Embedded Communications Systems RMX232, User Manual

Page 1: ...RMX232 Radio Modem User s Guide N11391 Embedded Communications Systems Specialists in Embedded RF Data Communications Monitoring and Control Systems ...

Page 2: ...the manual These radio devices may be subject to radio interference and may not function as intended if interference is present Systems should be designed to tolerate such interference RF transmission power levels are subject to regulatory approval in countries consequently it is possible that some radio modem functionality is not provided in your country Radio and EMC Regulations The user of RMX2...

Page 3: ...and Format 3 1 Configuration Commands in Detail 3 2 Chapter 4 Modem Operation Explained 4 1 Flow Control 4 1 Serial Port Flow Control 4 1 XON XOFF Flow Control Software 4 2 RTS CTS Flow Control Hardware 4 2 No Flow Control 4 2 Radio Modem Port Flow Control 4 2 Radio Modem Addressing Scheme 4 3 On Air Data Speed 4 4 DTR Power Control 4 5 Operating Modes 4 5 Acknowledged Point to Point 4 5 Acknowled...

Page 4: ...ce 5 3 Three Wire Half Duplex Interface 5 3 Connecting to other DTE and DCE Equipment 5 4 Chapter 6 Specifications 6 1 Chapter 7 Product Version Information 7 1 Version Information 7 1 Firmware Version Numbering Scheme 7 1 Chapter 8 Modification History 8 1 Bug Fixes Change History 8 1 User s Guide Page iii ...

Page 5: ...sed in a variety of data communications applications that require a simple to use invisible data link The radio modem is designed to interface to a variety of host devices These devices include computers PDA s personal organisers PLC s data loggers SCADA devices and intelligent control transducer systems The serial data transferred over the radio link is not altered the output serial data stream i...

Page 6: ... Multipoint RF networks Acknowledged MultiMaster mode Broadcast Multidrop mode User selectable serial DTE speeds 600 to 115200bps Serial protocol format is 8 data 1 stop no parity Selectable flow control of hardware software none On air data encryption error checking and data acknowledgements Low operating current Auto standby mode Configurable as a network repeater for extended range Built in con...

Page 7: ...lowing rates 600 1200 2400 4800 9600 14400 38400 57600 and 115200 When operating the radio modem at a DTE baud rate greater than the configured on air data throughput data received by the radio modem will be buffered internally At the higher DTE baud rates either hardware or software flow control should be used to prevent receive buffer overflows in the radio modem Connecting for the First Time Fo...

Page 8: ...r use Default operating mode for the RMX232 is in point to point mode If you require different interface settings to the factory set defaults you will need to refer to the later chapter covering the radio modem configuration commands Powering up the Radio Modems Once power is applied to the DC Jack on the bottom of the RMX232 you should see a welcome message appear on the communications applicatio...

Page 9: ...EDs are used to give the radio modem operator an indication of the current state of operation of the Radio Modem Indicator State Meaning RX TX Red Radio transmitting RX TX Green steady Link established and listening for data RX TX Green flash Radio in standby mode waiting to establish a link RX Data Red Radio receiving data Status Single pulsing Radio Modem is active but no link is established Sta...

Page 10: ... above your head in order to reduce potential shielding of the radio signal A few centimetres difference in the location of the radio modem can sometimes depending on surrounding furniture walls and equipment make all the difference between a reliable link and a link that is prone to constant errors and lost packets Potential RF Interference The radio modem is a sensitive piece of electronic equip...

Page 11: ...functions built in to the Radio Modem The diagnostic functions are explained in detail later If an installed system exhibits poor performance both the radio path and possible interference sources should be checked Again the diagnostic functions ping and radar can be used to check for these conditions A high failure rate reported by the radar test may indicate either the presence of interference or...

Page 12: ...ted both before and after and escape sequence is entered This pause prevents the radio modem from interpreting the escape sequence as data The guard time must also be met when the Radio Modem is initially powered up Configuration changes are stored permanently in non volatile memory within the Radio Modem Exiting Configuration Mode and returning back to data transfer mode is accomplished by typing...

Page 13: ...nd displays a list of the current radio modem user configured settings default Load factory settings This command loads the configuration stored and programmed at the factory This operation replaces all of the configuration options with factory default values The list below shows the factory default values which are written to non volatile memory using the default command baud 9600 airspd 9600 240...

Page 14: ... collisions and packet retries thus improving the overall network interoperability Command format airspd n where n 600 1200 2400 Applies to RMX232 151 173 600 1200 2400 4800 9600 unit Radio Modem unit address This command sets the device unit address To permit two radio modems to communicate they must have the same unit address and site code Multiple modem pairs can operate within close proximity ...

Page 15: ...stination radio modem As each packet is retransmitted by a repeater the packet count is decremented by one until the packet reaches a hop count of zero A repeater upon receiving a packet with a hop count of zero will immediately discard the packet This prevents a data packet from bouncing around a network forever A radio modem will not accept a data packet if it s hop count is anything but zero If...

Page 16: ...Command format addr n h where n 0 127 The unit number and site code specified as a single number in the range specified This parameter is not optional and must be given The value can be used as a single value thus addressing up to 128 remote units This effectively combines the unit number and site code Refer to section where h 0 3 This optional parameter sets the number of repeater hops to reach t...

Page 17: ...bles monitoring of the battery voltage level When battery monitoring is enabled if the battery level falls below a threshold of approximately 5 75 volts the modem status indicator will begin to flash slowly with a 1 second duty cycle Regardless of whether battery monitoring is on or off if the battery voltage drops to below 5 0V the radio modem will enter a reset state and cease to function until ...

Page 18: ... s return acknowledgement may not have been received In this instance after a time out period the packet is retransmitted The packet is retransmitted until either the appropriate acknowledgement is received or the packet retry count is exceeded If the packet retry count is exceeded the data in the radio modem is discarded and the radio modem re enters the standby mode Further data sent to the radi...

Page 19: ...on message at power up This command enables or disables the sign on message displayed when the radio modem powers up It s main use is to indicate the radio modem is working especially when it s being connected and used for the very first time It serves no other purpose and should therefore be disabled after the radio modem has been configured The welcome message when entering the configurator is a...

Page 20: ...ting from the remote unit will be returned and displayed After a setting has been updated on a remote unit the remote unit will execute a soft reset in order to bring that change into effect Note it is possible for an acknowledgement of a remote unit configuration change to be lost due to data collisions etc Therefore it is always advisable to interrogate the setting on the remote unit after an un...

Page 21: ...twork mode This mode of operation requires the use of intelligent host devices that perform network layer functions for data packet addressing routing and error control slave Sets a remote modem to be a slave device in a point to multipoint configuration A radio modem set to this mode is operationally identical to setting ptpmode to on The only difference is that in this mode a remote slave radio ...

Page 22: ...s it possible to run parity at one end and no parity at the other end of the link ping Ping test Please refer to chapter 4 for an overview of the ping function Command format ping n where n 0 15 Optional unit number to ping If not specified the current unit number is used The site address used corresponds to the value set using the site command radar Radar test Please refer to chapter 4 for an ove...

Page 23: ... capacity and that transmission is resumed when the receiving buffers have room This is the flow control function The radio modem has two kinds of flow control Serial port flow control Modem port flow control Computer DTE Radio Modem DCE Receive Transmit Buffer Buffer Radio Interface Serial port flow control DTE DCE Modem port flow control modem modem Two kinds of radio modem flow control Serial p...

Page 24: ...adio modem serial data is lost and the data transfer becomes corrupted When operating with flow control disabled the user must be aware of the maximum internal buffer size of 96 bytes in the radio modem The user must also be aware of the on air transfer rate between a pair of communicating radio modems Radio interference and other radio modem pairs operating within close proximity can affect the o...

Page 25: ... logical isolation for groups of up to 16 radio modem pairs plus repeaters This is useful when a number of operating sites in close proximity may use radio modem pairs and repeaters but need to remain logically separate A repeater will repeat only data packets matching its own site code and reject all others Therefore a single repeater can be used to extend the operating range of up to 16 point to...

Page 26: ...pected as radio is a shared medium Selecting the right on air data speed is dependant on a number of factors Some factors to consider include the amount of data each point to point link in the network is expected to transfer the rate of transfer that must be sustained over each point to point link and the total number of point to point links competing for air time within close proximity It is stro...

Page 27: ...ort that does not have DTR connected it will not be possible to wake up or use the radio modem In this instance DTR power control must be disabled Operating Modes The radio modem supports five modes of operation The first being the default mode point to point is a fully controlled data transfer mode using packet acknowledgements and retries to guaranteed delivery and reliability of data The second...

Page 28: ...dem receives a data packet the address and site code are checked if a match occurs the packet data is further processed A received data packet is discarded if there is no match with the unit address and site code Type hop seq Unit site code Data Bytes Checksum Data packet ready for transmission Before valid received data is sent to the attached host device via the serial port the Radio Modem will ...

Page 29: ...order for the modem to address a slave modem the connected host device must enter the configurator using the sequence then issue the addr command with appropriate parameters followed by a carriage return A period symbol is returned as confirmation that the parameters have been assigned to the appropriate RAM based unit address site code and or hop count The modem is then ready for connection and t...

Page 30: ... data The site code and unit address is still used by the radio modem when working in broadcast multidrop mode For a given multipoint network all radio modems within a group must contain the same site code and unit address MultiMaster Mode This mode of operation is determined by the configuration command keyword ptpmode being set to mmaster This mode of operation enables multiple remote modems wit...

Page 31: ...hop counts for traversing the repeater Each data packet contains a 2 bit field called the hop count Upon a packet being transmitted from a radio modem the hop count field is set with the units hop count setting The hop count field is decremented every time a network repeater retransmits the packet Upon this hop count reaching zero a repeater will not retransmit the packet thus preventing it from b...

Page 32: ...t is powered up and listening the remote modem s details are displayed to the user The details reported to the user from the remote unit include the baud rate setting the serial number the number of repeater hops taken and the time taken for each reply Assuming that another radio modem pair are operating within radio range and using the same unit address and site code the results from the ping req...

Page 33: ...he height of both modem aerials may improve the signal Once the limit of the Radio Modem has been reached a reduction of the operating distance by at least 20 is recommended to ensure a reliable link is achieved Note that the radar test may report missed packets that are not a direct result of interference Other radio modem pairs may be operating within radio range thus causing occasional missed o...

Page 34: ...ype connector fitted to the side of the radio modem The DTR signal into the Radio Modem is used to wake up the Radio Modem The Radio Modem can be forced into a permanently power up state by disabling DTR control in the configurator Pin 2 3 4 5 7 8 Other pins Connection DTE naming Receive Data Transmit Data Data Terminal Ready Signal Ground Request To Send Clear To Send No Connection Direction Outp...

Page 35: ...em DCE D9F PC connector 9 way to radio modem 9 way 2 3 4 5 7 8 3 2 20 7 4 5 Receive Data Transmit Data Data Terminal Ready Signal Ground Request To Send Clear To Send PC Serial Port DTE D25 Radio Modem DCE D9F PC connector 25 way to radio modem 9 way When using the Radio Modem with equipment capable of RTS CTS hardware flow control it is always advisable to enable it to prevent the possibility of ...

Page 36: ...connection to the radio modem Three Wire Half Duplex Interface The radio modem can be used for a basic three wire half duplex serial link employing either software handshake or no handshake at all The serial link into the radio modem is operating as a full duplex link however the radio transfer is a half duplex link In this example with no wake up signal provided by DTR so the Radio Modem is requi...

Page 37: ...5 7 8 6 4 1 2 3 5 7 8 6 4 1 Receive Data Transmit Data Signal Ground Request To Send Clear To Send Data Set Ready Data Terminal Ready Data Carrier Detect DTE Host D9 Radio Modem D9F RMX232 to DTE host interface 2 3 5 7 8 6 4 1 2 3 5 7 8 6 4 1 Receive Data Transmit Data Signal Ground Request To Send Clear To Send Data Set Ready Data Terminal Ready Data Carrier Detect DCE Host D9 Radio Modem D9F RMX...

Page 38: ...D TXD RTS CTS DTR GND Power down control Via DTR software selectable Power Interface 2 5mm DC power socket Antenna SMA connector on all models LED Indicators Radio Transmit Receive Red Green Radio Receive Data Red Modem Status Yellow Operating Temperature 10 degrees to 60 degrees C Line of Sight Range Outdoors VHF 100mW up to 5km Outdoors VHF 10mW up to 1km Outdoors UHF 25mW up to 800m Outdoors UH...

Page 39: ...ensitivity 100 dBm for 1ppm BER Antenna Female SMA gold plated antenna connector Impedance 50 ohms Ordering Information RMX232 151 275P 100mW TX Australia RMX232 151 300P 100mW Tx Australia RMX232 151 600P 100mW Tx Australia RMX232 173 225 10mW Tx Europe RMX232 173 250 10mW Tx Europe RMX232 173 225P 100mW Tx New Zealand RMX232 173 250P 100mW Tx New Zealand RMX232 433 920 10mW Tx Aus NZ Europe RMX2...

Page 40: ...mation RMX232 433 UHF Radio Modem Firmware V2 00a xxx Additional Information Major Number Minor Number Revision Letter Product Name Product Name Identifies the major product category name Major and Minor Number The major number reflects the hardware compatibility of the firmware It may also be incremented upon a major overhaul and upgrade of the firmware The minor number is incremented as new func...

Page 41: ...story Bug Fixes Change History Version 2 00a First release of the RMX232 Radio Modem The RMX232 has been ported from the original RM 232 radio modem thus all issues and bug fixes have been ported and included in this release of the RMX232 User s Guide ...

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