RF Innovations CRESCENDO VHF HALF-DUPLEX User manual

CRESCENDO VHF HALF-DUPLEX
USER MANUAL

Crescendo VHF Half-Duplex
User Manual
DISCLAIMER
© 2012 RF Innovations Pty Ltd. All rights reserved.
RF Innovations reserves the right to make improvements on the product in this manual at any time without
notice.
No part of this manual may be produced, copied, translated, or transmitted in any form or by any means
without the written permission of RF Innovations.
Information provided in this manual is intended to be accurate and reliable. However, RF Innovations
assumes no responsibility for its use or infringements upon the rights of third parties that may result from its
use.
Reference No. MAN00110
Revision 4.2
July 2012
Firmware Revision 1.8

Contents
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Contents
1. Introduction................................................................................................................................................................................... 6
2. Installation ..................................................................................................................................................................................... 7
2.1 General considerations............................................................................................................................................................. 7
2.2 External antennas..................................................................................................................................................................... 7
2.3 Safety and Compliance............................................................................................................................................................. 8
2.3.1 Human Exposure to Emissions......................................................................................................................................... 8
2.3.2 Modifications.................................................................................................................................................................... 8
3. Configuration................................................................................................................................................................................. 9
3.1 Overview................................................................................................................................................................................... 9
3.2 Cruise Control........................................................................................................................................................................ 10
3.2.1 Installation ...................................................................................................................................................................... 10
3.2.2 Connecting to a Local Device......................................................................................................................................... 10
3.2.3 Saving and Loading Configurations ............................................................................................................................... 11
3.3 Terminal Menu Interface........................................................................................................................................................ 11
3.4 Hayes AT Command Interface................................................................................................................................................ 12
3.5 Front Panel Interface ............................................................................................................................................................. 13
3.5.1 RSSI, Tx Power, Temperature Status (Mode 2, 3, 4) ..................................................................................................... 13
3.5.2 Main Serial Port Status (Mode 5) ................................................................................................................................... 14
3.5.3 Radio Status LEDs (Mode 1).......................................................................................................................................... 14
4. Serial Port Operation.................................................................................................................................................................. 16
4.1 Overview................................................................................................................................................................................. 16
4.2 Configuration ......................................................................................................................................................................... 17
4.3 Advanced Features................................................................................................................................................................. 17
4.3.1 Control Lines .................................................................................................................................................................. 17
4.3.2 Packetiser Timers............................................................................................................................................................ 18
4.4 Statistics.................................................................................................................................................................................. 19
5. Radio Operation.......................................................................................................................................................................... 21
5.1 Data-Driven Mode.................................................................................................................................................................. 21
5.2 Packet-Driven Mode............................................................................................................................................................... 21
5.2.1 Data Path......................................................................................................................................................................... 22
5.3 Radio Parameters................................................................................................................................................................... 23
5.3.1 Addressing...................................................................................................................................................................... 23
5.3.2 Transmit Power............................................................................................................................................................... 24
5.3.3 RSSI Trip........................................................................................................................................................................ 24
5.3.4 Channel Selection ........................................................................................................................................................... 24
5.3.5 Retries............................................................................................................................................................................. 24
5.4 Network Architecture.............................................................................................................................................................. 25
5.4.1 Network Topology.......................................................................................................................................................... 25
5.4.2 Network Address ............................................................................................................................................................ 27
5.4.3 Store-and-forward Repeater............................................................................................................................................ 28
5.5 Routing ................................................................................................................................................................................... 28
5.5.1 Network Structure........................................................................................................................................................... 28
5.5.2 Routing Table ................................................................................................................................................................. 29
5.6 Diagnostics............................................................................................................................................................................. 30
5.6.1 Data Quality.................................................................................................................................................................... 30

Contents
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5.6.2 RSSI................................................................................................................................................................................ 30
5.6.3 Monitor RSSI.................................................................................................................................................................. 30
5.6.4 PRBS Generator.............................................................................................................................................................. 30
5.6.5 Statistics.......................................................................................................................................................................... 30
6. Protocol Operation...................................................................................................................................................................... 33
6.1 Overview................................................................................................................................................................................. 33
6.2 Data Driven Protocol............................................................................................................................................................. 33
6.3 Point-to-point Protocol........................................................................................................................................................... 34
6.4 Point-to-multipoint Protocol .................................................................................................................................................. 34
6.4.1 Strict and Relaxed Addressing........................................................................................................................................ 34
6.4.2 Local Mode..................................................................................................................................................................... 35
6.5 Hayes Dial-up Protocol.......................................................................................................................................................... 35
6.5.1 Dialling........................................................................................................................................................................... 35
6.5.2 Answering....................................................................................................................................................................... 36
6.5.3 Escape Sequence............................................................................................................................................................. 36
6.5.4 Hanging Up..................................................................................................................................................................... 36
6.5.5 DTR Modes .................................................................................................................................................................... 37
6.5.6 Traceroute....................................................................................................................................................................... 37
6.6 Modbus RTU Protocol............................................................................................................................................................ 38
6.7 Distributed Network Protocol (DNP)..................................................................................................................................... 38
6.8 Datagram Protocol................................................................................................................................................................. 39
6.9 RF Link Status ........................................................................................................................................................................ 40
6.10 Protocol to Radio Address Mapping .................................................................................................................................... 40
6.11 Multiple Protocol Modes...................................................................................................................................................... 42
7. Applications ................................................................................................................................................................................. 43
7.1 Point-to-point Networks ......................................................................................................................................................... 43
7.1.1 Basic Point-to-point Network ......................................................................................................................................... 43
7.1.2 Multiple Port Point-to-point Network............................................................................................................................. 43
7.1.3 Multiple Destination Point-to-point Network................................................................................................................. 44
7.1.4 Point-to-point Network with Repeater............................................................................................................................ 45
7.2 Point-to-multipoint Networks ................................................................................................................................................. 46
7.2.1 Basic Point-to-multipoint Network................................................................................................................................. 46
7.2.2 Point-to-multipoint Network with Roaming Remote...................................................................................................... 48
7.3 Hayes Dial-up Networks......................................................................................................................................................... 49
7.3.1 Basic Hayes Dial-up Network ........................................................................................................................................ 49
7.3.2 Hayes Dial-up Network with Repeaters.......................................................................................................................... 49
7.4 Modbus RTU Network with Repeater..................................................................................................................................... 51
7.5 DNP Network with Repeater .................................................................................................................................................. 52
7.6 Datagram Networks................................................................................................................................................................ 52
7.6.1 Basic Datagram Network................................................................................................................................................ 52
Appendix A Technical Specifications ............................................................................................................................................ 54
A.1 Type Approvals ...................................................................................................................................................................... 54
A.2 Radio Modem Specifications.................................................................................................................................................. 54
A.2.1 Input Current.................................................................................................................................................................. 55
A.3 Connectors Pin Assignments.................................................................................................................................................. 56
A.3.1 Main Serial Port............................................................................................................................................................. 56
A.3.2 Auxiliary Serial Port ...................................................................................................................................................... 56

Contents
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A.4 Dimensions............................................................................................................................................................................. 57
A.4.1 Mounting Plate Dimensions........................................................................................................................................... 58
Appendix B Management Reference ............................................................................................................................................. 59
B.1 Radio Configuration............................................................................................................................................................... 59
B.2 Link Control Configuration and Diagnostics......................................................................................................................... 59
B.3 Serial Port Configuration and Diagnostics............................................................................................................................ 60
B.4 Protocol Mode Configuration and Diagnostics ..................................................................................................................... 61
B.5 Diagnostics............................................................................................................................................................................. 62
Appendix C Hayes References ....................................................................................................................................................... 63
C.1 General Commands ............................................................................................................................................................... 63
C.2 Connection Management Commands .................................................................................................................................... 64
C.3 I-Registers.............................................................................................................................................................................. 64
C.4 S-Registers ............................................................................................................................................................................. 65
C.5 R-Registers............................................................................................................................................................................. 68
Appendix D Factory Defaults......................................................................................................................................................... 69
Appendix E Product Identification Table ..................................................................................................................................... 71
Appendix F Glossary....................................................................................................................................................................... 72

Introduction
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1. Introduction
Crescendo is a series of data-driven and packet-driven radio modems for high-speed data applications.
This manual is specific to Crescendo VHF Half-Duplex. Some of the relevant features of this model include:
Full VHF band switching (148-174MHz)
5W (+ 37dBm) maximum transmit power
Wideband (25kHz) or narrowband (12.5kHz) channels,
with software selectable frequency raster (6.25kHz,
12.5kHz or 25kHz)
Raw air rate 19.2Kbit/s (25kHz channels) or 9.6Kbit/s
(12.5kHz channels)
Half-duplex data-driven or packet-driven operation with
Automatic Repeat Request (ARQ)
Windows GUI for configuration and diagnostics
(Cruise Control)
Internal configuration menu with diagnostic and statistical
information
LED front panel user interface
Two RS-232 serial ports (main and auxiliary)
Operating voltage 9 to 16VDC
Type Approvals:
AS-4295
ETSI (planned)
FCC (planned)
Industry Canada (planned)

Installation
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2. Installation
2.1 General considerations
There are a number of guidelines to observe when installing a Crescendo.
Antenna selection is vital to a good RF link. Different antennas are required depending on the application.
Please contact your antenna manufacturer or RF Innovations for correct antenna selection.
Antenna placement has a significant impact on RF link performance. In general, higher antenna placement
results in a better communication link. A vantage point should be chosen to clear the propagation ellipsoid.
An unobstructed, line-of-sight link will always perform better than a cluttered or obstructed link. See
sections 2.3 below for safety considerations.
Obstructions, such as walls and poles, will distort the antenna radiation pattern and VSWR, resulting in less
efficient transmission and reception.
Antennas in close proximity are potential sources of mutual interference. A transmitter can cause overload of
a nearby receiver, if due precautions are not taken in antenna location. Moreover, transmitters in close
proximity may cause intermodulation. Slight adjustments in antenna placement may help solving
interference problems.
All items of radio equipment, such as antennas, are sources of RF radiation. They should thus be placed
away from electrical equipment, such as computers, telephones or answering machines.
Serial cable runs between radio modem and attached terminal equipment (eg RTU or PC) should be kept as
small as possible. A maximum cable capacitance of 2,400pF is recommended for transfer rates up to
19.2Kbit/s. If a non-shielded, 30pF / foot cable is used, the maximum length should be limited to 80 feet
(approximately 24m). For higher interface speeds, the length of the serial cable should be shortened.
Long serial cables should also be avoided in areas with frequent lightning activity or static electricity build-
up. Nearby lightning strikes or high levels of static electricity may lead to interface failure.
RF Innovations supply a range of external interface converters for applications requiring long cable runs.
2.2 External antennas
Long antenna feed lines cause RF loss, both in transmission and reception levels, and degrade link
performance. When long cable runs are required use a suitable low-loss cable.
As an example, RG58 (tinned-copper braid) will exhibit a loss of 7.1dB/30m at 148-174MHz, whereas
RG58 CellFoil will exhibit 3dB less (4.2dB/30m).
Antennas should not be located within close reach of people, due to radiation hazard. Exposure guidelines
should be followed at all times.
Use extreme caution when installing antennas and follow all instructions provided. Because external
antennas are subject lightning strikes, RF Innovations recommends protecting all antennas against lighting
strike by using lightning surge arrestors.

Installation
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2.3 Safety and Compliance
2.3.1 Human Exposure to Emissions
To limit human exposure, the following guidelines should be observed:
1. Take reasonable precautions in any installation to maintain a clearance of no less than 1 m (one
metre) from the antenna to any person.
2. Do not apply power to the device unless the clearance described in 1 above has been allowed.
The guidelines above apply when transmitting at maximum power, with an antenna gain of up to 13 dB.
For further information on human RF exposure, contact your local health department. For example, Health
Canada‟s Safety Code 6 provides a comprehensive set of guidelines.
2.3.2 Modifications
Changes or modifications not expressly approved by RF Innovations may void the user‟s authority to operate
the equipment legally, as well as any warranty provided.

Configuration
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3. Configuration
3.1 Overview
The Crescendo provides four user interfaces that allow the radio to be configured and its performance to be
monitored:
1. Cruise Control management interface: All radio configuration and diagnostics parameters can be
accessed using the Windows-based Cruise Control Graphical User Interface (GUI).
2. Terminal menu interface: A menu system is available over either of the Crescendo‟s serial ports.
This menu interface can be accessed through any terminal emulation program, such as RFI InTerm,
which can be downloaded from http://www.rfinnovations.com.au.
3. AT command interface: The AT command interface can be used to configure the Crescendo
through ASCII Hayes attention commands. This can be used to read / adjust the Crescendo
configuration and read performance parameters.
4. Front panel interface: The front panel interface consists of six dual colour (red / green) LEDs and a
push button. This panel can display the radio status, RSSI, configured transmit power, temperature,
and serial port status.

Configuration
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3.2 Cruise Control
The following sections briefly outline how to use Cruise Control with the Crescendo. For more information,
see the Cruise Control Manual. Figure 1 below is a typical screenshot of the Cruise Control Configuration
Tool.
Figure 1: Cruise Control Configuration Tool
3.2.1 Installation
The requirements for using the Cruise Control application are:
Pentium III+ Windows based machine.
At least 1 available serial port.
The Cruise Control application is provided on a CD, and runs with a self-installer.
3.2.2 Connecting to a Local Device
In order to connect to a local device, attach the Crescendo to the PC running Cruise Control via a serial port.
Configure Cruise Control with the appropriate serial port settings (19200 8N1 by default), and ensure that
the Crescendo is configured with Hayes AT command interface
1
on the connected port.
1
For a port to accept AT commands it must first be in local command mode. See section 6.5.3 on page 73
for information on enabling and disabling local command mode.

Configuration
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Use the Device -> Connect to Local Device menu item to connect to the local device. Once all
the settings have been downloaded from the device, the available configuration groups are displayed in a tree
on the left. The items that can be configured in each group are displayed in tables on the right.
The names of editable items are displayed in black. Read only items have their names in grey.
Changes made to the configuration or protocol mode of the serial port which Cruise Control is using do not
take effect immediately. They take effect when the disconnect button in Cruise Control is pressed, or the
radio is reset.
It is possible to remotely connect to a device over the air by using Device -> Connect to Remote
Device and entering the remote address of the device. For best results when using a remote connection:
Do not connect to a remote device through store-and-forward repeaters.
Do not connect to a remote device while a live system is running.
3.2.3 Saving and Loading Configurations
The current configuration of a device can be saved by selecting:
File -> Save As...: This saves the configuration of the connected device to a selected file.
The configuration can later be re-applied to a device by using the File -> Upload option or
viewed using Tools -> View Saved Configuration.
It is recommended that only local devices have their configuration loaded from file. Performing this
operation on a remote device updates only those items that can be edited remotely.
3.3 Terminal Menu Interface
The terminal menu provides access to all configuration parameters in the radio. There are two methods to
access the terminal menu:
Execute the AT? command at the Hayes AT command interface. See section 3.4 on page 12 for
information on executing AT commands. The terminal menu will not be started when it is open on
another port, or a Hayes dial-up connection is established. In either case the BUSY response is
returned.
Select mode 6 on the front panel interface. See section 3.5 on page 13 for information on selecting
front panel modes. This will always result in the menu being opened on the auxiliary port, at 19200
8N1.
Changes made to the configuration or protocol mode of the serial port which the terminal menu is using do
not take effect immediately. They take effect when the radio is reset.
A full terminal menu reference can be found in Appendix B on page 59.

Configuration
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3.4 Hayes AT Command Interface
The Crescendo radio supports Hayes ATtention commands. These are used to query radio configuration and
performance parameters, set radio configuration, and establish communication links between radios over the
air.
For a port to accept AT commands it must be first in local command mode. See section 6.5.3 on page 36 for
information on enabling and disabling local command mode.
The format for the query and configuration AT command is:
ATxxx<[I1, I2, … In]><=value><TERM>
Where:
AT is the attention code. All AT commands must be prefixed with AT. This is case insensitive, so
At, aT, or at can also be used.
xxx is the actual command. The list of valid AT commands is given in 0 on page 62.
<[I1, I2, … In]>is an optional section that allows the specification of an index. Indexes are
used to access one of an array of similar items. For example, the Crescendo radio has two serial
ports which can both have different configurations. The command ATS52[0]=1004 set the point-
to-point destination on the main port, while the command ATS52[1]=1004 will set the point-to-
point destination on the auxiliary port.
<=value> is an optional section that is used to set the value of a configuration parameter. If this
section is omitted, then the value of the configuration parameter will be displayed.
<TERM> is the terminator for the AT command. A terminator can consist of a carriage return
(ASCII value 13D) or a carriage return followed by a line feed (ASCII value 10D).
For each AT command that is issued a response is generated. The list of responses to AT commands is
shown in Table 1.
Response
Code
Response
Number
Description
OK
0
Returned whenever a command is entered that is executed correctly.
CONNECT
1
Returned whenever a connection is established with a remote unit.
RING
2
Returned whenever this unit is dialled by a remote unit.
NO
CARRIER
3
Returned whenever a connection fails to be established, or is dropped while it
is operating.
ERROR
4
Returned whenever a command is invalid or could not be executed.
BUSY
7
Returned whenever an attempt is made to dial a remote unit and that unit
already has a connection established, or an attempt is made to enable the menu
via AT? but the menu system is already enabled on the other serial port.
NO
ANSWER
8
Returned whenever an attempt is made to dial a remote unit, and that unit fails
to answer.
Table 1: AT command response codes

Configuration
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3.5 Front Panel Interface
The front panel interface allows for real-time monitoring of radio parameters without external equipment.
The front panel can also be used to enable the menu on the Crescendo‟s auxiliary port regardless of the
current serial port configuration.
There are six front panel modes. To select a front panel mode, press the front panel button. The current panel
mode is shown by lighting a single red LED. To select another front panel mode, continue to hold the button
until the LED scrolls down to the appropriate mode, then release. The list of modes is shown in Table 2.
LED
Mode
Function
1
Radio Status
Section 3.5.3 on page 14 describes the functionality of the
LEDs when in radio status mode.
2
RSSI
Displays the current RSSI as a bar graph. Table 3 shows
the level for each bar item.
3
Transmit
Power
Displays the configured transmit power as a bar graph.
Table 3 shows the level for each bar item.
4
Temperature
Displays the internal temperature as a bar graph. Table 3
shows the level for each bar item.
5
Serial Port
Shows the main serial port status. The meaning of each
individual LED is shown in Table 4.
6
Configuration
Enables the terminal menu on the auxiliary port at 19200
8N1. The LED display is the same as mode 1.
Table 2: Front panel modes
3.5.1 RSSI, Tx Power, Temperature Status (Mode 2, 3, 4)
When in mode 2, 3, or 4 the front panel is used as a bar graph, with the lowest value indicated by all LEDs
off, and the highest by all LEDs on. The bar grows by lighting LED 6 up to LED 1 green. If the top LED is
red, then it indicates that the current value is half way between the listed value and the previous value. Table
3 shows the levels for the bar graph display.
LED
RSSI
Transmit Power
Temperature
1
-60 dBm
+37 dBm
+62ºC
2
-70 dBm
+36 dBm
+50ºC
3
-80 dBm
+30 dBm
+38ºC
4
-90 dBm
+27 dBm
+26ºC
5
-100 dBm
+20 dBm
+14 ºC
6
-110 dBm
+0 dBm
+2 ºC
All Off
-120 dBm
Not Used
-10 ºC

Configuration
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Table 3: Front panel RSSI, transmit power, and temperature modes
3.5.2 Main Serial Port Status (Mode 5)
LED
Description
(1) DCD
Green when the DCD output is low, red when it is high.
(2) DTR
Green when the DTR input is low, red when it is high.
(3) Tx Serial Data
Flashes green when serial data is transmitted from the
Crescendo on either serial port.
(4) Rx Serial Data
Flashes green when serial data is received by the
Crescendo on either serial port.
Flashes red when a receive error occurs on either serial
port. See section 4.4 on page 19 for serial statistics.
(5) RTS
Green when the RTS input is low, red when it is high.
(6) CTS
Green when the CTS output is low, red when it is high.
Table 4: Mode 5 LED functions
3.5.3 Radio Status LEDs (Mode 1)
LED
Description
(1) Tx RF Data
Flashes green when RF data is transmitted.
Flashes red when an RF user or Tx Sync packet is discarded due to retries
being exhausted.
(2) Rx RF Data
Flashes green when RF data is received.
Flashes red when a received RF packet is discarded.
(3) Tx Serial Data
Flashes green when serial data is transmitted from the Crescendo on either
serial port. Flashes red with Rx RF Data when a RF packet is discarded
due to a Tx Serial buffer overrun.
(4) Rx Serial Data
Flashes green when serial data is received on either serial port.
Flashes red when a receive error occurs on either serial port. See section
4.4 on page 19 for serial statistics.
(5) Online
Solid green if packets addressed to the unit has been received. The
duration the LED stays green is set by the Online Timeout.
Solid green when a connection is established with a remote radio.
Flashes red when a point-to-point link goes from the connected to not
connected state.
(6) Power / Fault
Flashes green when the radio is operating normally.
Flashes red when a fault has occurred. Faults are displayed in Cruise

Configuration
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Control under Main -> Diagnostics -> Faults. Faults that are
detected by the radio are:
Point-to-point destination address equal to source address
Reserve section of a datagram packet not equal to 0x0000.
The last time the radio reset was due to a watchdog reset.
When a fault occurs, it is latched for 15 minutes. If after 15 minutes the
alarm has not re-occurred it is cleared. The fault can be cleared manually
by re-powering the radio.
Table 5: Mode 1 LED functions

Serial Port Operation
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4. Serial Port Operation
4.1 Overview
The Crescendo radio has two DCE RS-232 serial ports with DB9 connectors. The serial port pin outs can be
found in Appendix A.3 on page 56.
The main port supports:
TX, RX, and GND.
RTS and DTR inputs.
CTS and DCD outputs.
While the auxiliary port supports:
TX, RX, and GND.
Both serial ports support over the air data transfer. In general, due to the presence of control lines, the main
port should be used as the main data port. The auxiliary port should be used for performance monitoring and
configuration.
Both main and auxiliary serial ports have internal byte buffers on transmit and receive interfaces. This
configuration is shown in Figure 2.
4096 byte output buffer
TX Line (input from DTE)
RX Line (output to DTE)
Input to RF /
internal processing
Output from RF /
internal processing
4096 byte input buffer
Figure 2: Buffering scheme on the Crescendo
This serial port buffering scheme has a number of ramifications on the Crescendo operation:
No preamble is required to account for radio turn-on time.
If the data cannot be sent, it will be buffered until the transmitter is ready.
If the data terminal equipment (DTE) is not ready for data, the Crescendo can buffer the data until
the DTE is ready.
If the buffer is full, additional data received will be discarded until space has become available.

Serial Port Operation
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4.2 Configuration
Both main and auxiliary serial ports support the following configuration options:
Baud rate: 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600 or 115200.
Data bits: 7 or 8
Parity: None, odd, or even
Stop bits: 1 or 2
4.3 Advanced Features
4.3.1 Control Lines
The main serial port has four control lines:
Ready to Send (RTS)
Clear to Send (CTS)
Data Terminal Ready (DTR)
Data Carrier Detect (DCD)
The main serial port supports hardware flow control using the RTS and CTS control lines. When hardware
flow control is enabled:
The radio will only transmit data to the DTE when the RTS line is high.
The radio will raise the CTS line when its input buffer is less than three quarters full, and drop the
CTS line when its input buffer is at least three quarters full.
NOTE: When hardware flow control is enabled, the CTS line configuration is ignored.
In addition to hardware flow control, the CTS and DCD lines can be configured to behave in one of the
following ways:
Always High: The control line is always held high.
Always Low: The control line is always held low.
Mirrors DTR: The control line mirrors the state of the DTR input.
Mirrors RTS: The control line mirrors the state of the RTS input.
Follows Rx Carrier: The control line goes high when a valid carrier is detected and goes low when
the carrier stops.
Follows Tx Enable: The control line goes high when the transmitter is enabled and goes low when
the transmission is finished. This includes acknowledgements and retries when the radio is
operating in packet driven mode.
Follows Online: The control line goes high if a packet addressed to the unit has been received. The
duration the control line stays high is set by the Online Timeout. The Online Timeout can be
configured between 100 and 65535ms. The control line also stays high while a connection is
established with a remote radio.
DTR is used to control Hayes dial-up connections (see section 6.5.5 on page 37)
Main -> Serial Port -> Settings
Main -> Serial Port

Serial Port Operation
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4.3.2 Packetiser Timers
Many protocols delimit packets of data by silence on the communications line for a set period of time. A
common example of such a protocol is Modbus.
Due to the framed structure over the air when the radio is in packet driven mode, packetiser timers should be
used to support protocols and increase the efficiency of data transmission. Packetiser timers can be set
between 0 and 10000ms.
The RX packetiser timer is used to detect the end of each packet. The Crescendo will only begin transmitting
data once the end of the packet has been detected. The suggested RX packetiser timer values for each serial
baud rate when using the radio in packet driven mode is given in Table 6.
For protocols such as ModBus, DNP3, and TDE, the RX packetiser timer should be set greater than
maximum delay between characters in the same packet. Table 6 can also be used as a guide.
Baud
RX Timer
300
>= 35ms
600
>= 18ms
1200
>= 10ms
2400
>= 6ms
4800
>= 4ms
9600
>= 3ms
19200
>= 2ms
38400
>= 2ms
57600
>= 2ms
115200
>= 2ms
Table 6: Packetisation timers for different baud rates
If the packet size is greater than the RX serial buffer size (4096 bytes), then RX packetiser timers should not
be used as the internal buffers will overflow, and bytes will be lost. Tx packetiser timers should be used
instead, and set to the suggested value given in Table 7.
When using the data driven protocol, it is recommended to use TX packetiser timers and data timeout, rather
than the RX packetiser timers, to maintain a low end-to-end latency.
Set the data timeout to the maximum delay between characters in the same packet. Suggested values
are given in Table 6. See section 6.2 for more information on the data timeout setting.
Set the TX packetiser timer to the maximum delay between RF blocks.
Suggested TX packetiser timer values are given in Table 7.
Main -> Serial Port -> Settings

Serial Port Operation
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Channel Width
TX Timer
12.5 kHz
>= 25ms
25 kHz
>= 13ms
Table 7: TX packetisation timers for different channel widths
Using packetiser timers will increase the latency induced by the radio system, as no part of the packet can be
transmitted until it has been fully received.
4.4 Statistics
Statistics are maintained for each serial port and these can be used to analyse and debug problems.
Name
Number
Description
Rx Total
0
The size of the input buffer.
Rx Used
1
The number of bytes currently stored in the input buffer.
Rx Bytes
2
The total number of bytes that have been received.
Rx Errors
3
The total number of errors that have occurred during data
reception. This is the sum of Rx Overflows, Rx Overruns, Rx
Framing, and Rx Parity errors.
Rx Overflows
4
The total number of overflow errors that have occurred. An
overflow error occurs whenever data is received, but the
internal buffer is already full.
Rx Overruns
5
The total number of overrun errors that have occurred. An
overrun error occurs whenever the internal processor is
overloaded and cannot handle the incoming data.
Rx Framing
6
The total number of framing errors that have occurred.
Framing errors usually occur due to mismatched serial port
baud rates between the DTE and DCE.
Rx Parity
7
The total number of parity errors that have been detected.
Tx Total
8
The size of the output buffer.
Tx Used
9
The number of bytes currently stored in the output buffer.
Tx Bytes
10
The total number of bytes that have been transmitted.
Tx Errors
11
The total number of errors that have occurred while
transmitting. This is equal to the Tx Overflows count.
Tx Overflows
12
The total number of overflows that have occurred. An overflow
occurs when the radio attempts to insert data into the transmit
buffer internally, and the buffer is full.
Table 8: Serial port statistics
Main -> Serial Port -> Settings

Serial Port Operation
Crescendo VHF Half-Duplex User Manual Page 20 of 74
These statistics can be used to isolate a number of potential problems in a Crescendo system.
A large number of Rx framing errors indicates that the radio serial port configuration (baud, data
bits, parity, and stop bits) does not match the serial port configuration of the DTE.
A large number of Rx overflow errors indicate that the DTE is supplying data faster than it can be
transferred over the air.
A large number of Tx overflow errors indicate that data is arriving over the air faster than the DTE
can retrieve it from the radio.