Laird CL4790 Hardware Integration Manual

CL4790

HARDWARE INTEGRATION GUIDE
VERSION 3.0

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FCC Notice

WARNING: This device complies with Part 15 of the FCC Rules. Operation is subject to the
following two conditions: (1) This device may not cause harmful interference and (2) This device
must accept any interference received, including interference that may cause undesired
operation.

RF Exposure/Installation Instructions

WARNING: To satisfy FCC RF exposure requirements for mobile transmitting devices, this
equipment must be professionally installed such that the end user is prevented from replacing
the antenna with a non-approved antenna. The end user should also be prevented from being
within 20cm of the antenna during normal use with the exception of hands, feet, wrists and
ankles.

The preceding statement must be included as a CAUTION statement in manuals for OEM
products to alert users on FCC RF Exposure compliance.

Caution: Any change or modification not expressly approved by Laird could void the user’s authority to
operate the equipment.

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Version

Date

Changes

Approved By

1.0

Initial Release

Chris Downey

1.1

Changes and Revisions

Chris Downey

2.0

02 Aug 2013

Major changes and revisions; updated format and data

Chris Downey

3.0

18 Dec 2013

Separated Hardware Integration Guide (HIG) from User
Guide information (created two separate documents).
Add Related Documents section.

Sue White

REVISION HISTORY

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CONTENTS

Revision History ............................................................................................................................................ 3

Contents ....................................................................................................................................................... 4

CL4790 RF Transceiver ................................................................................................................................. 5

Overview ........................................................................................................................................................ 5

Features ........................................................................................................................................................ 5

Detailed Specifications .............................................................................................................................................. 6

Status LEDs ................................................................................................................................................... 7

Serial Interface ............................................................................................................................................. 8

Hardware Flow Control ........................................................................................................................................... 11

Hardware .................................................................................................................................................... 12

Mechanical Drawing ............................................................................................................................................... 12

Approved Antenna List ........................................................................................................................................... 12

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 Masterless: True peer-to-peer; each module can communicate with any other module within its range

and network

 API commands to control packet routing and acknowledgement on a packet-by-packet basis
 Durable industrial grade enclosure
 Transparent operation; supports any legacy system
 Transmits around corners, through walls
 Reliable communication with serial UART speeds up to 115.2 Kbps
 Point-to-Point and Point-to-Multipoint setups

CL4790 RF TRANSCEIVER

The CL4790 transceiver is a Frequency Hopping Spread Spectrum (FHSS) radio designed for license-free
operation in the 900 MHz Industrial, Scientific, and Medical (ISM) unlicensed band. The radio sustains a
standard asynchronous serial data stream between two or more radios. Housed in a compact and rugged die­cast enclosure, the radio is equipped to replace miles of serial cable with its wireless link. The radio features
an RS232 or RS485 interface for integration into legacy data systems.

Overview

The CL4790 uses Frequency Hopping Spread Spectrum technology, where the units “hop” from frequency to
frequency many times per second using a specific hop pattern applied to all the transceivers in the same
network. A distinct hopping pattern is provided for each Channel Number, thereby allowing multiple
networks to co-exist in the same area with limited interference.

CL4790 transceivers operate in a Masterless architecture. When a CL4790 has data to transmit, it will enter
transmit mode and start transmitting a sync pulse intended for an individual radio or broadcast to all
transceivers within the same network and range. Intended receivers synchronize to this sync pulse, a session
begins and data is transmitted. This instinctive dynamic peer-to-peer networking architecture enables several
transceiver pairs to carry on simultaneous conversations on the same network.

CL4790s implement a proprietary communication protocol to provide secure data transmissions. Using FHSS
technology ensures data reliability over long distances.

The CL4790 transceivers use the 900 MHz ISM license free frequency band, which requires no additional
certifications when designing into a new or legacy data system.

Each unit is small and easily portable for use in mobile and temporary settings as well as fixed installations.
The CL4790 configuration software enables custom configurations based on unique application requirements.

This document contains information about the hardware and software interface between a Laird CL7490
transceiver and an OEM host. Information includes the theory of operation, specifications, serial interface
definition, security information and mechanical drawings. The OEM is responsible for ensuring the final
product meets all appropriate regulatory agency requirements listed herein before selling any product.

Note: CL4790 modules are referred to as the “radio” or “transceiver”. Individual naming differentiates

product -specific features. The host (PC, Microcontroller or any connected device) is “OEM host.”

Features

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INTERFACE

Serial Interface Connector

DB-9 Male (RS232), Terminal Block (RS485)

RF Connector

RPSMA Jack

Serial Interface Data Rate

Baud rates from 1200 bps to 115.2 Kbps

Power Consumption

400 mA @ 12 VDC

Channels

US/Canada: 32 channels
Australia: 8 channels

Supported Network
Topologies

Point-to-Point, Point-to-Multipoint
Security

One byte System ID. 56-bit DES encryption key.

Interface Buffer Size

Input/Output: 256 bytes each

OPERATIONAL

Frequency Band

902 – 928 MHz (US/Canada)
915 – 928 MHz (US/Canada, Australia)

RF Data Rate

76.8 Kbps fixed

Host Data Throughput

20.5 Kbps maximum

RF Technology

Frequency Hopping Spread Spectrum (FHSS)

EEPROM write cycles

20000

Hop Period

50 ms

Output Power

Conducted (no antenna)

EIRP (3dBi gain antenna)

CL4790-1000

743 mW typical

1486 mW typical

Supply Voltage

CL4790-1000: 7-18VDC; 400 mA

Receiver Sensitivity

-100dBm typical @ 76.8 kbps RF Data Rate

Range, Line of Sight
(based on 3dBi gain
antenna)

Max. 1500 feet (450 m) indoors; Max. 20 miles (32 km) line-of-sight

POWER SETTINGS (Input Voltage: 12 v DC)

Transmit – Full Duty Cycle

Max Power Setting

Current (mA)

dBm

mW

Low

157

10

10

Quarter

225

23

200

Half

280

26

400

Full

365

28

743

Receive – Transceiver in
Idle

Max Power Setting

Current (mA)

Low

50

Quarter

50

Half

50

Full

50

ENVIRONMENTAL

Temperature (Operational)

-40° C to +80° C

Temperature (Storage)

-50° C to +85° C

Humidity (Non­Condensing)

10% to 90%

Detailed Specifications

Table 1: CL4790-1000 Specifications

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PHYSICAL

Dimensions

4.4 x 2.7 x 1.4 inches

Weight

6 oz. (170 g)

CERTIFICATIONS

FCC Part 15.247

CL4790-1000: KQLAC4490

Industry Canada (IC)

CL4790-1000: 2268C-AC44901000

Caution!

ESD Sensitive Component. Use proper ESD precautions when handling this device to prevent
permanent damage.
External ESD protection is required to protect this device from damage as required to pass IEC
61000-4-2 or ISO 10605 based on end system application.

LED

Color

Description

Pwr

Green

On. Indicates the unit is powered up.

Link

Red

On. Indicates the CL4790 is In Session.

RXD

Green

When flashing, indicates the CL4790 is receiving data.

TXD

Red

When flashing, indicates the CL4790 is transmitting data.

STATUS LEDS

CL4790

Figure 1: CL4790 Status LEDs

Table 2 describes each of the CL4790 Status LEDs.

Table 2: CL4790 Status LEDs

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DB9 Pin

Signal Name

Description

Direction

1

DCD

Data Carrier Detect

Out

2

TXD (RXD with respect to DTE)

Transmit Data

Data Out to Host

3

RXD (TXD with respect to DTE)

Receive Data

Data In to CL4790

4

DTR

Data Terminal Ready

In

5

GND

Ground

-

6

DSR

Data Set Ready

Out

7

RTS

Request to Send

In

8

CTS

Clear to Send

Out

9

RI

Ring Indicator

Out

SERIAL INTERFACE

 CL4790 Serial Interface
 Hardware Flow Control

The CL4790 supports the following protocols, which are separate products:

 RS232
 RS485

CL4790 Serial Interface

RS232

Figure 2: CL4790-RS232

RS232 is a single-ended data transmission protocol. The RS232 signals are represented by voltage levels with

respect to a system common (power/logic ground). The “idle” state (MARK) has the signal level negative with
respect to common, and the “active” state (SPACE) has the signal level positive with respect to common.

Table 3: CL4790 DB9 Male Connector Pinout (as defined at the CL4790)

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Figure 3: DTE to DCE interface (all signals with
respect to DTE)

Figure 4: DCE to DCE interface (all signals with
respect to DTE)

Interfacing to Other RS232 Equipment

The CL4790 is a DCE (Data Communications Equipment) device. Typically, devices like PCs are considered
DTE (Data Terminal Equipment) devices while peripheral devices are classified as DCE. A DCE device can
interface to a DTE device using a straight-through serial cable. When interfacing two DCE (or two DTE)
devices together, a null modem cable (or crossover cable) is required to swap the pins and convert the signals
accordingly.

Note: When using a pair of CL4790s to connect a PC to a peripheral unit, if you previously used a straight-

through serial cable to connect your PC to your peripheral device, you’ll need to use a straight­through serial cable between the PC and the CL4790 and a null modem adapter, or cross-over cable,
between the other CL4790 and the peripheral device.

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Table 4: CL4790 Terminal Block Pinout

Terminal Block Pin

Signal Name

Description

1

VCC

6-18V (1.3A required)

2

485 -

485B

3

N/C

No Connect

4

N/C

No Connect

5

485 +

485A 6 GND

Ground

RS485

Figure 5: CL4790-RS485

The RS485 interface uses a Differential Data Transmission that can help nullify the effects of ground shifts
and induced noise signals that can appear as common mode voltages on a network.

The CL4790 uses a RS485 (2-wire Half Duplex) multi-drop interface. Typically, a RS485 bus consists of a
master and several slaves. The nodes have unique addresses and can send addressed packets to specific
nodes. Because the bus is half duplex, no two nodes should try to talk at the same time. The CL4790 does
not have a RS485 address; therefore it transmits all RS485 traffic over the RF. Conversely, as soon as the
CL4790 receives a packet over the RF, it transmits the packet over the RS485 bus.

Note: When using RS485 (2-wire Half Duplex), a RS485 to RS232 converter is required to configure the unit.

Laird recommends a B&B Electronics 4WSD9R converter to translate RS485 to RS232.

Figure 6: RS232-485 Converter

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Note: Many simple 2- or 4-wire converters do not provide hardware flow control capabilities and therefore

require you to disable handshaking by setting Handshaking to None in the Laird Configuration Utility.
Check with your converter manufacturer for any specific requirements.

Hardware Flow Control

Flow control refers to the control of data flow between the host and the CL4790. It is the means of handling
data in the transmit/receive buffer of the CL4790 interface and it determines the throttling of data flow
between the host and the CL4790. Often in serial communication, one device is capable of sending data
much faster than the other can receive. Flow control allows the slower device to tell the faster device to
pause and resume data transmission. Because flow control signals CTS and RTS are used by the CL4790 and
its host

The CL4790 controls the Clear to Send (CTS) output to the OEM host. The state of the CTS pin is based on
the amount of data in the interface buffer. If the buffer is below the maximum limit, the transceiver holds
CTS logic Low to signal to the OEM host that data can be accepted over the serial interface safely. If the
buffer is full, then CTS transitions logic High to signal to the OEM host that additional data sent over the
serial bus has the potential to be lost due to buffer overflow.

locally

(rather than over the air), one CL4790 cannot tell the other CL4790 to slow down or speed up.

Ready to Send (RTS) is an input to the CL4790 from the OEM host. When the
the software configuration of the CL4790, the transceiver checks the status of RTS before attempting to send
received RF data to the OEM host. If RTS is logic Low, the transceiver sends data to the OEM host. If RTS is
logic High, it does not send data to the host.

Note: CTS is always enabled by default. RS485 Interface does not support Hardware flow control.

RTS is high by default on the CL4790. If RTS Enable is enabled, the CL4790 does not transmit data

out the serial interface unless the RTS line is driven low by the OEM host.

Tip

Can I implement a design using just Txd, Rxd and Gnd (Three-wire Interface)?

Yes. However, Laird strongly recommends that your hardware monitor the CTS pin of the radio.
CTS transitions logic High by the radio when its interface buffer is getting full. Your hardware
should stop sending data over the serial interface at this point to avoid a buffer overrun (and
subsequent loss of data).

You can perform a successful design without monitoring CTS. However, you need to take into
account the amount of latency the radio adds to the system, any additional latency caused by
Transmit Retries or Broadcast Attempts, how often you send data, non-delivery network
timeouts, and interface data rate. Polled type networks, where a centralized host requests data
from the surrounding hosts and the surrounding hosts respond, are good candidates for
avoiding the use of CTS. This is because no one transceiver can monopolize the RF link.
Asynchronous type networks, where any radio can send to another radio at any point in time,
are much more difficult to implement without the use of CTS.

RTS Enable

option is selected in

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Laird Part #

Manufacturer Part #

Manufacturer

Type

Gain (dBI)

CL4790-1000

0600-00019

S467FL-5-RMM-915S

Nearson

1/2 Wave Dipole

2 X 0600-00025

S467FL-5-RMM-915

Nearson

1/2 Wave Dipole

2

X

0600-00024

S467AH-915

Nearson

1/2 Wave Dipole

2 X 0600-00027

S467AH-915R

Nearson

1/2 Wave Dipole

2 X 0600-00028

S161AH-915R

Nearson

1/2 Wave Dipole

2.5 X 0600-00029

S161AH-915

Nearson

1/2 Wave Dipole

2.5 X 0600-00030

S331AH-915

Nearson

1/4 Wave Dipole

1

X

-

Y22831

Comtelco

Yagi

6 dBd

X

-

Y2283A-915-10RP

Comtelco

Yagi

6 dBd

X

-

SG101N9151

Nearson

Omni 5 X

-

SG101NT-915

Nearson

Omni 5 X

HARDWARE

Mechanical Drawing

Figure 7: Mechanical Drawing

Approved Antenna List

Table 5: CL4790 approved antennas

1.

Strictly requires professional installation

Note: You may use different antenna manufacturers as long as the antenna is of like type and equal or

lesser gain to one of the antennas listed in the table above.

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RELATED DOCUMENTS AND FILES

The following additional CL4790 technical documents are also available from the Laird RAMP ConnexLink
modules product page under the Documentation tab:

 Product Brief
 CL4790 User Guide

The following downloads are also available from the Laird RAMP ISM modules product page:

 Configuration Utility
 USB Drivers