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Operating Manual
900 MHz Wireless
Spread-Spectrum OEM Modem
Revision 03 - May 12, 1999
Microhard Systems Inc. has made every effort to assure that this document is accurate and complete. 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 no liability resulting from any omissions
in this document, or out of the application or use of the device described herein.
Microhard Systems Inc.
Leaders in Wireless Telecom
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Table of Contents
Related Manuals for Microhard Systems MHX-900
Summary of Contents for Microhard Systems MHX-900
- Page 1 Revision 03 - May 12, 1999 Microhard Systems Inc. has made every effort to assure that this document is accurate and complete. 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.
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Page 3: Table Of Contents
S Registers 111 to 115 - Packet Parameters - Point to Multipoint Mode..............17 Appendices Modem Command Summary ..........................19 Serial Interface..............................21 Sample Schematic Diagram ..........................23 Modem Setup Overview ............................ 25 Technical Specifications ............................ 27 Glossary ................................29 MHX-900 Operating Manual: Contents... -
Page 5: Introduction
While the MHX-900 module is compact in its design, it delivers power and convenience and offers quality and dependability. The MHX-900 module’ s versatility makes it the ideal solution for applications ranging from office- productivity to industrial data control and acquisition. -
Page 6: About This Manual
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. -
Page 7: Initial Setup And Configuration
MHX-900 Wireless Modem module Operating Manual (this document) 2.1 Additional Requirements Since the MHX-900 module is a unique product in a class of its own, it will communicate only with another MHX-900 module which has been compatibly configured. Thus, at least two MHX-900 modules will be required to establish a wireless communications link. - Page 8 The interface connectors and indicator lights are summarized below: For maximum power, use separate power supplies for Vcc Radio - These connections supply power for the MHX-900 module’ s radio the radio and the digital electronics. deck electronics. For 1 watt maximum output, the required supply rating should be 5.25 VDC +- 5%.
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Page 9: Configuration
2.3 Configuration Prior to establishing a wireless link, each MHX-900 module that will participate in the link must be correctly configured for compatibility and for the desired mode of operation. The two most common types of networks used are: n Point-to-point: A Master station communicates with a single Slave station. -
Page 10: Checking The Link
MHX-900 module could result in It is recommended that if MHX-900 modules will be deployed in a field undesired performance, and may where large distances separate the units, the modems should be configured damage the unit. -
Page 11: Configuration Options
3. Configuration Options 3.0 Command Line Interface The MHX-900 modem module is easily configured to meet a wide range of needs and applications. You can have your modem perform a variety of functions by sending it instructions (in the form of commands). Sending a command overrides the modem’... -
Page 12: At Commands
Typically, the ‘ +’ character is used as the escape code. preceded and followed by 1 second of inactivity 3.1 AT Commands Several AT Commands are supported by the MHX-900 module. The following is a short description of all available commands. ‘ *’ denotes standard factory settings. -
Page 13: Q - Quiet Mode
The &F command resets the modem and loads the default factory configuration. &K Handshaking The &K command controls the handshaking between the modem and host microprocessor. &K0 Disable handshaking *&K3 Enable hardware handshaking (RTS/CTS) MHX-900 Operating Manual: Chapter 3 Configuration Options... -
Page 14: Sdsr (Data Set Ready)
This command sets the specified S register to a value specified by yyy. 3.2 Command Result Codes The MHX-900 module can either display the results of a command as either text strings or numerical data. The following chart shows resulting text string and corresponding numeric result. -
Page 15: S Registers
Register S5 sets the ASCII value of the backspace character. This character is both the character created by entering BACKSPACE and the character echoed to move the cursor to the left. Default is ‘ BS’ (decimal 8). MHX-900 Operating Manual: Chapter 3 Configuration Options... -
Page 16: S Register 101 - Operating Mode
S Register 101 - Operating Mode The Operating Mode (register S101) partly defines the “personality” of the MHX-900 module. Allowable settings for this register are 1 through 4. Default is 2 (Slave point to point). Each unit should be configured as a Master or Slave. The user should... -
Page 17: S Register 102 - Serial Baud Rate
If DTEs require nearly 115.2 kbps of sustained bandwidth, then the wireless rate should be set to Turbo (setting it lower would “bottleneck” data transmissions in the wireless link). Note that there is a compromise between speed, performance and range. MHX-900 Operating Manual: Chapter 3 Configuration Options... -
Page 18: S Register 104 - Network Address
Default is 1. to 65535. S Register 106 - Hopping Pattern Since the MHX-900 is a frequency-hopping modem, the carrier frequency changes periodically according to one of twenty pseudo-random patterns, Ensure that all units within a selected by defining the Hopping Pattern. -
Page 19: S Register 108 - Output Power Level
S Register 108 - Output Power Level The Output Power Level determines at what power the MHX-900 transmits. The super-sensitive MHX-900 can operate with very low power levels, so it is recommended that the lowest power necessary is used; using excessive power contributes to unnecessary “RF pollution”. -
Page 20: S Register 109 - Hopping Interval
Since a smaller packet size results in a proportionally higher overhead and lower overall throughput on a good connection, this should only be reduced if many errors are being detected by CRC (see Radio Statistics option of configuration). MHX-900 Operating Manual: Chapter 3 Configuration Options... -
Page 21: S Registers 111 To 115 - Packet Parameters - Point To Multipoint Mode
Similar to the Retry Limit in Point-to-Point, the Slaves in a multipoint system will reattempt to send a packet of data until it receives an acknowledge or until it reaches the Retry Limit. MHX-900 Operating Manual: Chapter 3 Configuration Options... - Page 22 The Slave will transmit more frequently when a Repeat Interval with a smaller range is selected. Choose 1) for the most frequent repeats and choose 8) for the least frequent repeats. MHX-900 Operating Manual: Chapter 3 Configuration Options...
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Page 23: Appendices A. Modem Command Summary
A. Modem Command Summary The following provides a command summary for the MHX-900 module. Factory settings are denoted with a ‘ *’ . AT Commands Result Codes Answer Dial CONNECT Command Echo RING E0 No Echo NO CARRIER * E1 Command Echo... - Page 24 MHX-900 Operating Manual: Appendix A Modem Command Summary...
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Page 25: Serial Interface
B. Serial Interface The MHX-900 module uses 8 pins on the 40 pin connector for asynchronous serial I/O. The interface conforms to TTL level RS-232 signals (ie. without level shifting), so direct connection to a host microprocessor is possible. The signals in the asynchronous serial interface are described below:... - Page 26 MHX-900 Operating Manual: Appendix B Serial Interface...
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Page 27: Sample Schematic Diagram
DO NOT CONNECT THE MHX-900 TO RS 232 DRIVER OUTPUTS. DAMAGE TO THE UNIT MAY 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 the MHX-900. - Page 28 MHX-900 Operating Manual: Appendix C Sample Schematic Diagram...
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Page 29: Modem Setup Overview
D. Modem Setup Overview The required commands required to setup an MHX-900 module 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 necessarily provide the best performance. - Page 30 MHX-900 Operating Manual: Appendix D Modem Setup Overview...
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Page 31: Technical Specifications
CRC-16 with auto re-transmit Encl: 2.1” x 3.5” x 0.75” (53 mm x 89 mm x 19 mm) Dimensions (WxDxH) Weight 75 grams Operating Environment Temperature: -40 to +65°C Humidity: 5 to 95%, non-condensing MHX-900 Operating Manual: Appendix E Technical Specifications... - Page 32 MHX-900 Operating Manual: Appendix E Technical Specifications...
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Page 33: Glossary
F. Glossary Terminology Used in the MHX-900 Operating Manual Asynchronous communications receiving end, a similar algorithm is performed A method of and checked against the transmitted checksum. telecommunications in which units of single bytes of data are sent separately and at an arbitrary time... - Page 34 (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 communications. Traditionally specifies a 25-pin D-sub connector, although MHX-900 Operating Manual: Appendix F Glossary...
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