Murata DN-24 series User manual

Revision History
Revision
Date
Author
Change Description
1
05/03/2012
F. Perkins
Initial issue
2
01/09/2015
R. Willett
Reformatted to comply with new Murata V.I.
RFM products are now
Murata products.
DN-24 Series
2.4 GHz
Serial Modems
User Guide
©2009-2015 by Murata Electronics N.A., Inc.
DN24G/GI Series User Guide Rev. 2.0 01-09-15 Page 1 of 44 www.murata.com

Important Regulatory Information
RFM Product FCC ID: HSW-DNT24
IC 4492A-DNT24
Note: This equipment has been tested and found to comply with the limits for a Class B digital
device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference in a residential installation. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed and used in accordance with the
instructions, may cause harmful interference to radio communications. If this equipment does
cause harmful interference to radio or television reception, which can be determined by turning
the equipment off and on, the user is encouraged to try to correct the interference by one or more
of the following measures:
1) Re-orientate or relocate the receiving antenna,
2) Increase the separation between the equipment and the radiator,
3) Connect the equipment into an outlet on a circuit different from that to which the receiver is connected,
4) Consult the dealer or an experienced radio/TV technician for help.
FCC Antenna Gain Restriction:
The DN-24 series 2.4 GHz serial modems have been designed to operate with any dipole antenna of up
to 12 dBi of gain, any corner reflector antenna of up to 14 dBi gain, any patch antenna of up to 12 dBi
gain. The antenna(s) used for this transmitter must be installed to provide a separation distance of at
least 20 cm from all persons and must not be co-located or operating in conjunction with any other
antenna or transmitter.
IC RSS-210 Detachable Antenna Gain Restriction:
This radio transmitter, IC 4492A-DNT24, has been approved by the Industry Canada to operate with the
antenna types listed below with the maximum permissible gain and the required antenna impedance for
each antenna type indicated. Antenna types not included in this list, having a gain greater than the
maximum gain indicated for that type, are strictly prohibited for use with this device.
Le présent émetteur radio IC 4492A-DNT24 a été approuvé par Industrie Canada pour fonctionner
avec les types d'antenne énumérés ci-dessous et ayant un gain admissible maximal et l'impédance
requise pour chaque type d'antenne. Les types d'antenne non inclus dans cette liste, ou dont le gain est
supérieur au gain maximal indiqué, sont strictement interdits pour l'exploitation de l'émetteur.
Type Model Number Gain Impedance
Omnidirectional OD12-2400 12 dBi 50 ohm
Corner SCR14-2400CT 14 dBi 50 ohm
Patch PA2412 12 dBi 50 ohm
Dipole S181AH-2450S 2 dBi 50 ohm
©2009-2015 by Murata Electronics N.A., Inc.
DN24G/GI Series User Guide Rev. 2.0 01-09-15 Page 2 of 44 www.murata.com

Under Industry Canada regulations, this radio transmitter may only operate using an antenna of a type
and maximum (or lesser) gain approved for the transmitter by Industry Canada. To reduce potential radio
interference to other users, the antenna type and its gain should be so chosen that the equivalent
isotropically radiated power (e.i.r.p.) is not more than that permitted for successful communication.
Conformément à la réglementation d'Industrie Canada, le présent émetteur radio peut fonctionner
avec une antenne d'un type et d'un gain maximal (ou inférieur) approuvé pour l'émetteur par Industrie
Canada. Dans le but de réduire les risques de brouillage radioélectrique à l'intention des autres
utilisateurs, il faut choisir le type d'antenne et son gain de sorte que la puissance isotrope rayonnée
équivalente (p.i.r.e.) ne dépasse pas l'intensité nécessaire à l'établissement d'une communication
satisfaisante.
This device complies with Industry Canada license-exempt RSS standard(s). Operation is subject to the
following two conditions: (1) this device may not cause interference, and (2) this device must accept any
interference, including interference that may cause undesired operation of the device.
Le présent appareil est conforme aux CNR d'Industrie Canada applicables aux appareils radio exempts
de licence. L'exploitation est autorisée aux deux conditions suivantes : (1) l'appareil ne doit pas produire
de brouillage, et (2) l'utilisateur de l'appareil doit accepter tout brouillage radioélectrique subi, même si le
brouillage est susceptible d'en compromettre le fonctionnement.
Changes or modifications to a DN-24 series serial modem not expressly approved by Murata Electronics
N.A., Inc. may void the user’s authority to operate the module.
©2009-2015 by Murata Electronics N.A., Inc.
DN24G/GI Series User Guide Rev. 2.0 01-09-15 Page 3 of 44 www.murata.com

Table of Contents
1.0 DN-24 Series 2.4 GHz Serial Modems ...............................................................................................5
2.0 DN-24 Systems ...................................................................................................................................5
2.1 Point-to-Point Systems.....................................................................................................................5
2.2 Point-to-Multipoint Systems .............................................................................................................6
2.3 Store-and-Forward Systems............................................................................................................7
2.4 DN-24 Product Descriptions................................................................................................................ 8
3.0 Specifications ......................................................................................................................................9
3.1 Absolute Maximum Ratings.................................................................................................................9
3.2 System Specifications .........................................................................................................................9
3.3 LED Indicators.....................................................................................................................................9
4.0 Installation .........................................................................................................................................10
4.1 Mounting and Location......................................................................................................................10
4.2 Attaching the Antenna.......................................................................................................................11
4.3 DN-24G Connector Details................................................................................................................11
4.4 DN-24GI Connector Details...............................................................................................................12
4.5 Basic DN-24 Point-to-Point System Setup........................................................................................12
5.0 DN-24 Technical Reference..............................................................................................................13
5.1 RF Channel Access...........................................................................................................................13
5.2 DN-24 Addressing.............................................................................................................................13
5.3 Network Linking and Slot Registration..............................................................................................14
5.4 Transparent and Protocol-formatted Serial Data ..............................................................................14
6.0 DN-24 System Configuration.............................................................................................................15
6.1 Configuration Parameters..............................................................................................................15
6.2 Configuring a Basic Point-to-Point System....................................................................................15
6.3 Configuring a Basic Point-to-Multipoint System.............................................................................15
6.4 Configuring a Customized Point-to-Point or Point-to-Multipoint System.......................................16
6.5 Configuring a Store-and-Forward System .....................................................................................18
6.6 Slot Buffer Sizes, Number of Slots, Messages per Hop and Hop Duration...................................18
6.7 Configuring the Serial Port.............................................................................................................21
7.0 DN-24 Protocol-formatted Messages................................................................................................21
7.1 Protocol Formats............................................................................................................................21
7.2 Message Types..............................................................................................................................21
7.3 Message Format Details................................................................................................................22
7.4 Configuration Parameter Registers................................................................................................28
7.4.1 Bank 0x00 - Transceiver Setup ..................................................................................................28
7.4.2 Bank 0x01 - System Settings......................................................................................................30
7.4.3 Bank 0x02 - Status Parameters..................................................................................................32
7.4.4 Bank 0x03 - Serial Settings ........................................................................................................33
7.4.5 Bank 0x04 - Host Protocol Settings............................................................................................34
7.4.6 Bank 0x0FF - Special Functions.................................................................................................35
7.5 Protocol-formatted Message Example........................................................................................35
8.0 Utility Program...................................................................................................................................36
8.1 Serial Communication and Radio Configuration............................................................................38
9.0 Warranty............................................................................................................................................44
©2009-2015 by Murata Electronics N.A., Inc.
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1.0 DN-24 Series 2.4 GHz Serial Modems
The DN-24 series 2.4 GHz serial modems provide a low cost, ready-to-use solution for robust wireless
data communications in the 2.4 GHz ISM band. There are currently two products in the DN-24 series, the
DN-24G and the DN-24GI. The DN-24G provides an RS-232C serial interface with optional hardware flow
control. The DN-24GI offers a selectable 3-wire RS-232C interface or a two-wire, multi-drop RS-485
interface. All DN-24 series modems are based on Murata’s DNT24 frequency hopping spread spectrum
(FHSS) transceiver, and can communicate with other DNT24-based modems and sensor nodes, as well
as customer developed products. DN-24 series modems are supplied with a dipole antenna and a wall-
plug power supply. A DN-24 transmits data at 250 kbps. The RF output power can be set up to 100 mW
EIRP using the supplied 2 dBi dipole antenna. Optional high-gain directional and omni-directional
antennas are available to extend operating range where local regulations allow it. DN-24 series modems
are well suited for sensor and data networks carrying moderate traffic that need robust communications in
locations with non-ideal RF propagation and/or where RF interference or noise are present.
Key Features of the DN-24 Series 2.4 GHz Serial Modems include:
-2.4 GHz wireless connectivity for RS-232C or RS-485 serial interfaces
-Optional 128-Bit AES Encryption
-Point-to-point, Point-to-multipoint, Peer-to-peer and
Store & Forward Capabilities
-Frequency Hopping Spread Spectrum Transceiver
-250 kbps RF Data Rate
-Transmitter Power up to 100 mW EIRP with 2 dBi Antenna
-FCC, Canadian IC Certified and CE Marked for Unlicensed Operation
2.0 DN-24 Systems
DN-24 wireless serial modems can be configured to operate in one of three modes - base, remote or
router. A base controls a DN-24 system, and interfaces to an application host such as a PC. A remote
simply functions to transmit or receive data. A router alternates between functioning as a remote on one
hop and a network base on the next hop. When acting as a remote, the router stores messages it
receives from its parent, and then repeats the messages to its child radios when acting as a network
base. Likewise, a router will store messages received from its child radios when acting as a base, and
repeat them to its parent when acting as a remote. Any message addressed directly to a router is
processed by the router rather than being repeated.
2.1 Point-to-Point Systems
A DN-24 system contains at least one network. The simplest DN-24 topology is a point-to-point system,
as shown in Figure 2.1.1. This system consists of a base and one remote forming a single network. Point-
to-point systems are often used to replace wired serial connections.
©2009-2015 by Murata Electronics N.A., Inc.
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Figure 2.1.1
2.2 Point-to-Multipoint Systems
Figure 2.2.1 shows the topology of a point-to-multipoint (star) system, which consists of a base and more
than one remote in a single network. Point-to-multipoint systems are typically used for data, sensor and
alarm systems. While most traffic in a point-to-multipoint system is between the base and the remotes,
DN-24 technology also allows for peer-to-peer communication from one remote to another.
Figure 2.2.1
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2.3 Store-and-Forward Systems
Figure 2.3.1 shows the topology of a store-and-forward system, which consists of a base, one or more
routers, one or more remotes, and two or more networks. Networks in a store-and-forward system form
around the base and each router. The base and the routers are referred to as the parents of the networks
they form. The rest of the radios in each network are referred to as child radios. Note that a router is a
child of the base or another router while being the parent of its own network. Each network parent
transmits beacons to allow child radios to synchronize with its hopping pattern and join its network.
Different frequency hopping patterns are used by the parent radios in a system, minimizing interference
between networks.
Store-and-forward systems are used to cover larger areas than is possible with point-to-point or point-to-
multipoint systems. The trade-off in store-and-forward systems is longer delivery times due to receiving
and retransmitting a message several times. Store-and-forward systems are especially useful in
applications such as agriculture where data is only collected periodically.
Figure 2.3.1
©2009-2015 by Murata Electronics N.A., Inc.
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2.4 DN-24 Product Descriptions
There are currently two products in the DN-24 series, the DN-24G and the DN-24GI. The DN-24G
provides an RS-232C serial interface. The DN-24GI offers a selectable RS-232C interface or a two-wire,
multi-drop RS-485 interface. DN-24 series modems are based on Murata’s DNT24 frequency hopping
spread spectrum (FHSS) transceiver, and can communicate with other DNT24-based modems and
sensor nodes, as well as customer developed products.
DN-24 series modems are supplied with a reverse SMA dipole antenna and a universal wall-plug power
supply. DN-24 modems transmit data at 250 kbps. The transmitter output power can be set up to 100 mW
EIRP using the supplied 2 dBi dipole antenna. Optional high-gain directional and omni-directional
antennas are available from Murata to extend operating range where allowed by local regulations.
DN-24 series modems are well-suited for sensor and data networks carrying moderate traffic that need
robust communications in locations with non-ideal RF propagation and/or where RF interference or noise
are present.
As shown in Figures 2.4.1 and 2.4.2, serial data to/from a DN-24G is routed through an RS232C signal
converter. In the case of a DN-24GI, serial data is routed through an RS-232C/RS-485 signal converter.
When terminal 3 is left unconnected on the DN-24GI, serial communication is 3-wire RS-232C. When
terminal 3 is connected to terminal 2 or 4, serial communication is 2-wire, multi-drop capable RS-485.
Terminal 3 has no function in a DN-24G. The switching regulator used in all DN-24 modems supports a
wide voltage range on the DC power input, from 9 to 24 Vdc.
Figure 2.4.1 Figure 2.4.2
©2009-2015 by Murata Electronics N.A., Inc.
DN24G/GI Series User Guide Rev. 2.0 01-09-15 Page 8 of 44 www.murata.com

3.0 Specifications
3.1 Absolute Maximum Ratings
Rating Value Units
Power Supply Input Voltage Range -0.5 to +24 V
Non-Operating Ambient Temperature Range -40 to +85
o
C
3.2 System Specifications
Characteristic
Sym
Notes
Minimum
Typical
Maximum
Units
Operating Frequency Range
2406
2475
MHz
Hop Dwell Time
8
100
ms
Number of RF Channels
15 or 24
Modulation FSK
RF Data Transmission Rate 250 kbps
Receiver Sensitivity @ 10
-5
BER -100
dBm
EIRP RF Output Power Level, 2 dBi Antenna
100
mW
Optimum Antenna Impedance
50
Ω
RF Connection
RSMA Coaxial Connector
Network Topologies Point-to-Point, Point-to-Multipoint,
Peer-to-Peer and Store & Forward
Access Scheme
Ad Hoc TDMA
DN-24G RS-232C
9-pin connector, hardware flow control optional
DN-24GI RS-232C Configuration
3-wire, no hardware flow control required
DN-24GI RS-485 Configuration
2-wire, multi-drop capable
Serial Port Baud Rates 1.2, 2.4, 4.8, 9.6, 14.4, 19.2, 28.8,
38.4, 57.6, 115.2, 230.4, 250.0 kbps
Power Supply Voltage Range VCC +9 +24
V
Peak Transmit Mode Current 190
mA
Average Receive Mode Current:
Base, Continuous Data Stream
129
mA
Remote, linked, No Data
34
mA
Remote, Continuous Data Stream
44
mA
Nominal Dimensions
3.3 x 3.2 x 1 inches (84.6 x 82.0 x 25.4 mm)
Mounting Left and Right Flanges, Two Pre-drilled Holes
in Each Flange
Operating Temperature Range -40 85
o
C
Operating Relative Humidity Range, Non-condensing 10 90 %
3.3 LED Indicators
Ref Name I/O Description
1 ACTIVITY O Left-most LED on the front of the unit, amber, indicates RF communications activity.
2 LINK O Middle LED on the front of the unit, red. On a base, this LED indicates one or more remotes
are linked to it. On a remote, this LED indicates it is linked to the base.
3
POWER
O
Right-most LED on the front of the unit, green, indicates the unit is powered up.
©2009-2015 by Murata Electronics N.A., Inc.
DN24G/GI Series User Guide Rev. 2.0 01-09-15 Page 9 of 44 www.murata.com

4.0 Installation
4.1 Mounting and Location
The DN-24G and DN-24GI case outline drawings are shown in Figures 4.1.1 and 4.1.2. The supplied
antenna is hinged, allowing it to be set vertically with the case mounted either horizontally or vertically.
The DN-24 case is designed for indoor use. It must be installed in a weather proof enclosure when used
outdoors, such as a NEMA 4X enclosure. The enclosure must be made of plastic or other materials with
low RF attenuation to avoid compromising antenna performance. Metal enclosures are not suitable for
use with internal antennas as they will block antenna radiation and reception.
DN-24 modems should be mounted at least six feet above the floor (ground) to achieve good
communication reliability in a typical office or retail location. To achieve maximum range and reliability,
especially in industrial locations, the DN-24 should be mounted as high as practical. Murata offers a
number of high gain antennas that can be used to further extend the DN-24’s range. The use of these
antennas is not allowed in all geographical regions; contact RFM’s technical service department for
additional details.
Figure 4.1.1
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DN24G/GI Series User Guide Rev. 2.0 01-09-15 Page 10 of 44 www.murata.com

Figure 4.1.2
4.2 Attaching the Antenna
The antenna (or antenna cable) is attached by screwing the antenna onto the antenna connector. The
supplied antennas are hinged, allowing them to be set vertically with the case mounted either horizontally
or vertically as shown in Figure 4.2.1.
Figure 4.2.1
4.3 DN-24G Connector Details
A coaxial power connector is provided on the DN-24G for the DC power input, and a nine-pin male
connector is provided for the RS-232C signal connection. Straight through wiring should be used between
the DN-24G and its host. The DN-24G serial interface can be used with or without hardware flow control.
DN-24G Power Connector Description
Ref Name I/O Description
T
+PWR
I
The center coaxial conductor (tip) is the positive power supply input, +9 to +24 V.
R
GND
-
The outer coaxial conductor (ring) is the DC power ground.
DN-24G Serial Port Connector Description
Pin Name I/O Description
1 DCD O This pin is an output indicating the modem is linked to the radio network.
2 RADIO_TXD O This pin is the modem serial data output.
3 RADIO_RXD I This pin is the modem serial data input
4
DTR
I
This pin is the data terminal ready input from the modem’s host.
5
GND
-
This pin is signal ground
6
-
-
No connection
7
HOST_RTS
I
This pin is the request to send input from the modem’s host
8 HOST_CTS O This pin is the clear to send output from the modem.
9 - - No connection
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4.4 DN-24GI Connector Details
A terminal strip is provided on the DN-24GI for power and data signal connection. For RS-232C
operation, terminal 3 should be left unconnected and straight through wiring should be used between the
DN-24GI and its host. RS-232C operation is 3-wire; no hardware hand-shaking signals are provided. If
the host application requires hardware handshaking, CTS-RTS and DTR-DCD loopbacks should be
installed on the connector that plugs into the host.
DN-24GI DC Power/Serial Port Terminal Block Description
Pin Name I/O Description
1
+PWR
I
This terminal is the positive power supply input, +9 to +24 V.
2
GND
-
This terminal is a power supply and signal ground.
3 485 EN I When this terminal is unconnected, serial operation is RS-232C. When this terminal
is grounded to terminal 2 or 4, serial operation is RS-485.
4
GND
-
This terminal is a power supply and signal ground.
5 TX/A O This terminal transmits serial data to the host, RS-232C TxD or RS-485 A signal.
6 RX/B I This terminal receives serial data from the host, RS-232C RxD or RS-485 B signal.
For RS-485 operation, terminal 3 should be connected to terminal 2 or 4. RS-485 operation is 2-wire, and
is compatible with multi-drop RS-485 installations. The primary application for the DN-24GI is in RS-485
applications. In this case, the RS-232C mode provides a convenient way to configure the modem prior to
installing it in an RS-485 network.
4.5 Basic DN-24 Point-to-Point System Setup
A basic DN-24 point-to-point system is suitable for many serial data applications. The default
configuration of a DN-24 is a remote with the serial port configured for transparent operation at
9.6 kbps, 8N1. To set up a basic point-to-point system:
1. Configure one of the modules as a base by setting the DeviceMode parameter in Bank 0 to 0x01.
2. Set the MemorySave parameter in Bank 0xFF to 0xD2, which will save the DeviceMode
parameter to EEPROM. Then reset the module, which enables base operation.
3. All other parameters may be left at their default values.
Murata provides a setup utility program called DNCONFIG.exe that configures a DN-24 modem as a base
or a remote, and optionally sets the serial port to a baud rate other than the 9.6 kbps default.
DNCONFIG.exe can be simply copied onto a PC (Windows XP or later operating system) and run. Select
Base in the Mode drop-down box and click Configure and Reset. Note that a DN-24GI must be in RS-
232C mode to use this utility. Another utility program, DNTDEMO.exe, allows full control of all
configuration parameters relevant to the operation of a DN-24 based system. Use this program to set up
advanced DN-24 systems, such as a store-and-forward system. DNTDEMO is discussed in Section 8.0 of
this user guide.
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5.0 DN-24 Technical Reference
5.1 DN-24 RF Channel Access
The time a DN-24 network stays on each frequency in its hopping pattern is called the hop duration or
dwell time, which can be configured from 8 to 100 ms. Radio communication during each dwell is
organized as a time division multiple access (TDMA) frame. A DN-24 frame begins with a base-mode
beacon, followed by 1 to 8 time slots used by the network children to transmit to their parent, as shown in
Figure 5.1.1. A base-mode beacon can include up to 8 messages addressed to one or more child radios.
The number of slots is chosen accommodate the number of children that need to send messages each
hop.
Figure 5.1.1
Each beacon includes the status of all slots - either registered (assigned) or open. When a child radio has
information to transmit to its parent, it randomly selects one of the open slots and transmits all or the first
part of its data. If the parent successfully receives the transmission, it includes the child’s MAC address in
the next beacon. This signals the child radio that the slot is temporarily registered to it, allowing the child
to efficiently stream any remaining data to the base hop-by-hop until it is all sent.
If a child radio does not see its address in the next beacon following its transmission, it again randomly
selects an open slot and retransmits its data. During times when there are no open slots, a child radio
keeps its data queued and continues to look for an open slot in each beacon until at least one slot
becomes available. The access method the DN-24 uses is referred to as Ad Hoc TDMA.
5.2 DN-24 Addressing
Each DN-24 has a unique MAC address. The MAC address can be read or bar-code scanned from the
label on the side of each radio. A DN-24 radio in any mode (base/router/remote) can be addressed using
its MAC address. A DN-24 base can be addressed using either its MAC address or address 0x000000. A
DN-24 can send a message to all other DN-24’s in its system by using the broadcast address 0xFFFFFF.
The base and all routers (parents) hold base-mode network IDs, which are transmitted in every beacon.
All routers and remotes hold parent network IDs and optionally alternate parent network IDs to compare
against the base-mode network IDs in the beacons they receive. A child router or remote is allowed to
join a parent if the child’s parent network ID or alternate parent network ID matches the parent’s base-
mode network ID, or with any parent when its parent network ID is set to 0xFF (wildcard).
In a point-to-point or point-to-multipoint system, the default base-mode network ID of 0xFF (wildcard) can
be used. In a store-and-forward system, however, the base-mode network IDs of all routers must be set
to different values between 0x00 to 0x3F. If the base-mode network ID of 0x00 is assigned to a router, the
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base must be assigned an unused base-mode network ID between 0x01 and 0x3F. Leaving all parent
network IDs in a store-and-forward system set to the default value of 0xFF allows networks to
automatically form, and self-repair if a parent router fails. Enabling the alternate parent network ID also
provides self-repairing message routing.
All DN-24 radios hold a system ID that can be used to distinguish systems that physically overlap. In a
DN-24 system, the system ID must be different from those used by overlapping systems to provide
message filtering. Also, using different base-mode network IDs for all networks in overlapping systems
helps reduce hopping pattern collisions.
The store-and-forward path between the base and any other radio in a system can be determined by
reading the radio’s ParentMacAddress parameter. If this address is not the base, then reading the Parent-
MacAddress parameter of its parent, grandparent, etc., in succession reveals the complete path to the
base. Path determination is useful in optimizing and troubleshooting systems during commissioning and
maintenance.
5.3 Network Linking and Slot Registration
When first turned on, a DN-24 router or remote rapidly scans all frequency channels in its operating band
to acquire synchronization and link to a parent based on a system ID match plus a base-mode network ID
to parent network ID/alternate parent network ID match (or by using a wildcard (0xFF) parent network ID).
In addition to the slot status and the MAC addresses of child radios holding slot registrations, each base-
mode beacon includes one of a number of cycled control parameters. The cycled parameters are
collected by child radios, allowing them to register with a parent, and to later follow any control parameter
changes. When a router or remote has collected a full set of cycled parameters, it can issue an optional
initial heartbeat message and then optional periodic heartbeat messages which allows an application to
maintain the status of all routers and remotes in its DN-24 system.
When a router/remote has data to send to its parent, it picks an open slot at random and transmits. It then
looks for its MAC address in the next beacon. If its MAC address is present in the beacon, it is temporarily
registered to the slot and continues to use it until all current data is sent, or its MAC address drops off the
beacon.
5.4 Transparent and Protocol-formatted Serial Data
A DN-24 remote can directly input and output data bytes and data strings on its serial port. This is
referred to as transparent serial port operation. In a point-to-point system or in multi-point systems when
broadcast addressing is used, the base can also be configured for transparent serial port operation.
In all other cases, serial data will be protocol formatted:
- configuration commands and replies
- announcement messages including heartbeats
Protocol-formatted messages are discussed in detail in Section 7 of this manual. Briefly, protocol-
formatted messages include a start-of-messages character, message length and message type
information, the destination address of the message, and the message payload.
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Transparent data is routed using a remote transparent destination address. In a remote, this address
defaults to the base, 0x000000, and in the base this address defaults to broadcast, 0xFFFFFF. These
defaults can be overridden with specific radio addresses. For example, it is possible to set up transparent
peer-to-peer routing between two remotes in a point-to-multipoint or store-and-forward system by loading
specific MAC addresses in each radio’s remote transparent destination address.
6.0 DN-24 System Configuration
DN-24 radios feature an extensive set of configuration options that allows them to be adapted to a wide
range of applications. Configuration defaults have been carefully selected to minimize the configuration
effort for most applications, while providing the ability to individually adjust the configuration of each radio
to achieve highly optimized system operation.
6.1 Configuration Parameters
The configuration of a DN-24 is controlled by a set of parameters (registers). Parameters that address a
particular aspect of operation are grouped into a bank. All parameters can be accessed through a
module’s serial port and over the radio link. Most parameters are read/write. Read-only parameters
include fixed values such a MAC addresses, firmware version numbers and parameters that are
dynamically adjusted during system operation such as link status. Write-only parameters include security
keys and certain action triggers such as reset. Incorrectly configuring certain parameters can disable a
module’s radio link, but the configuration can always be corrected through the serial port. The
organization of the parameter register banks and the details of each parameter are covered in Section 7.4
of this guide. Sections 7.4.1 through 7.4.6 discuss which parameters apply to various aspects of
configuring a DN-24 system, network or application interface.
6.2 Configuring a Basic Point-to-Point System
A basic DN-24 point-to-point system is suitable for many serial data applications. The default
configuration of a DN-24 is a remote with the serial port configured for transparent operation at
9.6 kbps, 8N1. To configure a basic point-to-point system:
4. Configure one of the modules as a base by setting the DeviceMode parameter in Bank 0 to 0x01.
5. Set the MemorySave parameter in Bank 0xFF to 0xD2, which will save the DeviceMode
parameter to EEPROM and reset the module, enabling base operation.
6. All other parameters may be left at their default values.
6.3 Configuring a Basic Point-to-Multipoint Point System
A basic DN-24 point-to-multipoint point systems is suitable for many serial data applications where
multiple remotes are used. The default configuration of a DN-24 is a remote with the serial port
configured for transparent operation at 9.6 kbps, 8N1. To configure a basic point-to-multipoint system:
1. Configure one of the modules as a base by setting the DeviceMode parameter in Bank 0 to 0x01.
2. If the host application driving the base will individually communicate each remote, set the
ProtocolMode parameter in Bank 4 of the base to 0x01. This step is not required if messages
from the base to the remotes will always be broadcast and/or the base does not need to know the
MAC address of the remote sending a message.
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3. Set the MemorySave parameter in Bank 0xFF to 0xD2, which will save the DeviceMode
parameter to EEPROM and reset the module, enabling base operation.
4. All other parameters may be left at their default values.
5. If the host application driving the base will individually communicate with each remote, the MAC
address for each remote can be obtained from announce packets, heartbeat packets, a
ForceDiscover command, or by reading or scanning the MAC address from the label on top of
each remote.
6.4 Configuring a Customized Point-to-Point or Point-to-Multipoint System
The DN-24 includes many configuration parameters that allow extensive customization of a point-to-point
or point-to-multipoint system. Most applications will require only a few of these parameters be changed
from their default values. But for those applications that need them, Murata recommends the following
configuration sequence. Skip the configuration steps where the default parameter value is satisfactory.
1. Configure one of the modules as a base by setting the DeviceMode parameter in Bank 0 to 0x01.
2. Set the optional AES security key in all system radios by loading your selected 16-byte string into
the SecurityKey parameter in Bank 0 (the default is 16 bytes of 0x00).
3. Select the frequency band of operation by setting the FrequencyBand parameter in Bank 1 of the
base radio as desired (the default is Band 0).
4. Set the transmitter power level as needed in all radios by setting the TxPower parameter in
Bank 0. The default is 63 mW (100 mW EIRP with supplied 2 dBi dipole).
5. Configure the system ID in all radios by setting the SystemID parameter in Bank 0 (the default is
OK if there is no chance of overlapping systems).
6. Load the parent network ID in all remotes in the ParentNetworkID parameter in Bank 0 as needed
(wildcard default is OK for point-to-point and point-to-multipoint systems).
7. Set the BaseModeNetID parameter in the base to match the ParentNetworkID parameter in the
remotes if the default BaseModeNetID is not used in the base and the wildcard default
ParentNetworkID is not used in the remotes.
8. For a point-to-multipoint system where DN-24 MAC addressing will be used, set the
ProtocolMode parameter in Bank 4 of the base to 0x01. Set the protocol mode as needed in the
base and remote of a point-to-point system, and as needed in the remotes in a point-to-multipoint
system. Note that if the application data includes addressing information for individual remote
hosts, the DN-24 broadcast mode can be used instead of the DN-24 protocol mode.
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9. If using transparent serial mode in the system:
a. Set the remote transparent destination address in the RmtTransDestAddr parameter,
Bank 0, in each remote if the destination is not the base (the base address is the default
destination).
b. Set the transparent point-to-point mode to select either the RmtTransDestAddr address
(default) or the address of the originator of the last received message as the remote
destination address. The parameter that controls this destination address is the Trans-
PtToPtMode in Bank 4. Set in all remotes as needed.
c. Set the timeout for transmission of transparent data in the remotes as needed. The
parameter that controls the timeout is the TxTimeout in Bank 4 (the default is to send as
soon as possible).
d. Set the minimum message length for transmission of transparent data in the remotes as
needed. The parameter that controls the length is the MinPacketLength in Bank 4 (the
default is one byte).
10. Refer to Section 7.4.1 below which discusses how to coordinate the values of the following four
parameters:
a. Set the maximum number of messages that can be sent in a hop on each system radio.
The parameter that controls this number is MsgsPerHop in Bank 4. The default is 8
messages.
b. Load the required base slot size into the BaseSlotSize parameter, Bank 1, in the base.
The default is 40 bytes.
c. Configure the number of child slots per hop on the base by setting the NumSlots
parameter. The default is 3 slots.
d. Set the required hop duration on the base. The HopDuration parameter in Bank 0
controls hop duration. The default is 20 ms.
11. Configure the slot lease on the base by setting the SlotLease parameter. The default is 4 hops.
12. Set the heartbeat interval as required in each system radio. The parameter that controls
heartbeats is the HeartBeatIntrvl in Bank 0. The default is 20 seconds/heartbeat.
13. Enable end-to-end message ACKs where required by setting the EndToEndAckEnable parameter
in Bank 0 to 1. Enabling this parameter provides a confirmation that a message has reached its
destination in peer-to-peer or store-and-forward routing. The default is disabled.
14. Set the message retry limit on the base with the ArqAttemptLimit parameter in Bank 1. The
default value is 6 retries.
15. Set the link drop threshold on the base by setting the LinkDropThreshold in Bank 1. This
parameter sets the number of sequential hops without receiving a beacon that will trigger a child
to resynchronize and re-link to its parent. The default is 10 hops.
16. Set the point-to-point reply timeout on the base in the P2PReplyTimeout parameter in Bank 1.
The default is 16 hops. See Section 7.4.2 for parameter details.
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17. Configure the registration timeout on the base by setting the RegistryTimeout parameter in
Bank 1. The default timeout is 50 hops. See Section 7.4.2 for a discussion of this parameter.
18. Load an optional “friendly description” in each system radio in the UserTag parameter, Bank 0.
6.5 Configuring a Store-and-Forward System
The following additional parameters must be set to configure a DN-24 store-and-forward system:
1. Configure the DN-24 radios designated to be routers by setting the DeviceMode parameter
in Bank 0 to 0x02.
2. Enable store-and-forward operation on all system radios by setting the Store&ForwardEn
parameter in Bank 0 to 0x01.
3. In each router, load a unique base-mode network ID into the BaseModeNetID parameter in Bank
0, and into the base if a router is set to 0x00.
4. To configure a specific system topology, set the parent network ID parameter, ParentNwkID, and
optionally the alternate parent network ID parameter, AltParentNwkID, in all routers and
remotes. Note that a store-and-forward system topology can be formed either automatically or
manually, based on the settings of the ParentNetworkID and optionally the AltParentNwkID
parameters:
- Setting the ParentNwkID parameter to 0xFF in all routers and remotes allows each
router and remote to automatically link to a parent, causing the system to form
automatically (child routers picking each other as a parent cannot occur). In this case, the
AltParent-NwkID parameter should be set to 0xFF, which disables it.
- Setting the ParentNwkID and optionally the AltParentNwkID parameters to specific
values in each router and remote allows full manual control of the network topology.
The benefit of automatic system formation is self-healing. If a parent router fails, its child nodes can re-
link to any other parent router they can receive. However, automatic topology formation can result in an
unnecessary number of hops between routers or remotes and the base. The benefit of manual system
topology formation is to avoid unnecessary extra hops in the system, and to balance the number of
children supported by each parent router. If a parent router fails and an active alternate parent network ID
has not been assigned, all children downstream from the failure will be off the system until the failed
router is repaired or replaced.
6.6 Slot Buffer Sizes, Number of Slots, Messages per Hop and Hop Duration
The base slot size (BSS) sets the maximum number of payload bytes the base can transmit during a
single hop when the base is sending one message per hop. The maximum BSS is 105 bytes when a DN-
24 system is configured for one slot. Adding additional slots reduces the maximum BSS by three bytes
per slot. The BSS buffer is set nine bytes larger than the BSS, to a maximum of 114 bytes. The base can
potentially send more than one message per beacon, up to the limit set by its MsgsPerHop parameter
value. Each message in the BSS buffer occupies nine header bytes plus the payload.
For example, the base can send three messages per hop when the BSS is 90 bytes, provided the total
payload bytes in the three messages is 72 bytes or less:
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slot size = 90
buffer = 90 + 9 = 99
3 headers = 3*9 = 27
net for payload = 99 - 27 = 72
The BSS must be large enough to accommodate any protocol-formatted message that may be sent over
the wireless link, as each protocol-formatted message must be sent in a single transmission.
The remote slot size (RSS) is the maximum number of payload bytes a child can transmit during a single
hop when it is sending one message per hop. The RSS is the same for all slots. The maximum RSS is
109 bytes. The RSS buffer is set nine bytes larger than the RSS, to a maximum of 118 bytes. A child can
potentially send more than one message in a slot, up to the limit set by its MsgsPerHop parameter value.
Each message in the transmit buffer occupies nine header bytes plus the payload. For example, a child
can send two messages per hop when the RSS is 73 bytes, provided the total payload bytes in the two
messages is 64 bytes or less:
slot size = 73
buffer = 73 + 9 = 82
2 headers = 2*9 = 18
net for payload = 82 - 18 = 64
Note that the RSS is calculated by all DN-24s in a system, rather than being a user configured parameter.
The slot size depends on the current values of the following parameters:
- base slot size
- hop duration
- number of slots in a frame
The system must be configured such that the RSS is big enough to hold the longest protocol message a
remote will send. This is done by setting the appropriate hop duration for the chosen BSS and number of
slots. The required hop duration for a specific number of slots, base slot size and remote slot size is
calculated as follows:
HD hop duration in µs
NS number of slots
BSS base slot size in bytes
RSS remote slot size in bytes
HD = NS*(80*RSS + 2440) + 80*BSS + 3280 (round HD up to an even multiple of 500 µs)
Example:
NS = 4
BSS = 96
RSS = 109
HD = 4*(80*109 + 2440) + 80*96 + 3280
HD = 44640 + 7680 + 3280
HD = 55600 round to 56000 µs = 56 ms
ExcelFormatted Equations (load the Excel analysis ToolPak add-in for the QUOTIENT function):
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A
B
C
D
E
1 Slots BSS RSS Hop Duration in µs Hop Duration in ms, Rounded
2 Up to the next 0.5 ms Step
3 1 20 20 =A3*(80*C3+2440) + 80*B3 + 3280
=0.5*QUOTIENT((D3+499),500)
For transparent serial port operation without using hardware flow control, the BSS and RSS must be large
enough to accommodate all message bytes that can accumulate between transmissions. The required
BSS and RSS for protocol-formatted messages sent over the wireless link are shown in Table 7.3.1. For
example, the BSS and RSS size required for a TxData protocol-formatted message is three bytes less
than the value in the length byte field of the formatted message.
The default BSS is 40 bytes, number of slots is 3 and hop duration is 20 ms. These parameter settings
provide a 25 byte RSS. These default settings are suitable for point-to-point and small to medium point-
to-multipoint systems operating with protocol-formatted and/or transparent messages. To accommodate
all configuration commands, replies, event messages and announce messages, a 20 byte minimum slot
size is required.
The NumSlots and the MsgsPerHop parameters both affect the number of messages that can be sent on
each hop. The distinction between these parameters is as follows:
- The NumSlots parameter controls the maximum number of individual children that can send
messages to a parent on each hop.
- The MsgsPerHop parameter controls the maximum number of messages a parent or child can
send on each hop.
The NumSlots parameter is configurable only for the base. The base then communicates the NumSlots
value to all other radios in its system. The NumSlots parameter can be set to one for a point-to-point
system, as there is only one child radio. The NumSlots parameter can be set to allow up to eight children
to send messages to their parent during a hop. As discussed above, the hop duration must be increased
as the number of slots are increased to achieve a specific RSS. The default NumSlots parameter value of
three is suitable for many applications.
De facto TDMA operation (guaranteed bandwidth) can be implemented for up to 8 remotes by setting the
SlotLease parameter to a value greater than any gaps in data being sent to a remote by its local host.
This will insure that the base keeps each remote’s slot reserved for it even when there is a gap in the
data.
The MsgsPerHop parameter is configurable for each DN-24 in a system. This parameter is usually set to
a high value in the base and the routers, allowing traffic between a parent and multiple children on each
hop. The MsgsPerHop parameter has little effect in remotes except when a remote needs to send
multiple peer-to-peer messages during a hop. To support sending multiple messages on each hop, the
BSS and RSS must be sized accordingly, requiring a longer hop duration. Note that the messages must
be protocol messages and all messages to be sent on a single hop must be in the module before the
module begins to transmit.
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