atim

ATiM

Spécialiste en étude et développement de produits

de radiocommunicationwww.atim.com

ARM-SE

« Advanced Radio Modem Serial & Ethernet »

ATIM: le spécialiste de la radiocommunication 2

o Morning:o Theory - Operating Principles

• Radio Notions• Serial Links Notions• Network Notions

o ARM-SE• Description• Operating Modes• Radio Settings• Extras

o Afternoon:o Workshop


Agenda

Radio NotionsTheory – Operating Principles


o Basic Communication Systemo Transmitter and Receiver

RF Basics


Transmitter Receiver

Basic Radio Communication Systemo Transmitter and Receivero Transmitting Antenna

RF Basics


Transmitter ReceiverAntenna 1

Basic Radio Communication Systemo Transmitter and Receivero Transmitting Antennao Receiving Antenna

RF Basics


Transmitter ReceiverAntenna 1 Antenna 2

Basic Communication Systemo Transmitter and Receivero Transmitting Antennao Receiving Antennao Environment

RF Basics



Environment

Basic Communication SystemRF Basics



Environment


Environment

RF Basics


o Maximizing Range

RF Basics



Maximizing Rangeo Increase Transmitter (TX) Power

• Government Regulated• Low-powered Applications

RF Essentials


Increase Power ReceiverAntenna 1 Antenna 2

Maximizing Rangeo Increase Transmitter (TX) Powero Increase Receiver (RX) Sensitivity

• Specified in dBm (more of this later)

RF Essentials


IncreasePower

ImproveRX Sensitivity

IncreaseGain

IncreaseGain

Maximizing Rangeo Increase Transmitter (TX) Powero Increase Receiver (RX) Sensitivityo Increase Antenna Gain

• More gain equates with more focusing of energy• Antenna cables should be as short as possible

RF Essentials


Transmitting AntennaFocused energy

Receiver AntennaFocused energy

o Maximizing Rangeo Increase Transmitter (TX) Powero Improve Receiver (RX) Sensitivityo Increase Antenna Gaino Clear the Environment of obstructions

• Visual (Linear) line-of-sight vs. RF (Radio) line-of-sight

RF Essentials


IncreasePower

ImproveRX Sensitivity

IncreaseGain

IncreaseGain

Clear theEnvironment

o Fresnel Zoneo Football-shaped path

RF Essentials


FresnelZone

Site A

Site B

d2

d1

Radius of n th Fresnel Zone given by:

21

21

dd

ddnrn+

=l

o Fresnel Zone diameter depends upon Wavelength, and Distances from the sites along axis

o For minimum Diffraction Loss, clearance of at least 0.6F1+ 3m is required

RF Essentials

2nd*

1st*

3rd*

* Fresnel Zones

o Fresnel Zoneo Football-shaped patho Acceptable = 60% of Zone 1 + 3 meterso Raise antennas to help clear the zone

RF Essentials


o Fresnel Zone Diameters

RF Essentials


RangeDistance

868 MHz ModemsRequired Fresnel Zone

Radius1 m 0,29 m

3 m 0,51 m

10 m 0,93 m

30 m 1,61 m

100 m 2,94 m

300 m 5,09 m

1600 m 11,76 m

8000 m 26,29 m

16000 m 37,18 m

o RF starts with AC (Alternating current)

o The antenna converts radio frequency electrical energy fed to it (via the transmission line) to an electromagnetic wave propagated into space.

RF Terminology


o Wavelength is the distance between identical points in the adjacent cycles of a waveform. In wireless systems, this length is usually specified in meters, centimeters, or millimeters

o The size of the wavelength varies depending on the frequency of the signal. Generally speaking, the higher the frequency the smaller the wavelength.

RF Terminology


Wavelength = 3 x 108

f (frequency in Hz) 868MHz -> 34.5 cm

o Frequencyo Measured in Hz (Hertz)o With appropriate multiplier

• kHz – Kilohertz (Thousands of Hertz)• MHz – Megahertz (Millions of Hertz)• GHz – Gigahertz (Billions of Hertz)

o Frequency Classificationo VLF – Very Low Frequency 10-30kHzo LF – Low Frequency 30-300kHzo MF – Medium Frequency 300-3000kHzo HF – High Frequency 3-30MHzo VHF – Very High Frequency 30-300MHzo UHF – Ultra High Frequency 300-3000MHzo SHF – Super High Frequency 3-30GHzo EHF – Extremely High Frequency 30-300GHz

RF Terminology


o Tx is short for “Transmit”o All radios have a certain level or Tx power that the radio generates at the

RF interface. This power is calculated as the amount of energy given across a defined bandwidth and is usually measured in one of two units:

1. dBm – a relative power level referencing 1 milliwatt2. W – a linear power level referencing Watts

dBm = 10 x log[Power in Watts / 0.001W]W = 0.001 x 10[Power in dBm / 10 dBm]

RF Terminology


o Rx is short for “Receive”o All radios also have a certain ‘point of no return’, where if they receive a

signal less than the stated Rx Sensitivity, the radio will not be able to ‘see’ the data.

o This is also stated in dBm or W.

RF Terminology


o In a wireless system, antennas are used to convert electrical waves into electromagnetic waves. The amount of energy the antenna can ‘boost’ the sent and received signal by is referred to as the antennas Gain.

o Antenna gain is measured in:

1. dBi: relative to an isotropic radiator2. dBd: relative to a dipole radiator

0 dBd = 2.15 dBi

RF Terminology


o Omni-Directionalo Shorter Distanceso Greater Coverage

o Directionalo Greater Distanceso Area coverage sacrificed

RF Terminology


o Link Budget CalculationsRF Calculations


– Path Loss (dB)

– Field Factor (dB)

– Antenna Gain– (dBi)

– Cable Losses– (dB)

– Connector– Losses

– (dB)

– Connector– Losses

– (dB)– Cable Losses

– (dB)

– A – B

– Received Signal Level – (dBm) = Tx Output (dBm) - Path– Loss(dB) - Field Factor (dB) + Total Antenna Gains (dB) - Total– Cable Losses (dB) - Total Connector Losses (dB)

– Antenna Gain– (dBi)

– Tx Output (dBm)– Tx Output (dBm)

o ARM-SE Example

RF Calculations


5 mW 7 dBm

25 mW 14 dBm

500 mW 27 dBm

TRANSMISSION POWER

0,5km -81 dBm

1km -91 dBm

2 km -97 dBm

ATTENUATION BY AIR

3 km -101 dBm

4 km -103 dBm

5 km -105 dBm

6 km -107dBm

7 km -108 dBm

9600 Bauds -110 dBm

19200 Bauds -107 dBm


RECEIVER SENSITIVITY


Table 3

Table 4

Table 5

4800 Bauds -112 dBm

o Regulatory Bodieso FCC (United States)o IC (Canada)o ETSI (Europe, some APAC)o C-Tick (Australia)o Telec (Japan)o Anatel (Brazil)

RF Regulations


RF Regulations


o Modulateo Insert data signal into a carrier wave.o Digital data. 0 or 1

o RF Modulationo Transmitting a signal within a carrier frequency by blending an

alternating frequency or amplitude onto the carrier wave

RF Modulation


Data

Carrier

Modulated Signal

Serial Link NotionsTheory – Operating Principles


o Architecturally RS-232 is a bi-directional point to point link.o RS-232 is a popular communications interface for connecting modems and

data acquisition devices (i.e. GPS receivers, electronic balances, data loggers, ...) to computers.

o RS-232 can be plugged straight into the computer’s serial port (know as COM or Comm port).

Serial Links - RS-232


o Two independent channels are established for two-way (full-duplex) communications.

o RS-232 can also carry additional signals used for flow control (RTS, CTS) and modem control (DCD, DTR, DSR, RI).



o Unbalanced Line Driverso Each signal appears on the interface connector as a voltage with

reference to a signal ground.o The “idle” state (MARK) has the signal level negative with respect to

common whereas the active state (SPACE) has the signal level positive respest to the same reference.



o How fast can RS-232 be?o The maximum speed, according to the standard, is 20kbit/s.

However, modern equipment can operate much faster than this.o The length of the cable also plays a part in maximum speed.

The longer the cable the slower the speed at which you can obtain accurate results.A large wire capacitance and inductance limits the maximum length of the cable and/or the maximum speed; Moreover higher is the capacitance of the cable higer is the interference between two adjacent signal wire.15m @ max baudrate is commonly quoted as the maximum distance.



o SW Settingso One byte of async data has:o Start Bit = 1 (always)o Data Bits = 8 (or 7)



o Stop bits = 1 (or 2)o Parity = NONE (or EVEN or ODD)

+ 25

- 25

o What is RS-485?o RS-485 is a EIA standard interface which is very common in the data

acquisition worldo RS-485 provides balanced transmission line which also can be shared in

Multidrop mode.o It allows high data rates communications over long distances in real

world environments.o How fast can RS-485 be?o RS-485 was designed for greater distance and higher baudrates than RS-

232.o According to the standard, 100kbit/s is the maximum speed and

distance up to 4000 feet (1200 meters) can be achieved.



o Balanced Line Driverso Voltage produced by the driver appears across a pair of signal wires that

transmit only one signal. Both wires are driven opposite.o RS-485 driver has always the “Enable” direction control signal.o Differential system provides noise immunity, because much of the

common mode signal can be rejected by the receiver. So ground shifts and induced noise signals can be nullified.



o RS-485 Networko RS-485 provides Half-Duplex, Multidrop communications over a single

twisted pair cable.



MASTER SLAVE-1

SLAVE-2 SLAVE-3

o The standard specifies up to 32 drivers and 32 receivers can share a multidrop network

o Terminator resistors avoid reflected signal

o RS-485 Full-duplexo Potentially RS-485 interface can also use 4-wires to comunicate in

multidrop mode but...



TX

ENABLE

RX

TX485+TX485-

RX485+

RX485-485GND

TX

ENABLE

RX

Other device

o RS-232 vs RS-485

o The architectural difference between RS-232 and RS-485 is that 232 is a bi-directional point to point link, whereas 485 is a single channel bus.

o Electrically, each 232 signal uses a single wire with symmetric voltages about a common ground wire. 485 uses two wires to carry the single signal differentially.

o The big difference to the software is that only one device on a 485 bus can transmit at a time, whilst there is not similar limitation on RS232 because is a peer-to-peer link .

Serial Links


Network NotionsTheory – Operating Principles


o Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/IP)

Network Notions


o TCP/IP stack is base in the OSI model

Network Notions


PHYSIQUE

LIAISON

RESEAU

TRANSPORT

SESSION

PRESENTATION

APPLICATION76

5

4

3

2

1

MODELE OSI MODELE TCP/IP

ACCES RESEAU

INTERNET

TRANSPORT

APPLICATION

A

B

C

D

Different network types interconnected. = don’t depend of low level layers.

o Encapsulation:

Network Notions – TCP/IP


APPLICATION

TRANSPORT

INTERNET

ACCES RESEAU

Message

Segment

Datagramme

Trame

Réseau

Client Server

Client <->MasterServer <-> Slave

Successive encapsulation of datas from application to physical network access.

o Physical Addressing:o NIC (Network Interface Controller)= address of low level layerso Each NIC has a MAC address (6 bytes)

o Address Resolution:o The communication between 2 equipments starts by a MAC resolution address.o Example: arp = MAC resolution from an IP addresso Needs a frame « all access » for query everyone and wait for replyo Frame « all access» has @MAC dest « Broadcast » (FF-FF-FF-FF-FF-FF)



o Physical & standard layers:



APPLICATION

TRANSPORT

INTERNET

802.2 LOGICAL LINK CONTROL (LLC)

802.3MAC

802.5MAC

802.11 MAC

802.3 PHY

802.5 PHY

802.11FHSS PHY

802.11DSSS PHY

802.11aOFDM PHY

802.11bHR/DSSS PHY

GFSK PHY

802.3 802.5 802.11 ARM802.3MAC

TokenRing

CSMA/CD Wireless

PHY: Radio, Cable, Optical fibers

MAC: (CSMA/CD, CSMA/CA, Token ring, RTS/CTS etc...)


o Management of the low layers By ARM-SE:

APPLICATION

TRANSPORT

INTERNET

ACCES RESEAU

ARM

MAC

PHY

MAC

PHY

802.3

=My @IP ?

HTTP MODBUS TCPSERVER

BOOTLOADER

@MACFILTER

APPLICATION

TRANSPORT

INTERNET

802.2 LOGICAL LINK CONTROL (LLC)

802.3MAC

802.5MAC

802.11 MAC

802.3 PHY

802.5 PHY

802.11FHSS PHY

802.11DSSS PHY

802.11aOFDM PHY

802.11bHR/DSSS PHY

GFSK PHY

802.3 802.5 802.11 ARM802.3MAC

Network Notions


APPLICATION

TRANSPORT

INTERNET

ACCES RESEAU

ARM

MAC

PHY

MAC

PHY

802.3

=My @IP ?

HTTP MODBUS TCPSERVER

BOOTLOADER

@MACFILTER

Applications managed by ARM-SE server:HTTP: embedded web pagesModBusTCP Server: decapsulate ModBus RTU

messageBootloader: Firmware upgrade service

Destination MAC addresses filtering(to reduce the wireless Ethernet trafic)

Except Broadcast addressing !

DescriptionARM-SE


o Operating modes:o Ethernet, ModBus TCP Server & Serial

o Interfaceso RS232, RS485, Ethernet interfaces

o Inputs/Outputo 1 digital input & 1 digital output

ARM-SE Description


ARM-SE Description


Antenna Connector

(SMA female)

RS232 port

RJ45 Ethernet

RS485 port

Power SupplyInput/Output

LED indicators Rx, Tx, In, Out, Sys, On

Thumb wheel 16 channels

(rear side)

4 Dip switches for test mode and RS485 termination (rear side)

ARM-SE Description


Désactivé ↔ Activé1 : Mode test2 : Pull-up 2.7K3 : Pull-down 2.7K4 : Terminaison 120Ω

Selection of radio channel ortest number

DIP Switch

Thumb Wheel

o Configuration viao Webpageso AT Commandso SNMP (Firmware 10.2)

ARM-SE Description


Operating ModesARM-SE


ARM-SE Operating Modes


SERIAL

ETHERNET

GATEWAY

OPERATINGMODE

TRANSPARENT

SECURIZED

MIRROR

MODBUS

RS 485

RS 232

ETHERNET

MAC

MAC

PHY

INTERNALREGISTERS

EXTENSIONCARDS

TRANSPARENT

AT COMMANDSWEB PAGES

MODBUS RTUMODBUS TCP

o Selection of operating mode :



o Ethernet mode:o ARM-SE connected to the « NIC » with a 10 Base T cableo The « NIC » can talk anytime o Communication reliability guaranteed by :

• ACK wireless headers and repeat after randomized time• Wireless RTS/CTS (depends of the configuration)

o Datarate difference compensated by control algorithms , « Transport » layer (Typically TCP)• -> avoid flow congestion and traffic jam.



o Ethernet mode:1. Point to Point (case n°1):



Easy operating mode, default setup




Almost similar than case n°1 because the switch isolate the communications from its ports.




Operation uselessly disturbed by repeated messages from the hub

o Ethernet mode:Filters setup on destination MAC addresses :



o Ethernet mode:2. Point to Multipoints



Star Network topology:Clients can speak onlywith Access Point.

Bandwith activelyemployed.

ARM-SE

AB

ENDPOINT 2

ARM-SE

ENDPOINT 1

ENDPOINT 6

ENDPOINT 5

A

ARM-SE

AC

ENDPOINT 3

ARM-SE

AD

ENDPOINT 4

o ModBus TCP Server mode:

o Identical to a ModBus slave solicited by a master/client device.o Allow communication between an Ethernet device with ModBus TCP protocol and

ModBus RTU slaves.




o ModBus Environment :



Communication between devices connected to different kinds of buses

Good for read/write of Inputs / Outputs


o MODBUS Reminder• The request:

• The response:

In case of error, the data include an exception code indicating the error nb.




o MODBUS Reminder• Function codes:




o MODBUS Reminder• ModBus messages:

• Modbus RTU

• Modbus TCP



o ModBus TCP Server mode:o Use of the ModBus TCP/ModBus RTU gateway:

• ARM-SE Server ModBus TCP decapsulate the message and send it to different possible targets.



o ModBus TCP Server mode:o Limited number of client connections on the server (need resources):

• Max 2 client applications (or 2 clients). • Each client use a different port (TCP 502: default port for ModBus TCP protocol)



o ModBus TCP Server mode:o Affectation of the TCP ports according to the target

• The TCP port forwards the connection to the target.



PORT 80 PORT 502 PORT 503

TARGETS

MODB

US TC

P SE

RVER

H

TTP

IP

TCP

@IP Y

o ModBus TCP Server mode:o Query of the targets :



X

ARM-SE

RS485

RS232MODBUSTCP RTU

3

12

R

ADIO

CHANNEL Z

ARM-DAARM-D

ARM-LP

R

ADIO

CHA

NNEL

Y

ARM-LPARM-LP 3

SERVER@IP B

MODBUS TCPCONSOLE

TCP PORT: 502

MODBUS TCPCONSOLE

TCP PORT: 503

CLIENTS@IP A

With different radio channelsIs possible to communicate

with different cluster of slaves

o ModBus TCP Server mode:o Query of a remote ModBus TCP server

• Via an ARM-SE in transparent operating mode



CLIENTS@IP A

X

ARM-SE

RS485

RS232MODBUS

TCP RTU

3

12

R

ADIO

CHANNEL Z

ARM-DAARM-D

SERVER@IP C

@IP BTCP PORT: 503

MODBUS TCPCONSOLE@IP B

TCP PORT: 502

MODBUS TCPCONSOLE

R

ADIO CHANNEL X

o ModBus TCP Server mode:o Configuration:



o Serial mode:1. Transparent mode

– The radio modem goes in wireless Tx as soon its receive a byte on its serial port (+ optional delay before transmission).

– Transmission (Tx) while the serial buffer (1024B) contains Bytes.– Delay after Tx before to go back to reception (Rx).– RTS/CTS RS232 flow control




TOTOBits de synchroTOTOTOTO

Equipment A Equipment B

ARM

ARM

ARM-SE ARM-SE


o Serial mode:1. Securized mode




TOTOTOTO

Equipment A Equipment B

HeaderTOTOCRC CRCACKHeader

ARM

CODE

ARM

ARM

Repeater

Works also with repeater



HeaderModbusModbus

Equipment A

S ToR ou Ana

E ToR ou Ana

ARM-DARM-DAARM-X

Header Modbus Response

ARM

Modbus Response

ARM

RS232RS485

ARM-SE

o Serial mode:1. Modbus mode

Radio SettingsARM-SE


o To establish a link radios should be in same channel.

ARM-SE Radio


Canal Fréquence (MHz) Canal Fréquence

(MHz)

0 869.800 8 868.425 Puiss. Max. : 25mW

Duty Cycle : 1%1 868.075 9 868.4752 868.125 A 868.5253 868.175 B 869.850 Puiss. Max. : 5mW

Duty Cycle : 100%4 868.225 C 869.9005 868.275 D 869.475 Puiss. Max. :

500mWDuty Cycle : 10%

6 868.325 E 869.5257 868.375 F 869.575

o Configuration radio

ARM-SE Radio


o Repeating and routing table:

ARM-SE Radio


ARM-SE

AB

ENDPOINT 2

ARM-SE D

ARM-SE

C

MY @@DESTC1EXPC1DESTC2EXPC2DESTC3EXPC3DESTC4EXPC4DEST

C

AEDA


D

EA

AC


EA


FB


BF


AEFBBF F

ARM-SEENDPOINT 4

ARM-SE

AA

ENDPOINT 1

E

ARM-SEENDPOINT 3

User defines his path

o Addressing Principle :

ARM-SE Radio


@Exp @Dest Data

YES

NO=? SEND DATA

ON SERIAL PORT

NO

=?

=?

=?

NO

NOMy@ @Dest Data

REPEAT RADIO MSG.KEEP @ DEST

AND REPLACE @EXP

YES

My @@Dest

C1C2

C3C1 EXPC1 DESTC2 EXPC2 DESTC3 EXPC3 DEST

@Exp @Dest Data My @(@Dest)

C1C2

C3

C1 EXPC1 DESTC2 EXPC2 DESTC3 EXPC3 DEST

MODEM AMODEM BREPEATER

• The transmitting modem adds its local address and destination address to the radio frame.

• Modems receiving the radio frame compare the 2 addresses added to the pairs of configured addresses.

• If the additional addresses are identical to a configured pair of addresses, the message is recognised by the modem; otherwise the modem does not recognise the radio frame.

• The modem recognising the message compares the destination address for the message with its local address.

• If they are identical the message is sent over the serial link; otherwise, the modem returns the message by radio, exchanging the message’s local address with its own local address.

ExtrasARM-SE


o Alerts via emailo Watchdogo Input/Output

ARM-SE Extras


o Dataloggingo Interoperability with ARM_IOLPo Modbus RTU Slaves sleep

• ARM-SE poll them every Tcycle• Users get information via Modbus or webpages

ARM-SE Extras


o Test modes

ARM-SE Extras


o Firmware Update

ARM-SE Extras


Thank youARM-SE


Luis Martinez [email protected] Ruzzin [email protected]

www.atim.com Tel: 04 76 95 50 65

mailto:[email protected]

mailto:[email protected]

http://www.atim.com/

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