significant digit first.
1
End of Transmission
(EOT)
4 (0x04)
Indicates end of the frame
8. Using the M8S
– Packet Data Mode
This section describes the operation of the M8S when it is in the
Packet Mode
of
operation. It is the easiest and most reliable mode of operation for a data
modem.
In Packet Mode, all transmissions are sent in bursts or packets, and contain
address, error detection, and error correction information. Date enters the M8S
modem’s serial I/O port, and is stored in a buffer within the modem until it is
ready to be transmitted. Packetized operation has these advantages over non-
packet modems:
Packet Mode Advantages
1.
Error Detection
The modem uses a 16-bit CRC at the end of every packet
of data. The CRC is used to check the data for errors, and if there are any
errors, the data will not be passed onto the user.
2.
Error Correction
Automatic error correction may be used.
M8S
modems
incorporate an optional ARQ method to re-transmit packets with error, to
ensur
e the user’s data is delivered error-free.
3.
Addressing
Packetized operation allows for a more versatile network
architecture, with source, destination, and network addresses. M8S uses a
16-bit address to identify data packets.
4.
No Dribble Data
Even in the presence of noise, the M8S modem will not
output extra data or have random bit errors. Modems without packet
operation generally do not work well with weak noisy signals.
5.
Transparent Operation
Because of the high-reliability and error-free
operation the Packet Mode offers the user, most user applications will
seamlessly work using the M8S in its Packet Mode.
6.
Repeatable and Routable.
M8S packets are structured so that they may be
repeated using a store-and-forward repeater, and/or routed using specialized
hardware.
