User Manual

Operation
RFI-9256 Radio Modem User Manual Page 26 of 96
Bad
packets
The number of bad packets received.
Lost
packets
The number of packets that have been lost.
Retries The number of retries this unit has used while transmitting.
Good
headers
The number of good header packets received. Header packets contain synchronisation and
control information.
Bad
headers
The number of bad header packets received.
Lost frame
lock
The number of times this unit has lost lock. A loss of lock occurs on a slave when it can no
longer hear the synchronisation messages from the master.
Low RSSI
The number of times the RSSI level has been at or below the nominal sensitivity of the
radio while receiving.
Data Recv The number of user data bytes received.
Data Sent The number of user data bytes transmitted.
Rx
Overflows
The number of times received data has been discarded due to there be no free frame buffers.
Rx
Overruns
The number of times data has been lost due to internal radio errors.
Tx
Overflows
The number of times an attempt has been made to obtain a frame buffer for transmission,
and there have been no free frame buffers.
Busy
Waits
The number of times the slave radio has had data to transmit, but has been unable to do so
due to communications between the master unit and another slave radio.
Table 9: RF communications statistics
4.3 Protocol Operation
The protocol mode of a serial port determines how the serial port data is interpreted and converted into
packets for transmission over the air. There are four basic protocol modes:
 Point-to-point Protocol : Communications occurs between two radios only.
 Broadcast Protocol : Communications occurs between the master and any number of slaves, and
any slave back to the master. Data is broadcast from the master to all slaves, while the slave only
transmits data directly back to the master.
 Hayes Dial-up Protocol : Communications occurs between a master and any number of slaves one
at a time, where Hayes dialling commands are used to create and destroy connections.
 SCADA Protocols : Communications occurs using SCADA communications protocols such as
Modbus, Honeywell, DNP3, or TDE.