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AN122 M7 and SCADA.

1. ATXR Enable Disable repeater function Only enable it on the particular radio that will be the repeater ATX1 N A 1000 0000 1000 0000 N A In the repeater set the addresses this unit will store and repeat to from By setting the repeater address mask to Technical Brief AN122 Raveon Technologies Corp 0000 this repeater will repeat any and all data packets Serial Port RS232 or RS485 Raveon s M5 and M7 radio modems come standard with RS 232 serial ports They may be ordered with an RS 422 and RS 485 options For SCADA systems a typical configuration is to have the radio modem connected to the HID computer to have an RS 232 serial port The RTUs in the field usually use RS 485 so the radio modems connected to the RTUs should have the RS 485 option installed A system may mix RS232 and RS485 modems with no adverse consequences Buffer Status On the M7 series of radios there is a command ATJF that will allow the user to set the CTS threshold By default this is set to 80 of the buffer s size When the internal data buffer of the M7 reaches this threshold the CTS hardware handshake line is negated The user may change this threshold If you want the M7 CTS line to indicate when there buffer is empty all data has been transmitted then set the ATJF parameter to 1 ATJF 1 This will have the effect of negating CTS whenever there is any data in the M7
2. radio modem compatible with most every PLC PC and HMI device made Programmable over the air data rates With the M7 radio modem you can choose how your system will work Set the OTA data slower for extended communication range or set it fast for lowest latency Your choice SkyLine compatibility mode for use in older Sonik radio systems Going Wireless Wired Connection The telemetry industry has standardized on a number of different protocols to use in these types of applications Most protocols were based upon the assumption that the cabling between the monitoring station and the RTU PLC is an RS 232 or RS 422 serial link The protocols commonly used on these serial links are MODBUS RTU MODBUS ASCII DF1 DNP 3 and IEC870 All of these protocols can operate using hard wired connections Because the Raveon Radios mimic a hard wire data in equals data out in most cases the protocols will also work using a wireless modem M7 Modems with Modbus Raveon radio modems support Modbus ASCIl networks with no special configuration Modbus ASCll was designed specifically to work well over wired and wireless modems and uses 7 bit data All Raveon modems support 7 bit data Modbus RTU uses 8 bit data Some modems and older systems do not work with 8 bit data but Raveon s wireless modems support both 7 bit and 8 bit data There are some considerations when using radio modems with Modbus RTU Latency The difference between M5 and M7 seri
3. response back is 150mS in Packet Mode Copyright 2006 5 Raveon Technologies Corp Last updated January 2013 A DF1 polling system with M5 Fireline or M7 modems configured for 8000 baud over the air 9600baud serial ports 2mS time out and Streaming Mode will allow RTU s to be polled and responses returned in about 80mS round trip R epeating For Extended Range For longer communication ranges high RF noise environments or obstructed line of sight applications it may be necessary to use a repeater to establish a reliable communications link Le Monitoring Station Repeater Modem RTU or PLC Incorporated in the radio is a built in store and forward repeater function The repeater function works only in the Packet Mode and will not repeat streaming messages A repeater can extend the range of a system by 2 20X depending upon how high up above the average terrain the repeater is mounted The following table shows a typical repeater system configuration in packetized mode AT Comman d Monitorin g Modem Repeater Modem Remote Modem Notes ATMY 1000 2000 0001 0999 Individual unit address for this particular modem Each remote modem should get a unique ID ATDT 0001 N A 1000 Destination address to send data to ATMK F000 0000 F000 Address mask F000 means that to receive the first digit of the MYID must match the first digit of the TOID
4. s data buffer When all data has been transmitted over the air the CTS line will be asserted again It is a handy way to receive a hardware indication that a transmission has gone out and the radio is ready for more data But remember regardless of the ATJF setting the M7 s data buffer can hold thousands of bytes of data queuing them up to be sent over the air The ATJF command only affects the threshold where CTS is asserted not the size of the internal data buffer in the 7 For additional information contact Raveon Technologies Corporation 2461 Impala Drive Carlsbad CA 92010 USA Phone 1 760 444 5995 Fax 1 760 444 5997 Email sales raveon com Copyright 2006 7 Raveon Technologies Corp Last updated January 2013
5. Technical Brief AN122 Raveon Technologies Corp Ze Technical Brief Raveon AN122 Rev c1 w amp r M7 Series Modems for SCADA Applications By John Sonnenberg Raveon Technologies Corp Summary The M7 series of data radios from Raveon Technologies make ideal wireless modems for SCADA and telemetry systems This Application Brief describes the general requirements for a wireless SCADA modem and then provides the information needed to configure an M5 or M7 series modem to work in common SCADA applications Wireless SCADA In a traditional wired SCADA system a device is monitored by some type of computer or other human to machine interface The user may have something as simple as an LED indicator or as complex as a computer server for the operator The human interface communicates to another electronic device that is remotely located at the monitored location Often this remote device is a Remote Terminal Unit RTU or Programmable Logic Controller PLC Copyright 2006 1 Raveon Technologies Corp Last updated January 2013 Typical SCADA System g Monitoring Station 7 RTU or PLC When the distance between the monitoring station and the device being monitored the water tank above is not trivial than a wireless link between the two sites becomes a logical means of connecting them i RTU or PLC Wireless Modem Monitoring Station Wireless Modem Raveon s Features for SCADA Applicatio
6. es wireless modems and a multi drop wired network is that the wireless modems introduce some additional latency delay into the system Most Modbus RTU applications can tolerate this latency but some cannot If your Modbus application does not tolerate Copyright 2006 3 Raveon Technologies Corp Last updated January 2013 latency then use Modbus ASCII Modbus ASCIl is compatible with Raveon radio modems The following table shows Latency vs Over the air bit rate for Raveon narrow band radio modems in the packetized mode Bit Rate ATR2 Setting Latency Seconds 800 2L 0 0 8 0 9 1200 2L 1 0 5 0 6 2400 2L 2 0 3 0 4 4800 2L 3 0 2 0 3 5142 2L 7 0 2 0 3 8000 4L 4 0 2 0 3 Time Outs Some versions of the Modbus protocol have short response timeout requirements that may not be compatible with radio modem latencies Modbus RTU is compatible with the normal FireLine latencies but does have inter character delay requirements that must be met Raveon modems have programmable time outs to facilitate the control of latency Modem IDs The M5 and M7 series modems have 16 bit IDs Most SCADA systems work in a broadcast configuration where all modems hear all other modems To do this set the net mask to all zeors ATMK 0000 Be sure to set each unit ID in each modem to a unique ID number so that the duplicate packet filtering works properly All Raveon modems filter out duplicate packets so that ope
7. ir bit errors and in most cases works well in streaming mode In Technical Brief AN122 Raveon Technologies Corp mission critical or safety situations packet mode would be more appropriate as it s data transmission is more deterministic Configuring the M5 or M7 Radio For SCADA applications configure the radio as per the user manual In most cases the factory defaults are the best place to start Set the frequency using the ATFX XXX XXXX Command Then based upon your system configure the following parameters AT Function command ATBD Set the baud rate of the FireLine s serial port Typically set the serial port rate to 2400 or 9600bps whichever matches your hardware s setting Given a choice Raveon suggests you set it at a high rate to reduce latency 9600 is set with the ATBD 3 command 19200 is set with the ATBD 4 command ATBC Enable disable Busy Channel Lockout Normally the radio modem does not check for a busy channel If you are running a large system with asynchronous data on the radio channel you should enable BCL so the modem does not transmit while another device is on the air For polled telemetry systems do not enable this feature ATCH Enable Disable hardware flow control By default this is off and will work fine in most applications Enabling hardware flow control will ensure that the modem buffers data and only outputs it to the user s device or RTU when the device is ready to recei
8. ns High speed over the air data rates 19200bps in 25kHz channel 9600bps in 12 5kHz Remote status monitoring including DC voltage packet error statistics modem up time and receiver signal strength Easy to use Plug in Turn on and GO Transmit data in Receive data out Lowest current draw in industry The M7 wireless modems draw less than 90mA in the receive mode Wide input voltage with high efficiency switching voltage regulator Technical Brief AN122 Raveon Technologies Corp Packetized AND Streaming Data Integrated Packetized data protocol with error correction and built in Streaming Real Time operation User selectable ARQ error correction and retransmission capability Totally transparent to the application Capable of store and forward repeating operation Small size Extruded aluminum enclosure is small and very rugged 16 bit addressing for up to 65 525 different unique device addresses per channel Radio channels may be shared with no interference between users Supports group and broadcast transmissions Network mask allows groups of any size Easily to configure Raveon modems are configured using AT commands through the modem s serial port Raveon also provides free of charge Radio Manager a easy to use PC program with a graphical user interface to configure and program all Raveon Radios RS 232 RS 422 or RS 485 serial port Programmable serial baud rates up to 115200 make the M7
9. ration with repeaters does not cause duplicate packets being received For lowest latency Raveon s unique Streaming mode of operation provides data transfer with latency only slightly higher than wired configurations No other radio modem on the market offers both error free packetized operation AND Streaming data operation M7 Modems with DF1 The DF1 protocol works well with the Raveon radio modems as long as the over the air data rate is set to 4800 bps or higher The stock configuration of the radio modem works with the Rockwell DF7 Polling Driver To reduce latency in the polling it is suggested that certain stock parameters in the FireLine be a adjusted to values more optimized for use in a polled environment The following is a list of parameters in the radio that may be adjusted to reduce latency when using the DF1 protocol 1 Reduce the serial port time out value down to 2mS ATR3 2 2 Set the serial port to 19200bps ATBD 4 3 Configure the Over the air data rate to 8000bps ATR2 4 This will reduce the communication range so only do this if the link margin on the system is adequate 4 Use the Streaming Mode of communications ATMT 2 The factory default is the Packet Mode where all data is error checked and sent in packets The Streaming mode initiates transmissions faster and sends characters over the air as they stream in but does not check for errors DF1 is tolerant of noise and over the a
10. ve it ATFX Used to set the radio frequency of the modem ATNB Set the parity bit method of the serial port Odd even none mark or space You must configure this to match the device the FireLine is communicating with Note Parity baud Rate and stop bits may be configured differently on different ends of the radio link ATR2 The over the air data rate For long range set it at 4800bps For lowest latency set it at 8000bps or 9600bps ATR2 3 for 4800baud ATR2 4 for 8000 baud ATR3 Serial port time out This is the amount of idle time in mS before the FireLine will begin to transmit a packet of data When no data comes into the modem for this amount of time the FireLine will transmit the contents of its data buffer over the air The factory default setting is 20mS For SCADA systems using MODBU 2mS is suggested ATR3 5 ATMY The M5 and M7 series modems have 16 bit IDs Most SCADA systems work in a broadcast configuration where all modems hear all other modems Be sure to set the unit ID in each modem to a unique ID number so that the duplicate packet filtering works properly ATMK To turn off address filtering and allow all units to receive data from all other units set the net mask to all zeros ATMK 0000 For example with a modem configured for 8000 baud over the air 9600baud serial ports 2mS time out the total time for a MODBUS Read Module Name command 01M command to receive the

AN122 M7 and SCADA.

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