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MHX-900 Operating Manual: Chapter 1 Introduction

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twenty different user-selectable pseudo-random hopping
patterns to offer the possibility of separately operating multiple
networks while providing security, reliability and high tolerance
to interference;

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encryption key with 65536 user-selectable values to maximize
security and privacy of communications;

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built-in CRC-16 error detection and auto re-transmit to provide
100% accuracy and reliability of data;

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ease of installation and use – the MHX-900 module uses a
subset of standard AT style commands making it compatible
with most communication packages, such as HyperTerminal.

While the typical application for the MHX-900 is to provide a mid- to long-
range wireless communications link between DTEs, it can be adapted to
almost any situation where an asynchronous serial interface is used and data
intercommunication is required.

1.2  About this Manual

This manual has been provided as a guide and reference for installing and
using MHX-900 wireless modem modules.  The manual contains instructions,
suggestions, and information which will help you set up and achieve optimal
performance from your equipment using the MHX-900 module.

It is assumed that users of the MHX-900 module have either system
integration or system design experience.  Chapter 2 details the requirements
and connections of the MHX-900 module.  Chapter 3 describes the AT
command register setup and configuration.  The Appendices, including the
Glossary of Terms, are provided as informational references which you may
find useful throughout the use of this manual as well as during the operation
of the wireless modem.

Throughout the manual, you will encounter not only illustrations that further
elaborate on the accompanying text, but also several symbols which you
should be attentive to:

Caution or Warning:

 Usually advises against some action which could

result in undesired or detrimental consequences.

Point to Remember:

 Highlights a key feature, point, or step which is worth

noting,  Keeping these in mind will make using the MHX-900 more useful
or easier to use.

Tip:

 An idea or suggestion is provided to improve efficiency or to make

something more useful.

With that in mind, enjoy extending the boundaries of your communications
with the MHX-900 module.

Содержание MHX-900

Страница 1: ...mplete However the company reserves the right to make changes or enhancements to the manual and or the product described herein at any time and without notice Furthermore Microhard Systems Inc assumes...

Страница 2: ......

Страница 3: ...ration 10 W Write Configuration to memory 10 Sxxx Read S register value 10 Sxxx yyy Set S register value 10 3 2 Command Result Codes 10 3 3 S Registers 11 S Register 2 Escape Code 11 S Register 3 CR C...

Страница 4: ......

Страница 5: ...ndability The MHX 900 module s versatility makes it the ideal solution for applications ranging from office productivity to industrial data control and acquisition While a pair of MHX 900 modules can...

Страница 6: ...ins instructions suggestions and information which will help you set up and achieve optimal performance from your equipment using the MHX 900 module It is assumed that users of the MHX 900 module have...

Страница 7: ...n new or existing designs n Relatively small footprint for the MHX 900 module e g 2 1 W x 3 5 L x 0 8 H on the OEM PCB n Serial port and control signals from the host microprocessor See sample applica...

Страница 8: ...MHX 900 module s digital electronics To simplify the OEM design the Radio VCC can be connected to the Logic VCC Maximum current while transmitting is approx 100 mA DC GND These are the Ground supply...

Страница 9: ...minimum configuration requirements for point to point and point to multipoint are summarized below These requirements will get you started and only ensure that a link can be established but do not ne...

Страница 10: ...iguration into non volatile memory and are therefore retained even after powering down Each item and the settable parameters within the modem configuration are described in detail in Chapter 3 Configu...

Страница 11: ...er command 3 Issuing the online command You can place the modem into Command Mode either by 1 Sending the escape sequence 2 Toggling the DTR line Note When the connection is lost to the remote modem t...

Страница 12: ...able commands denotes standard factory settings A Answer The A command causes the modem to attempt to connect with another remote modem D Dial Using the D command the modem will set itself for master...

Страница 13: ...d load stored configuration The Z command resets the modem and loads the stored configuration C DCD Data Carrier Detect The C command controls the modems DCD output signal to the host microprocessor T...

Страница 14: ...e modem s non volatile memory Sxxx Read S register value This command causes the modem to display the current setting of S register xxx Sxxx yyy Set S register value see section on S Registers This co...

Страница 15: ...43 S Register 3 CR Control Code This register contains the ASCII value of the carriage return character This is the character that is used to end the command line and is also the character that appear...

Страница 16: ...edgements along with CRC error checking ensure that data is passed through exactly once and that the data is not corrupted 3 Master Point to Multipoint In a point to multipoint network one unit should...

Страница 17: ...reliably at 115200 S Register 103 Wireless Link Rate The Wireless Link Rate is the speed and optimization method for which modems will communicate over the RF link The allowable settings are 1 Turbo...

Страница 18: ...rently in close proximity it is suggested that an atypical value be chosen perhaps something meaningful yet not easily selected by chance or coincidence Default is 0 S Register 105 Unit Address In poi...

Страница 19: ...f high gain directional antennas are placed high above ground level and are in direct line of sight 10 mW 200 500 ft indoors 8 15 km outdoors 100 mW 400 800 ft indoors 15 25 km outdoors 1000 mW 1 W Ty...

Страница 20: ...he following settings are available S Register 111 Minimum Size This setting has a range of 0 to 255 and defines the number of bytes to accumulate from the DTE before transmitting a packet Setting thi...

Страница 21: ...ximum Size 255 S113 Retransmissions 255 S114 Address Header Disabled S Register 111 Minimum Size The Minimum Size parameter prevents the Slave from sending data until it has buffered a minimum number...

Страница 22: ...Maximum Packet Size includes the Address Header For example if the Maximum Packet Size is set to 128 and the Text Address Header option is selected then the Master will tell the Slave to send a maxim...

Страница 23: ...mand mode V View Configuration W Write configuration to memory Sxx Read S register value Sxx yy Set S register value Result Codes 0 OK 1 CONNECT 2 RING 3 NO CARRIER 4 ERROR 8 NO ANSWER 10 CONNECT 2400...

Страница 24: ...20 MHX 900 Operating Manual Appendix A Modem Command Summary...

Страница 25: ...rted TTL low by the DTE to inform the modem that it is alive and ready for communications SG Signal Ground Provides a ground reference for all signals transmitted by both DTE and DCE DSR Data Set Read...

Страница 26: ...22 MHX 900 Operating Manual Appendix B Serial Interface...

Страница 27: ...Y RESULT On this implementation the onboard SCI of the PIC 16C74 is directly connected pins 22 and 23 of the MHX 900 The bi directional Port D is used for asserting or monitoring control signals from...

Страница 28: ...24 MHX 900 Operating Manual Appendix C Sample Schematic Diagram...

Страница 29: ...The same Hopping Interval S Register S109 value must be selected for both modems n The same Encryption Key S Register S107 value must be selected for both modems The master can now attempt to synchron...

Страница 30: ...26 MHX 900 Operating Manual Appendix D Modem Setup Overview...

Страница 31: ...stained in intelligent asymmetrical full duplex transmission mode Communications Range Up to 30 kilometres 19 miles line of sight Power Requirements 4 75 to 5 5 VDC Power Consumption 5500 mA at 1 W tr...

Страница 32: ...28 MHX 900 Operating Manual Appendix E Technical Specifications...

Страница 33: ...detection scheme for transmitted data Performed by using a polynomial algorithm on data and appending a checksum to the end of the packet At the receiving end a similar algorithm is performed and chec...

Страница 34: ...device RS 232 Recommended Standard 232 more accurately RS 232C or EIA TIA 232E Defined by the EIA a widely known standard electrical and physical interface for linking DCEs and DTEs for serial data co...

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