HORNER HE200WCM910 User manual


User Manual for
HE200WCM910
Wireless Communication
RS-232/485
RF Modem
27 June 2005 MAN0782-02

RS‐232/485RFModemProductManual–MAN0782‐02Pageiii
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PREFACE
This manual explains how to use the RS-232/485 RF Modem (HE200WCM910).
Copyright (C) 2005 Horner APG, LLC., 640 North Sherman Drive Indianapolis, Indiana 46201. All rights reserved.
No part of this publication may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated
into any language or computer language, in any form by any means, electronic, mechanical, magnetic, optical,
chemical, manual or otherwise, without the prior agreement and written permission of Horner APG, Inc.
Copyrights of part of this manual belong to MaxStream, Inc.
All software described in this document or media is also copyrighted material subject to the terms and conditions
of the Horner Software License Agreement.
Information in this document is subject to change without notice and does not represent a commitment on the
part of Horner APG.
SmartStack, SmartStix and CsCAN are trademarks of Horner APG.
Xtend is a registered trademark of MaxStream, Inc.
For user manual updates and assistance, contact Technical Support:
North America:
[phone]
www.heapg.com
Europe:
(+) 353-21-4321-266
www.horner-apg.com

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LIMITED WARRANTY AND LIMITATION OF LIABILITY
Horner APG,LLC. ("HE-APG") warrants to the original purchaser that the WCM910 module manufactured by HE-APG is free
from defects in material and workmanship under normal use and service. The obligation of HE-APG under this warranty shall
be limited to the repair or exchange of any part or parts which may prove defective under normal use and service within two
(2) years from the date of manufacture or eighteen (18) months from the date of installation by the original purchaser
whichever occurs first, such defect to be disclosed to the satisfaction of HE-APG after examination by HE-APG of the allegedly
defective part or parts. THIS WARRANTY IS EXPRESSLY IN LIEU OF ALL OTHER WARRANTIES EXPRESSED OR
IMPLIED INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR USE AND OF ALL OTHER
OBLIGATIONS OR LIABILITIES AND HE-APG NEITHER ASSUMES, NOR AUTHORIZES ANY OTHER PERSON TO
ASSUME FOR HE-APG, ANY OTHER LIABILITY IN CONNECTION WITH THE SALE OF THIS WCM910 module. THIS
WARRANTY SHALL NOT APPLY TO THIS WCM910 module OR ANY PART THEREOF WHICH HAS BEEN SUBJECT TO
ACCIDENT, NEGLIGENCE, ALTERATION, ABUSE, OR MISUSE. HE-APG MAKES NO WARRANTY WHATSOEVER IN
RESPECT TO ACCESSORIES OR PARTS NOT SUPPLIED BY HE-APG. THE TERM "ORIGINAL PURCHASER", AS USED
IN THIS WARRANTY, SHALL BE DEEMED TO MEAN THAT PERSON FOR WHOM THE WCM910 module IS ORIGINALLY
INSTALLED. THIS WARRANTY SHALL APPLY ONLY WITHIN THE BOUNDARIES OF THE CONTINENTAL UNITED
STATES.
In no event, whether as a result of breach of contract, warranty, tort (including negligence) or otherwise, shall HE-
APG or its suppliers be liable of any special, consequential, incidental or penal damages including, but not limited
to, loss of profit or revenues, loss of use of the products or any associated equipment, damage to associated
equipment, cost of capital, cost of substitute products, facilities, services or replacement power, down time costs,
or claims of original purchaser's customers for such damages.
To obtain warranty service, return the product to your distributor with a description of the problem, proof of
purchase, post paid, insured and in a suitable package.
ABOUT PROGRAMMING EXAMPLES
Any example programs and program segments in this manual or provided on accompanying diskettes are included
solely for illustrative purposes. Due to the many variables and requirements associated with any particular
installation, Horner APG cannot assume responsibility or liability for actual use based on the examples and
diagrams. It is the sole responsibility of the system designer utilizing the WCM910 module to appropriately design
the end system, to appropriately integrate the WCM910 module and to make safety provisions for the end
equipment as is usual and customary in industrial applications as defined in any codes or standards which apply.
Note: The programming examples shown in this manual are for illustrative
purposes only. Proper machine operation is the sole responsibility of the
system integrator.

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Contents
1. Horner RS-232/485 RF Modem 7
Features 7
Worldwide Acceptance 7
Specifications 8
RS-232/485 Interface 9
2. Interfacing Protocols 10
RS-232 Operation 10
DIP Switch Settings & Pin Signals 10
RS-485 (2-wire) Operation 13
DIP Switch Settings & Pin Signals 13
RS-485 (4-wire) & RS-422 Operation 14
DIP Switch Settings & Pin Signals 14
RS-485/422 Connection Guidelines 15
3. RF Operation 16
Serial Communications 16
RS-232 and RS-485/422 Data Flow 16
Host and RF Modem I/O Settings 16
Flow Control 17
Modes of Operation 18
Idle Mode 18
Transmit Mode 18
Receive Mode 20
Sleep Mode 21
Shutdown Mode 21
Command Mode 22
RF Communication Options 24
Addressing Options 24
Streaming Mode 25
Acknowledged Mode 26
Multi-Transmit Mode 28
4. Advanced Programming 29
Automatic DIP Switch Configurations 29
Programming the RS-232/485 RF Modem 30
AT Command Examples (RadioSet Software) 30
Binary Command Example 31
Command Descriptions (Short) 32
Command Descriptions (long) 33
Appendix A: Agency Certifications 51
FCC Certification 51
Labeling Requirements 51
FCC Notices 52
FCC-Approved Antennas (900 MHz) 53
IC (Industry Canada) Certification 55
Appendix B: Additional Information 56
Technical Support 56

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1.HornerRS‐232/485RFModem
Features
Long Range Performance
1 Watt Power Output (1 mW – 1 W, selectable)
Range (@ 9600 bps throughput data rate):
• Indoor/Urban: up to 3000’ (900 m)
• Outdoor line-of-sight:
up to 14 miles (22 km) w/ dipole antenna
• Outdoorline-of-sight:
up to 40 miles (64 km) w/ high gain antenna
Range (@ 115200 bps throughput data rate):
• Indoor/Urban: up to 1500’ (450 m)
• Outdoor line-of-sight:
up to 7 miles (11 km) w/ dipole antenna
• Outdoor line-of-sight:
up to 20 miles (32 km) w/ high gain antenna
Receiver Sensitivity: -110 dBm (@ 9600 baud),
–100 dBm (@ 115200 baud)
Advanced Networking & Security
True Peer-to-Peer (no “master” required),
Point-to-Point, Point-to-Multipoint & Multidrop
Retries and Acknowledgements
FHSS (Frequency Hopping Spread Spectrum)
10 hopping channels - each with over 65,000 network addresses available
256-bit AES Encryption (See KY Command [p39] for implementation)
Worldwide Acceptance
FCC Approved (USA - Go to Appendix A [p51] for FCC Requirements)
Systems that contain RS-232/485 RF Modems can inherit FCC Certification
IC Approved (Canada)
ISM (Industrial, Scientific & Medical) license-free 902-928 MHz frequency band
Manufactured under ISO 9001:2000 registered standards
Easy-to-Use
No configuration required
Advanced configurations available
through AT & binary Commands
External DIP Switch configurations
7 to 28 V power supply
Continuous RF data stream of up to
115.2 kbps
Transparent Operation – Wireless links
replace serial wires
Software-selectable serial interfacing
MODBUS, , , &
I/O Support
XII™ Interference Immunity
Power-saving Sleep Modes
Streaming, Acknowledged & Multi-Send
RF Communication Options
Free & Unlimited Technical Support
The RS-232/485 RF Modem (900 MHz) is our longest range drop-in
wireless solution. Out-of-box, the modem is equipped to sustain long
range wireless links between devices. Simply enter serial data into one
modem and the data surfaces on the other side of the wireless link.
The modem transfers a standard asynchronous serial data stream
between two or more modems. Its built-in RS-232, RS-485 and RS-422
interfacing allows for rapid integration into existing data systems.

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Specifications
Table1.1.RS‐232/485RFModemSpecifications(900MHz)
Performance @ 9600 bps Throughput Data Rate @ 115200 bps Throughput Data Rate
Transmit Power Output 1 mW - 1 W (software selectable) 1 mW - 1 W (software selectable)
Indoor/Urban Range Up to 3000’ (900 m) Up to 1500’ (450 m)
Outdoor
RF line-of-sight Range Up to 14 miles (22 km) w/ dipole antenna Up to 40 miles (64 km) w/ high-gain antenna Up to 7 miles (11 km) w/ dipole antenna Up to 20 miles (32 km) w/ high-gain antenna
Interface Data Rate
(selectable using BD Command) 1200 - 230400 bps 1200 - 230400 bps
RF Data Rate 10000 bps 125000 bps
Receiver Sensitivity -110 dBm -100 dBm
Power Requirements (refer also to Table1. 2)
Receive Current 110 mA 110 mA
16 sec cyclic sleep
(SM=8) 20 mA 19 mA
8 sec cyclic sleep
(SM=7) 21 mA 19 mA
4 sec cyclic sleep
(SM=6) 24 mA 20 mA
2 sec cyclic sleep
(SM=5) 30 mA 22 mA
Idle Currents
1 sec cyclic sleep
(SM=4) 39 mA 25 mA
Pin Sleep Power Down 17 mA 17 mA
Serial Port Sleep Power Down 45 mA 45 mA
General
Frequency 902-928 MHz ISM Band
Spread Spectrum FHSS (Frequency Hopping Spread Spectrum)
Modulation FSK (Frequency Shift Keying)
Supported Network Topologies Peer-to-Peer, Point-to-Point, Point-to-Multipoint & Multidrop
Channel Capacity 10 hop sequences share 50 frequencies
Physical Properties
Size 2.75” x 5.50” x 1.124” (7.90 cm x 13.90 cm x3.80 cm)
Weight 7.1 oz. (200 g)
Serial Connector DB-9
Operating Temperature -40 to 85º C (industrial)
Antenna
Connector RPSMA (Reverse-polarity SMA)
Type ½ wave dipole whip, 6.75” (17.1 cm), 2.1 dBi Gain
Impedance 50 ohms unbalanced
Certifications
FCC Part 15.247 OUR-9XTEND
Industry Canada (IC) 4214A-9XTEND
Table1.2.RFModemSpecifications–Relativetouser‐selectedTXPowerOutput
Power Requirements (TX Currents Relative To Each TX Power Output Option)
Transmit Power Output 1 mW 10 mW 100 mW 500 mW 1 W
Transmit Current @9600 baud
(9 VDC supply voltage, typical) 110 mA 145 mA 250 mA 510 mA 900 mA
Transmit Current @115K baud
(9 VDC supply voltage, typical) 110 mA 140 mA 245 mA 500 mA 800 mA

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RS-232/485 Interface
1.1a. Config (Configuration) Switch
Figure1.1.FrontView
1.1b. I/O LEDs
LEDs indicate modem activity as follows:
Yellow (top LED) = RX
Green (middle) = TX
Red (bottom) = Power/TX Indicator (Red light is on when
powered, pulses off briefly during RF transmission)
1.1c. Serial Port (DB-9)
Standard female DB-9 (RS-232) DCE connector – Connector can be
also used for RS-485 and RS-422 connections.
1.1d. RSSI LEDs
RSSI LEDs indicate the amount of fade margin present in an active
wireless link. Fade margin is the difference between the incoming
signal strength and the modem’s receiver sensitivity.
3 LEDs on = Very Strong Signal (> 30 dB fade margin)
2 LEDs on = Strong Signal (> 20 dB fade margin)
1 LED on = Moderate Signal (> 10 dB fade margin)
0 LED on = Weak Signal (< 10 dB fade margin)
1.1e. Power Connector *
7-28 VDC Power Connector (Center positive, 5.5/2.1mm)
1.2a. DIP Switch
Figure1.2.BackView
Refer to Automatic DIP Switch Configurations [p29] for more info.
1.2b. Antenna Port
Port is a 50ΩRF signal connector for connecting to an external
antenna. The connector type is RPSMA (Reverse Polarity SMA)
female. The connector has threads on the outside of a barrel and a
male center conductor.
Figure1.3.DIPSwitchSettings
The Configuration Switch provides an alternate method for
entering into Command Mode. To enter Command Mode at the
default RF data rate of the RF modem, depress the Config
Switch for two seconds.
During the power-on sequence, the DIP Switch automatically
configures the RS-232/485 RF Modem to operate in different
modes. Each time the RF modem is powered-on, intelligence inside
the RS-232/485 RF Modem programs the modem according to the
positions of the DIP Switch. [Refer to Figure 1.3 for DIP Switch
settings.]
2a.DIPSwitch
1.1b.I/OLEDs
1.1d.RSSILEDs
1.1c.SerialPort
1.1e.PowerConnector*
1.1a.Confi
g
Switch
*Note:TheRS‐232‐485RFModemcan
acceptvoltagesaslowas5(±5%)V.
ContactHornertechnicalsupportto
im
p
lementthiso
p
tion.
2b.AntennaPort

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2.InterfacingProtocols
The RS-232/485 RF Modem supports the following interfacing protocols:
• RS-232
• RS-485 (2-wire) Half-Duplex
• RS-485 (4-wire) and RS-422
RS-232 Operation
DIP Switch Settings & Pin Signals
Figure2.1.Figure2.2.    
RS‐232DIPSwitchSettingsPinsusedonthefemaleRS‐232(DB‐9)
 SerialConnector
DIPSwitchsettingsarereadandapplied
onlywhilepowering‐on.
Table2.1.RS‐232SignalsandtheirimplementationsontheRS‐232/485RFModem
(Low‐assertedsignalsaredistinguishedbyhorizontallineoverpinname.)
DB-9 Pin RS-232
Name Module Name* Description Implementation
1 DCD
GPO2 /
RX LED Data-Carrier-Detect Connected to DSR (pin6)
2 RXD DO Received Data Serial data exiting the RF Modem (to host)
3 TXD DI Transmitted Data Serial data entering into the RF modem (from host)
4 DTR GPI2 / SLEEP Data-Terminal-Ready Can enable POWER-DOWN on the RF Modem
5 GND - Ground Signal Ground
6 DSR
GPO2 /
RX LED Data-Set-Ready Connected to DCD (pin1)
7 / CMD GPI1 / /
CMD Request-to-Send Provides flow control or enables “Command Mode” on the RF Modem
8 GPO1 / /
RS-485 TX EN Clear-to-Send Provides flow control
9 RI - Ring Indicator
Optional power input that is connected internally to the
positive lead of the front power connector
*InsidetheRS‐232/485RFModemisanOEMRFModule.Thenamesinthiscolumnrefertothepinsignalsof
theembeddedmodule.RS‐232/485Commands[p32]usedtoconfigurepinbehaviorsarenamedaccordingto
thepinsofthemodule,nottheRS‐232connection.

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Wiring Diagram: RS-232 DTE Device to a DCE RF Modem
Figure2.3.RS‐232DTE(maleconnector)devicewiredtoanRS‐232/485RFModem(femaleconnector)















Wiring Diagram: DCE RF Modem to an RS-232 DCE Device
Figure2.4.RS‐232/485RFModem(femaleconnector)wiredtoanRS‐232DTE(maleconnector)device
Sample Wireless Connection: DTE ÙDCE DCE ÙDCE
Figure2.5.TypicalwirelessconnectionusedforserialcommunicationsbetweenDTEandDCEdevices


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RS-485 (2-wire) Operation
DIP Switch Settings & Pin Signals
Figure2.6.Figure2.7.    
RS‐485(2‐wire)Half‐DuplexPinsusedonthefemaleRS‐232(DB‐9)
DIPSwitchSettingsSerialConnector
Figure2.8.
RS‐485(2‐wire)withTermination(optional)




Terminationisthe120ΩresistorbetweenT+andT‐.
DIPSwitchsettingsarereadandappliedonlywhilepowering‐on.
Note: Refer to Figures 2.15 and 2.16 for RJ-45 connector pin designations used in
RS-485/422 environments.
Table2.2.RS‐485(2‐wirehalf‐duplex)SignalsandtheirimplementationsontheRS‐232/485RFModem
DB-9 Pin RS-485 Name Description Implementation
2 T/R- (TRA) Negative Data Line Transmit serial data to and from the
RS-232/485 RF Modem
5 GND Ground Signal Ground
8 T/R+ (TRB) Positive Data Line Transmit serial data to and from the
RS-232/485 RF Modem
9 PWR Power Optional power input that is connected internally
to the front power connector
1, 3, 4, 6, 7 not used
Wiring Diagram: RS-485 (2-wire) Half-Duplex
Figure2.9.RS‐232/485RFModeminanRS‐485(2‐wire)half‐duplexenvironment

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RS-485 (4-wire) & RS-422 Operation
DIP Switch Settings & Pin Signals
Figure2.10.Figure2.11.    
RS‐485(4‐wire)andRS‐422PinsusedonthefemaleRS‐232(DB‐9)
DIPSwitchSettingsSerialConnector

Figure2.12.
RS‐485(4‐wire)&RS‐422withTermination(optional)




Terminationisthe120ΩresistorbetweenT+andT‐.
DIPSwitchsettingsarereadandappliedonlywhilepowering‐on.

Table2.3.RS‐485/422(4‐wire)SignalsandtheirimplementationswiththeRS‐232/485RFModem
DB-9 Pin RS-485/422
Name Description Implementation
2 T- (TA)
Transmit Negative
Data Line Serial data sent from the RS-232/485 RF Modem
3 R- (RA)
Receive Negative
Data Line Serial data received by the RS-232/485 RF Modem
5 GND Signal Ground Ground
7 R+ (RB)
Receive Positive
Data Line Serial data received by the RS-232/485 RF Modem
8 T+ (TB)
Transmit Positive
Data Line Serial data sent from the RS-232/485 RF Modem
9 PWR Power Optional power input that is connected internally
to the front power connector
1, 4, 6 not used
Wiring Diagram: RS-485 (4-wire) Half-Duplex
Figure2.13.RS‐232/485RFModeminanRS‐485(4‐wire)environment

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Wiring Diagram: RS-422
Figure2.14.RS‐232/485RFModeminanRS‐485(4‐wire)environment
RS-485/422 Connection Guidelines
The RS-485/422 protocol provides a solution for wired communications that can tolerate high
noise and push signals over long cable lengths. RS-485/422 signals can communicate as far as
4000 feet (1200 m). RS-232 signals are suitable for cable distances up to 100 feet (30.5 m).
RS-485 offers multi-drop capability in which up to 32 nodes can be connected. The RS-422
protocol is used for point-to-point communications.
Suggestions for integrating the RS-232/485 Modem with the RS-485/422 protocol:
1. When using Ethernet twisted pair cabling: Select wires so that T+ and T- are connected to
each wire in a twisted pair. Likewise, select wires so that R+ and R- are connected to a
twisted pair. (For example, tie the green and white/green wires to T+ and T-.)
2. For straight-through Ethernet cable (not cross-over cable) – The following wiring pattern
works well: Pin3 to T+, Pin4 to R+, Pin5 to R-, Pin6 to T-
3. Note that the connecting cable only requires 4 wires (even though there are 8 wires).
4. When using phone cabling (RJ-11) – Pin2 in the cable maps to Pin3 on opposite end of cable
and Pin1 maps to Pin4 respectively.
Figure2.15.MaleDB‐9toRJ‐45Adapter(yellow)
Figure2.16.FemaleDB‐9toRJ‐45Adapter(green)

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3.RFOperation
WARNING: When operating at 1 Watt power output, observe a minimum separation distance of 2’ (0.6 m) between modems.
Transmitting in close proximity of other modems can damage modem front ends.
Serial Communications
RS-232 and RS-485/422 Data Flow
The RS-232/485 RF Modem interfaces to a host device through a standard RS-232 (DB-9)
connector. Devices that have a standard RS-232 serial port can connect directly through the pins
of the RS-232/485 RF Modem as shown in the figure below.
Figure3.1.SystemDataFlowinanRS‐232environment
Host and RF Modem I/O Settings
Serial communications between a host and the RS-232/485 RF Modem are dependent upon
having matching baud rate, parity, stop bit & number of data bits settings. Refer to the table
below to ensure host serial port settings match those of the RS-232/485 RF Modem.
Table3.1.ParametervaluescriticaltoserialcommunicationsbetweentheRFModemandhost
Parameter Setting RS-232/485 RF Modem Default Parameter Value
Baud (Serial Data Rate) 9600 bps (BR parameter = 3)
Number of Data Bits 8 (NB parameter = 0)
Parity None (NB parameter = 0)
Number of Stop Bits 1 (NB parameter = 0)
Both the RF Modem and host (PC) settings can be viewed and adjusted using Horner’s
proprietary RadioSet Software. Use the “Terminal” or “Modem Configuration” tabs to configure
the RF Modem settings. Use the “PC Settings” tab to configure host settings. Refer to the
Advanced Programming and RadioSet Software sections for more information.

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Flow Control
Figure3.2.InternalDataFlowDiagram


DI (Data In) Buffer and Flow Control
When serial data enters the RS-232/485 Modem through the DI Pin, the data is stored in the DI
Buffer until it can be transmitted.
When the RB and RO parameter thresholds are satisfied (refer to Transmit Mode section [p18] for
more information), the modem attempts to initialize an RF connection. If the modem is already
receiving RF data, the serial data is stored in the modem’s DI Buffer. The DI buffer stores at least
2.1 KB. If the DI buffer becomes full, hardware or software flow control must be implemented in
order to prevent overflow (loss of data between the host and RS-232/485 Modem).
How to eliminate the need for flow control:
1. Send messages that are smaller than the DI buffer size. The size of the DI buffer varies
according to the packet size (PK parameter) and the parity setting (NB parameter) used.
2. Interface at a lower baud rate (BD parameter) than the RF data rate (BR parameter).
Two cases in which the DI Buffer may become full and possibly overflow:
1. If the serial interface data rate is set higher than the RF data rate of the modem, the modem
will receive data from the host faster than it can transmit the data over-the-air.
2. If the modem is receiving a continuous stream of RF data or if the modem is monitoring data
on a network, any serial data that arrives on the DI pin is placed in the DI Buffer. The data in
the DI buffer will be transmitted over-the-air when the modem no longer detects RF data in
the network.
Hardware Flow Control ( ). When the DI buffer is 17 bytes away from being full; by
default, the modem de-asserts (high) to signal to the host device to stop sending data [refer
to FT (Flow Control Threshold, p38) and CS (GPO1 Configuration, p36) Commands.]. is re-
asserted after the DI Buffer has 34 bytes of memory available.
Software Flow Control (XON). XON/XOFF software flow control can be enabled using the FL
(Software Flow Control) Command [p37]. This option only works with ASCII data.
DO (Data Out) Buffer & Flow Control
When RF data is received, the data enters the DO buffer and is sent out the serial port to a host
device. Once the DO Buffer reaches capacity, any additional incoming RF data is lost. The DO
buffer stores at least 2.1 KB.
Two cases in which the DO Buffer may become full and possibly overflow:
1. If the RF data rate is set higher than the interface data rate of the modem, the modem will
receive data from the transmitting modem faster than it can send the data to the host.
2. If the host does not allow the modem to transmit data out from the DO buffer because of
being held off by hardware or software flow control.
Hardware Flow Control ( ). If is enabled for flow control (RT Parameter = 2, p45), data
will not be sent out the DO Buffer as long as is de-asserted.
Software Flow Control (XOFF). XON/XOFF software flow control can be enabled using the FL
(Software Flow Control) Command [p37]. This option only works with ASCII data.

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Modes of Operation
RS-232/485 RF Modems operate in five modes.
Figure3.3.ModesofOperation
TheRFmodemcanonlybeinonemodeatatime.
Idle Mode
When not receiving or transmitting data, the modem is in Idle Mode. The modem uses the same
amount of power in Idle Mode as it does in Receive Mode.
The modem shifts into the other modes of operation under the following conditions:
• Serial data is received in the DI Buffer (Transmit Mode)
• Valid RF data is received through the antenna (Receive Mode)
• Command Mode Sequence is issued (Command Mode)
• Sleep Mode condition is met (Sleep Mode)
The modem automatically transitions to Idle Mode after finished responding to these conditions.
Transmit Mode
When the first byte of serial data is received from the host in the DI buffer, the modem attempts
to shift to Transmit Mode and initiate an RF connection with other modems. After transmission is
finished, the modem returns to Idle Mode.
RF transmission begins after either of the following criteria is met:
1. RB bytes have been received by the host and are pending for RF transmission.
[RB (Packetization Threshold) Command]
2. At least one character has been received by the host and is pending for RF transmission, and
RO character times of silence have been observed on the host.
[RO (Packetization Timeout) Command]
Figure3.4.TransmitModeDataFlow
The character timeout trigger can
be disabled by setting RO to zero.
In this case, transmission will not
begin until RB bytes have been
received and are pending for RF
transmission. The RB parameter
may be set to any value between 1
and the RF packet size (PK),
inclusive. Note that transition to
Transmit Mode cannot take place
during RF reception; the RF
reception must complete before
the modem can transition into
Transmit Mode.

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After either of the RB and RO conditions are met, the modem then initializes a communications
channel. Serial data in the DI buffer is grouped into RF packets (up to 2048 bytes in each packet
- refer to PK (Maximum RF Packet Size) Command), converted to RF data and then is transmitted
over-the-air until the DI buffer is empty.
Channel initialization is the process of sending an RF initializer that synchronizes receiving
modems with the transmitting modem. During channel initialization, incoming serial data
accumulates in the DI buffer.
RF data, which includes the payload data, follows the RF initializer. The payload includes up to
the maximum packet size (PK Command) bytes. As the TX modem nears the end of the
transmission, it inspects the DI buffer to see if more data exists to be transmitted. This could be
the case if more than PK bytes were originally pending in the DI buffer or if more bytes arrived
from the host during transmission. If more data is pending, the transmitting modem instructs all
listening modems that a subsequent packet is coming. Receiving modems move to the new
frequency and listen for the subsequent packet.
Refer to the RF Communication Options [p24] section for information and state diagrams that
illustrate channel initialization and the sequence of events that follow.
RF Packet
Figure3.5.RFPacketComponents
* When streaming multiple RF packets, the RF Initializer is only sent in front of the first packet.
RF Initializer
An RF initializer is sent each time a new connection sequence begins. The RF initializer contains
channel information that notifies receiving modems of information such as the hopping pattern
used by the transmitting modem. Channel initialization takes 5 ms at the 115k RF data rate and
54 ms at the 9600 RF data rate. The first transmission always sends an RF initializer.
An RF initializer can be of various lengths depending on the amount of time determined to be
required to prepare a receiving modem. For example, a wake-up initializer is a type of RF
initializer used to wake remote modems from Sleep Mode (Refer to the FH, LH, HT and SM
Commands for more information). The length of the wake-up initializer should be longer than the
length of time remote modems are in cyclic sleep.
Header
The header contains network addressing information that filters incoming RF data. The receiving
modem checks for matching a VID, Hopping Channel and Destination Address. Data that does not
pass through all three network security layers is discarded.
Figure3.6.NetworkLayersContainedintheHeader

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CRC (Cyclic Redundancy Check)
To verify data integrity and provide built-in error checking, a 16-bit CRC (Cyclic Redundancy
Check) is computed for the transmitted data and attached to the end of each RF packet before
transmission. On the receiving end, the receiving modem computes the CRC on all incoming RF
data. Received data that has an invalid CRC is discarded. [See Receive Mode section, next
section.]
Receive Mode
If a modem detects RF data while in Idle Mode, the modem transitions into Receive Mode to start
receiving RF packets. Once a packet is received, it goes through the receiving end of a CRC
(cyclic redundancy check) to ensure that the data was transmitted without error. If the CRC data
bits on the incoming packet are invalid, the packet is discarded. If the CRC is valid, the packet is
placed the DO Buffer.
Figure3.7.ReceiveModeDataFlow
*RefertotheAddressingOptionssection(undertheRFCommunicationOptionschapter)formore
informationaboutaddressrecognition.

The modem returns to Idle Mode after valid RF data is no longer detected or after an error is
detected within the received RF data. If serial data is stored in the DI buffer while the modem is
in Receive Mode, the serial data will be transmitted after the modem is finished receiving data
and returns to Idle Mode.

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Sleep Mode
Software Sleep
Sleep Modes enable the RS-232/485 Modem to operate at minimal power consumption when not
in use. Three Sleep Mode options are available:
• Host Controlled (Pin Sleep)
• Wake on Serial Port activity (Serial Port Sleep)
• Wake on RF activity (Cyclic Sleep)
For the modem to transition into Sleep Mode, SM (Sleep Mode) Parameter must have a non-zero
value and one of the following must occur:
1. The modem is idle (no data transmission or reception) for a user-defined period of time [See
ST (Time before Sleep) Command]
[OR]
2. GPI2 pin is asserted [GPI2 is equivalent to DTR (Data-Terminal-Ready) under RS-232
operation. Refer to the RS-232 Operation [p10] section for more information.]
While in Sleep Mode, the modem will not transmit or receive data until the modem first shifts
back to Idle Mode. The return to Idle Mode is triggered by the de-assertion of GPI2 or the arrival
of a serial byte through the DI pin. Sleep Mode is enabled and disabled using SM Command.
Table3.2.SummaryofSleepModeConfigurations
Sleep Mode
Setting Transition into Sleep Mode Transition out of Sleep Mode Related Commands Power Consumption
Pin Sleep
(SM=1)
Host can shut down and
wake modems.
Assert GPI2 (SLEEP) pin.
De-Assert GPI2 (SLEEP)
pin. SM Typically 17 mA
Serial Port Sleep
(SM=2)
Automatic transition into
Sleep Mode after user-
defined period of inactivity
(no transmitting or
receiving). Period of
inactivity set using ST
Command.
When serial byte is received
on the DI pin. SM, ST Typically 45 mA
Cyclic Sleep
(SM=4-8)
Transitions into and out of Sleep Mode in cycles (user-
selectable wake-up interval of time set by SM Command).
The Cyclic Sleep interval time must be shorter than “Wake-
up Initializer Timer” (set by LH Command).
(Can be forced into Idle Mode using GPI2 (SLEEP) pin if
PW (Pin Wake-up) Command is issued.)
HT, LH, PW, SM, ST Typically 25 mA (when sleeping, SM=4 ,
1 sec, @120K baud)

FormoreinformationaboutSleepModes,refertotheindividualcommandslistedin“RelatedCommands”
columnofthetable.SMCommandisthebeststartingpoint.
Shutdown Mode
Hardware Sleep
Shutdown Mode offers the lowest power mode available to Horner modem users (< 1 µA). This
mode is not supported by the stand-alone RS-232/485 RF Modem, but is available through the
OEM RF Module that is mounted inside the stand-alone RS-232/485 RF Modem.
Contact Horner Technical Support for more information.