Westermo RM-80 User Manual

Reference Guide

6193-4201

RM-80

Westermo Teleindustri AB • 2006

©

Wireless Ethernet

Radio Modem

www.westermo.com

Thank you for your selection of the RM-80 Wireless Ethernet Modem.
We trust it will give you many years of valuable service.

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ATTENTION!

Incorrect termination of supply wires may
cause internal damage and will void warranty.
To ensure your RM-80 enjoys a long life,

double check ALL your connections with the users manual

before turning the power on.

Caution!

For continued protection against risk of fire, replace the internal module fuse only with
the same type and rating.

CAUTION:

To comply with FCC RF Exposure requirements in section 1.1310 of the FCC Rules,

antennas used with this device must be installed to provide a separation distance of at

least 20 cm from all persons to satisfy RF exposure compliance.
DO NOT:
… operate the transmitter when someone is within 20 cm of the antenna
… operate the transmitter unless all RF connectors are secure and any open connectors

are properly terminated.
… operate the equipment near electrical blasting caps or in an explosive atmosphere

All equipment must be properly grounded for safe operations.
All equipment should be serviced only by a qualified technician.

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3

Important Notice

WESTERMO products are designed to be used in industrial environments, by experi-

enced industrial engineering personnel with adequate knowledge of safety design
considerations.

WESTERMO radio products are used on unprotected license-free radio bands with radio

noise and interference. The products are designed to operate in the presence of noise
and interference, however in an extreme case, radio noise and interference could
cause product operation delays or operation failure. Like all industrial electronic
products, WESTERMO products can fail in a variety of modes due to misuse, age, or
malfunction. We recommend that users and designers design systems using design
techniques intended to prevent personal injury or damage during product operation,
and provide failure tolerant systems to prevent personal injury or damage in the event
of product failure. Designers must warn users of the equipment or systems if ade­quate protection against failure has not been included in the system design. Designers
must include this Important Notice in operating procedures and system manuals.

These products should not be used in non-industrial applications, or life-support systems,

without consulting WESTERMO Technologies first.

1. A radio license is not required in some countries, provided the module is installed
using the aerial and equipment configuration described in the RM-80 Installation Guide.
Check with your local distributor for further information on regulations.

2. Operation is authorized by the radio frequency regulatory authority in your country
on a non-protection basis. Although all care is taken in the design of these units, there
is no responsibility taken for sources of external interference. Systems should be
designed to be tolerant of these operational delays.

3. To avoid the risk of electrocution, the aerial, aerial cable, serial cables and all terminals
of the RM-80 module should be electrically protected. To provide maximum surge
and lightning protection, the module should be connected to a suitable earth and the
aerial, aerial cable, serial cables and the module should be installed as recommended
in the Installation Guide.

4. To avoid accidents during maintenance or adjustment of remotely controlled equip­ment, all equipment should be first disconnected from the RM-80 module during
these adjustments. Equipment should carry clear markings to indicate remote or auto­matic operation. E.g. “This equipment is remotely controlled and may start without
warning. Isolate at the switchboard before attempting adjustments.”

5. The RM-80 module is not suitable for use in explosive environments without addi­tional protection.

4

6193-4201

Chapter One INTRODUCTION

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The RM-80 Wireless Ethernet module provides wireless connections between Ethernet
devices or Ethernet wired networks (LAN’s). It has an internal 869 MHz wireless trans­ceiver, which can be used without a radio license in Europe and South Africa. The RM-80
transmits RF power of 500mW, requiring the transmit duty-factor be limited to 10%.

The RM-80 has a standard RJ45 Ethernet connection which will operate at up to
100Mbit/sec. The module will transmit the Ethernet messages on the wireless band at up
to 76 Kbit/sec.

1.1 Network Topology

The RM-80 is an Ethernet device, and must
be configured as part of an Ethernet net­work. Each RM-80 must be configured as:

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… an “Access Point” or a “Client”, and
… a “Bridge” or a “Router”.

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You can also connect to the RM-80 via a RS-232 or RS-485 serial port using PPP
(point-to-point) protocol. PPP allows the RM-80 to connect serial communications
into the Ethernet network.

Access Point vs Client

The Access Point unit acts as the
“wireless master” unit. The Access
Point sets up the wireless links
to the Client units, and controls

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the wireless communications. The
first diagram shows two Ethernet
devices being linked. One RM-80
is configured as an Access Point and one as
a Client – in this example it doesn’t mater
which unit is the Access Point.

The second diagram shows an existing LAN
being extended using RM-80’s. In this exam­ple, the Access Point should be configured at
the LAN end – although the wireless link will
still work if the Client is at the LAN end.

An Access Point can connect to multiple
Clients. In this case, the Access Point should
be the “central” unit.

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5

An Access Point could be used as a “Repeater” unit to connect two RM-80 Clients which

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do not have direct reliable radio paths.

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Bridge vs Router

Each RM-80 is configured
with an IP address for the

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Ethernet side, and
another for the wireless

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side.
A Bridge connects

devices within the same
Ethernet network – for example, extending an existing Ethernet LAN. For a Bridge, the IP
address for the wireless side is the same as the Ethernet side.

A Router connects devices

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on different LAN’s. The IP
addresses for the Ethernet
and wireless sides are dif­ferent.

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In the above example, the wireless link is part of LAN A, with the Client unit acting as a
Router between LAN A and LAN B. Alternately, the Access Point could be configured as
a Router – the wireless link is then part of LAN B.

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There is limit of two Routers within the same radio network. There is no limit to the
number of Bridges in the same network – although there is a limit of 255 Client units
linked to any one Access Point.

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1.2 Getting Started Quickly

Most applications for the RM-80 require little configuration. The RM-80 has many sophis­ticated features, however if you don’t require these features, this section will allow you to
configure the units quickly.

First, read Section 2, “Installation”. The RM-80 requires an antenna and a power supply.

… Power the RM-80 and make an Ethernet connection to your PC (for further informa-

tion on how to do this, refer to section 3.3)
… Set the RM-80 address settings as per section 3.4
… Save the configuration – the RM-80 is now ready to use.

Before installing the RM-80, bench test the system. It is a lot easier to locate problems
when the equipment is all together.

There are other configuration setting which may or may not improve the operation of
the system. For detail on these settings, refer to section 3.

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7

Chapter Two INSTALLATION

2.1 General

The RM-80 module is suitable for DIN-rail mounting. Terminals will accept wires up to 12
gauge (2.5 sqmm) in size.

All connections to the module must be SELV. Normal 110-240V mains supply
should not be connected to any terminal of the RM-80 module. Refer to Section

2.3 Power Supply.
Before installing a new system, it is preferable to bench test the complete system.

Configuration problems are easier to recognize when the system units are adjacent.
Following installation, the most common problem is poor communications caused by
incorrectly installed antennas, or radio interference on the same channel, or the radio
path being inadequate. If the radio path is a problem (ie path too long, or obstructions in
the way), then higher performance antennas or a higher mounting point for the antenna
may rectify the problem. Alternately, use an intermediate RM-80 Module as a repeater.

Each RM-80 module should be effectively earthed via the “GND” terminal on the RM-80
module – this is to ensure that the surge protection circuits inside the RM-80 module
are effective.

2.2 Antenna Installation

The RM-80 module will operate reliably over large distances up to 5km “line-of-sight”.
The distance which may be reliably achieved will vary with each application – depending
on the transmit power (user configurable), type and location of antennas, the degree of
radio interference, and obstructions (such as hills or trees) to the radio path.

To achieve the maximum transmission distance, the antennas should be raised above
intermediate obstructions so the radio path is true “line of sight”. The modules will oper­ate reliably with some obstruction of the radio path, although the reliable distance will
be reduced. Obstructions which are close to either antenna will have more of a blocking
affect than obstructions in the middle of the radio path. For example, a group of trees
around the antenna is a larger obstruction than a group of trees further away from the
antenna. The RM-80 modules provide a diagnostic feature which displays the radio signal
strength of transmissions.

Line-of-sight paths are only necessary to obtain the maximum range. Obstructions will
reduce the range, however may not prevent a reliable path. A larger amount of obstruc­tion can be tolerated for shorter distances. For very short distances, it is possible to
mount the antennas inside buildings. An obstructed path requires testing to determine if
the path will be reliable – refer the section 6 of this manual.

Where it is not possible to achieve reliable communications between two RM-80 mod­ules, then a third RM-80 module may be used to receive the message and re-transmit it.
This module is referred to as a repeater. This module may also have a host device con­nected to it.

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An antenna should be connected to the module via 50 ohm coaxial cable (eg RG58,
RG213 or Cellfoil) terminated with a male SMA coaxial connector. The higher the
antenna is mounted, the greater the transmission range will be, however as the length
of coaxial cable increases so do cable losses. For use on unlicensed frequency channels,
there are several types of antennas suitable for use. It is important antenna are chosen
carefully to avoid contravening the maximum power limit on the unlicensed channel – if
in doubt refer to an authorized service provider.

The net gain of an antenna/cable configuration is the gain of the antenna (in dBi) less the
loss in the coaxial cable (in dB).

The maximum net gain of the antenna/cable configuration permitted is 0dB.

The net gain of the antenna/cable configuration is determined by adding the antenna gain
and the cable loss. For example, a 6 element Yagi with 20metres of RG58 has a net gain
of 0dB (10dB – 10dB).

Connections between the antenna and coaxial cable should be carefully taped to prevent
ingress of moisture. Moisture ingress in the coaxial cable is a common cause for prob­lems with radio systems, as it greatly increases the radio losses. We recommend that the
connection be taped, firstly with a layer of PVC Tape, then with a vulcanizing tape such as
“3M 23 tape”, and finally with another layer of PVC UV Stabilized insulating tape. The first
layer of tape allows the joint to be easily inspected when trouble shooting as the vulcan­izing seal can be easily removed.

Where antennas are mounted on elevated masts, the masts should be effectively earthed
to avoid lightning surges. For high lightning risk areas, surge suppression devices between
the module and the antenna are recommended. If the antenna is not already shielded
from lightning strike by an adjacent earthed structure, a lightning rod may be installed
above the antenna to provide shielding.

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9

2.2.1 Dipole and Collinear antennas.

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A collinear antenna transmits the same amount of radio power in all directions – as
such that are easy to install and use. The dipole antenna with integral 5m cable does not
require any additional coaxial cable, however a cable must be used with the collinear
antennas.

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Collinear and dipole antennas should be mounted vertically, preferably 1 metre away
from a wall or mast to obtain maximum range.

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2.2.2 Yagi antennas.

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A Yagi antenna provides high gain in the forward direction, but lower gain in other direc­tions. This may be used to compensate for coaxial cable loss for installations with mar­ginal radio path.

The Yagi gain also acts on the receiver, so adding Yagi antennas at both ends of a link pro­vides a double improvement.

Yagi antennas are directional. That is, they have positive gain to the front of the antenna,
but negative gain in other directions. Hence Yagi antennas should be installed with the
central beam horizontal and must be pointed exactly in the direction of transmission to
benefit from the gain of the antenna. The Yagi antennas may be installed with the elements
in a vertical plane (vertically polarized) or in a horizontal plane (horizontally polarized).
For a two station installation, with both modules using Yagi antennas, horizontal polariza­tion is recommended. If there are more than two stations transmitting to a common
station, then the Yagi antennas should have vertical polarization, and the common (or
“central” station should have a collinear (non-directional) antenna.

Also note that Yagi antennas normally have a drain hole on the folded element – the
drain hole should be located on the bottom of the installed antenna.

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11

2.3 Power Supply

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The RM-80 module can be powered from a 10 – 30VDC power supply. The power sup­ply should be rated at 1 Amp.The nnegative side of the supply should be connected to a
good “ground” point for surge protection. The supply negative is connected to the unit
case internally.

The positive side of the supply must not
be connected to earth. The DC sup­ply may be a floating supply or negatively
grounded. The power requirements of the
RM-80 unit is 280mA @ 12V or 150mA
@ 24VDC. This is inclusive of radio and

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2.4 Serial Connections

2.4.1 RS-232 Serial Port

The serial port is a 9 pin DB9 female and provides for connection to a host device
as well as a PC terminal for configuration, field testing and for factory testing.
Coomunication is via standard
RS-232. The RM-80 is config­ured as DCE equipment with
the pinouts detailed below.

Hardware handshaking using
the CTS/RTS lines is provided.
The CTS/RTS lines may be

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may be configured to reflect
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12

6193-4201

DB9 Connector Pinouts

Pin Name Direction Function

1 DCD Out Data carrier detect –

2RD Out Transmit Data – Serial Data Output

3TD In Receive Data – Serial Data Input

4 DTR In Data Terminal Ready –

5 SG Signal Ground

6 DSR Out Data Set Ready – always high when unit is powered on.

7 RTS In Request to Send –

8 CTS Out Clear to send –

9RI Ring indicator –

2.4.2 RS-485 Serial Port

The RS-485 port provides for communication between the RM-80 unit and its host device
using a multi-drop cable. Up to 32 devices may be connected in each multi-drop network.

As the RS-485 communication medium is shared, only one of the units on the RS-485
cable may send data at any one time. Thus communication protocols based on the RS­485 standard require some type of arbitration.

RS-485 is a balanced, differential standard but it is recommended that shielded, twisted
pair cable be used to interconnect modules to reduce potential RFI. It is important to
maintain the polarity of the two RS-485 wires. An RS-485 network should be wired as
indicated in the diagram below and terminated at each end of the network with a 120
ohm resistor. On-board 120 ohm resistors are provided and may be engaged by operat­ing the single DIP switch in the end plate next to the RS-485 terminals. The DIP switch
should be in the “1” or “on” position to connect the resistor. If the module is not at one
end of the RS-485 cable, the switch should be off.

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6193-4201

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14

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2.5 Discrete (Digital) Input/Output

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The RM-80 has one on-board discrete/digital I/O channel. This channel can act as either
a discrete input or discrete output. It can be monitored, or set remotely, or alternatively
used to output a communications alarm status.

If used as an “input”, the I/O channel is suitable for voltage free contacts (such as
mechanical switches) or NPN transistor devices (such as electronic proximity switches).
PNP transistor devices are not suitable. Contact wetting current of approximately 5mA
is provided to maintain reliable operation of driving relays.

The digital input is connected between the “DIO” terminal and common “COM”. The I/O
circuit includes a LED indicator which is lit when the digital input is active, that is, when
the input circuit is closed. Provided the resistance of the switching device is less than 200
ohms, the device will be able to activate the digital input.

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a LED indicator which is lit when the digital output is active.

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6193-4201

15

Chapter Three OPERATION

3.1 Start-up

“Access Point” Start-up

An Access Point unit starts and immediately begins transmitting periodic messages called
beacons. These beacon messages are messages contain information for Clients on how to
establish a link with the Access Point.

Any Client that hears the messages, which are not already linked to another Access Point
unit, will respond and links will be established between the new Access Point and these
Clients.

“Client” Start-up

When a Client powers up, it immediately scans for messages from Access Point units. The
Client will continue to scan for twice the configured beacon interval in the Client. During
the scan, the RX led will flicker now and again indicating messages received, perhaps from
an Access Point. If the Client finds suitable Access Points during the scan, it will then
attempt to establish a link with the Access Point with the strongest radio signal.

Link Establishment

When the Client wishes to establish a link with an Access Point it follows a two step
process. The first step is “authentication”. During this step the Client and Access Point
check if they can establish a secure link, based upon the configured security encryption.

Once the Client has been authenticated, it will then request a link. This step is called
“association”.

While no links have been established, the LINK led will be OFF. Once a single link has
been established, the LINK led is ON.

After the link is established, data may be transferred in both directions. The Access Point
will act as a master-unit and will control the flow of information to the Clients linked to
it.

The maximum number of 255 Clients may be linked to an Access Point.

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6193-4201

How a Link connection is lost

The RM-80 will reset the Link if:
… Excessive retries:

When a RM-80 unit transmit a wireless message to another unit, the destination unit
will transmit back an acknowledgment. If the source unit does not receive an acknowl­edgment, it will re-send the message – this is known as a “re-try”. Both Access Point
and Client will drop the link if the number of retries for a single packet exceeds (7)
times. Packets are retransmitted according to an increasing time delay between retries,
with each attempt on a different frequency.

… Inactivity:

During periods of inactivity, Clients will periodically check that the link to the Access
Point remains intact. This process is called “reassociation”, and will occur approxi­mately (6) beacon intervals after the last packet was sent to the Access Point. If a
Client unit does not get a response from its Access Point, it will retry the reassociat­ing request (7) times before resetting the link. If an Access Point does not receive any
traffic from a Client, including reassociating requests, within (12) beacon intervals, the
Access Point will reset the link.

After a Client has reset it’s Link status, it will start scanning for an Access Point, as if it
has just started up.

LED Indication

The following table details the status of the indicating LEDs on the front panel under

normal operating conditions.

LED Indicator Condition Meaning

OK GREEN Normal Operation

OK RED Supply voltage too low.

Radio RX GREEN flash Radio receiving data

Radio RX RED flash Weak radio signal

Radio TX Flash Radio Transmitting

Radio LINK On On when a radio communications link is established

Radio LINK Off Communications failure or radio link not established

Radio LINK GREEN flash

RED flash

LAN ON Link Established on Ethernet port

LAN Flash Activity on Ethernet port.

Serial GREEN flash RS-232 Serial Port Activity

Serial RED flash RS-485 Serial Port Activity

DIO On Digital Output ON or Input is grounded.

DIO Off Digital Output OFF and Input is open circuit.

Serial Port Receiving

CTS low

The Ethernet RJ45 port incorporates two indication LEDs. The LINK LED comes on
when there is a connection on the Ethernet port, and will blink off briefly when activity is
detected on the Ethernet Port. The 100MB LED indicates that the connection is at
100 MBit/Sec. The 100MB LED will be off for 10MB/Sec connection.

Other conditions indicating a fault are described in Chapter Six Troubleshooting.

6193-4201

17

3.2 Default Configuration

The default factory configuration of the RM-80 is
… Bridge/Client
… IP address192.168.0.1XX, where XX is the last two digits of the serial number (the

default IP address is shown on the printed label on the back of the module)
… netmask 255.255.255.0
… Username is “user” and the default password is “user”
The RM-80 will temporarily load some factory-default settings if powered up with the

Factory Default switch (on the end-plate of the module) in SETUP position. In the posi­tion, wireless operation is disabled. The previous configuration remains stored in memory
and will only change if a configuration parameter is modified and the change saved.

Do not forget to set the switch back to the RUN position and cycle power at the con­clusion of configuration for resumption of normal operation.

3.3 Configuring the Unit for the First Time

The RM-80 has a built-in webserver, containing webpages for analysis and modification
of configuration. The configuration can be accessed using Microsoft® Internet Explorer.
This program is shipped with Microsoft Windows or may be obtained freely via the
Microsoft® website.

Configuration of IP address, gateway address and subnet mask may also be accessed via
the RS-232 serial port.

Accessing Configuration for the first time

There are two methods for accessing the configuration inside a RM-80. The first method
requires changing your computer settings so that the configuring PC is on the same
network as the RM-80 with factory default settings. This is the preferred method
and is much less complicated than the second method. You will need a “straight-through”
Ethernet cable between the PC Ethernet port and the RM-80. The factory default
Ethernet address for the RM-80 is 192.168.0.1XX where XX are the last two digits of
the serial number (check the label on the back of the module).

The second method requires setting an IP address in the RM-80 such that it is accessible
on your network without having to change your network settings.

3.3.1 Set PC to same network as RM-80

Connect the Ethernet cable between unit and the PC configuring the module.
… Set the Factory Default Switch to the SETUP position. This will always start the RM-

80 with Ethernet IP address 192.168.0.1XX, subnet mask 255.255.255.0, gateway IP

192.168.0.1 and the radio disabled. Do not forget to set the switch back to the RUN

position and cycle power at the conclusion of configuration for resumption of normal

operation.
… Power up the RM-80 module.
… Open “Network Settings” on your PC under Control Panel. The following description

is for Windows XP – earlier Windows operating systems have similar settings.
… Select Internet Protocol (TCP/IP) and click on Properties.

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