Embedded RM232-433 User Manual Download

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Embedded Communications Systems

Specialists in Embedded RF Data Communications,

Monitoring and Control Systems

RM-232-xxx Radio Modem

User’s Guide

N11391

Summary of Contents for RM232-433

Page 1: ...Embedded Communications Systems Specialists in Embedded RF Data Communications Monitoring and Control Systems RM 232 xxx Radio Modem User s Guide N11391 ...

Page 2: ...e radio modem and 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 Regulation...

Page 3: ...iguration Mode 3 1 Command 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...

Page 4: ...o Wire Simplex Interface 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 ...

Page 5: ...vides the capability of a short range reliable wireless point to point and point to multipoint RF data communications link The RM 232 can be used 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 dev...

Page 6: ... Point to Point and Point to 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...

Page 7: ...rating 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 Follow the steps below to connect the RM 232 radio modem to your computer Co...

Page 8: ...Alkaline 9V PP3 Battery Recommended battery placement The Radio Modem is fitted with a DC power socket for use with an external regulated 9 12VDC power source The diagram below shows the power socket polarity Plugging an external power source into the DC jack effectively disconnects the internal battery if one is installed DC Power Jack Positive Negative Power socket type and polarity Contact your...

Page 9: ...odem to the ON position as shown in the diagram below ON Slide the power switch to the ON position Once power is applied to the radio modem you should see a welcome message appear on the communications application display as shown below The displayed mode of operation will change to reflect the currently configured mode of the radio modem Signon message as displayed upon power up As the signon mes...

Page 10: ...en flash Radio in standby mode waiting to establish a link Receive Red Radio receiving data Status Single pulsing Radio Modem is active but no link is established Status Double pulsing A link to a Remote device has been established Status On Off 0 5 sec Attempting to connect to a remote Radio Modem Status On Off 2 secs Low battery indication Two second flash rate Status On Radio Modem is in setup ...

Page 11: ...mance of the radio modem Ensure the antenna is kept away from potential sources of RF interference such as electrical wiring transformers batteries and other items of electronic equipment Where possible ensure the Radio Modems are placed well above head height The higher the better It is wise to try different locations and positions for the radio modem before permanently mounting it When trying ou...

Page 12: ...o either radio interference or an inadequate radio path Prior to deploying a new installation a bench test of the system is highly recommended as a method of eliminating basic operational and system configuration problems Inadequate performance from the bench test may require fine tuning of the configuration parameters It is recommended that for any new site installation a radio site test be perfo...

Page 13: ...ust be completed 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 accomplis...

Page 14: ...ent Radio Modem configuration This command 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 d...

Page 15: ...l effectively reduce the rate of data collisions and packet retries thus improving the overall network interoperability Command format airspd n where n 600 1200 2400 Applies to RM 232 151 173 600 1200 2400 4800 9600 14400 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 mode...

Page 16: ...to make in order for it to reach it s destination 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 i...

Page 17: ... an overview of using the addr function 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 set...

Page 18: ... monitoring This command enables or disables 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 ...

Page 19: ...t to the remote unit A data packet or it 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 st...

Page 20: ...the escape sequence signon Display sign 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 mes...

Page 21: ...command If no parameter is given the setting 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 th...

Page 22: ... Sets the modem to broadcast multidrop network 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 i...

Page 23: ...parity is enabled at the remote This makes 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 ...

Page 24: ...ds the buffer 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 con...

Page 25: ...rflowing If an overflow occurs within the radio 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 operat...

Page 26: ...site codes and unit addresses is to provide 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 exte...

Page 27: ...over each point to point link This is to be expected 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 ...

Page 28: ...trol enabled and is connected to a serial port 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 ...

Page 29: ...nce ID and a checksum value When a Radio Modem 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 devic...

Page 30: ...ode set to ON as in point to point mode In 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 T...

Page 31: ... a reply or just acknowledge receipt of the 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 o...

Page 32: ... and return ACK path with their respective 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 retr...

Page 33: ...ing acknowledgement from any radio modem that 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...

Page 34: ... dropouts are becoming apparent Increasing the 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 ...

Page 35: ...ay female D type 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 Radio modem DTE connector connections Pin 2 3 4 5 7 8 Other pins Connection DTE naming Receive Data Transmit Data Data Terminal Ready Signal Ground Request...

Page 36: ...lear To Send PC Serial Port DTE D9 Radio Modem 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...

Page 37: ...F Data flow via radio link Two wire simplex 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...

Page 38: ...ections shown in the following diagrams 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 DTE Host D9 Radio Modem D9F RM 232 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 Ca...

Page 39: ...ured as a DCE RS232 Signals RXD TXD RTS CTS DTR GND Power down control Via DTR software configurable Power Interface 2 5mm DC power socket Antenna Integral helical or wave whip for RM 232 433 SMA on all other models LED Indicators Radio Transmit Red Radio Receive Red Green Modem Status Yellow Operating Temperature 0 degrees to 55 degrees C Line of Sight Range with helical antenna fitted Outdoors u...

Page 40: ... 232 173 Single Channel VHF 173 250MHz Frequency RM 232 433 Single Channel UHF 433 920MHz Frequency RM 232 869 Single Channel UHF 869 850MHz Frequency RM 232 914 Single Channel UHF 914 500MHz Transmitter Power RM 232 151 10mW ERP Power RM 232 151P 100mW ERP Power RM 232 173 10mW ERP Power RM 232 433 10mW ERP Power RM 232 433P 100mW ERP Power RM 232 869 1mW ERP Power RM 232 914 1mW ERP Receiver Sen...

Page 41: ...Version Information RM 232 433 UHF Radio Modem Firmware V1 04a 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 incremente...

Page 42: ...d in the configurator when signon is set to off Added command ser to display serial number information in the configurator Added command ctime to allow setting of the connection duration Version 1 03a Added adaptive back off for data packet retries This removed the 1 second delay before packet retires Effectively speeded up transfers in noisy environments Added rptmode all to repeater mode This no...

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