Modem Series User Manual
Contents
1. 8 SP1CTS SP1 DCD SPI DCD SP2TXD SP2 TXD 13 SP2 RXD SP2 RXD SP2 RTS 16 SP2 RTS J 17 SP2CTS 18 SP2 CTS J 19 SP2DCD J 20 SP2 DCD 21 DCGnd CS0EN 22 0 0 2 b6 amp d E E 28 sei 29 sVSeral 5VSera 2070 6x Series User Manual A01567 Rev A and Later 5 INSTALLATION Prior to installation the 2070 6x must be configured to match the system requirements Access to the two configuration switches is not possible once the module has been installed in to a 2070 controller There are accessible front panel configuration switches It is recommended to set these prior to installation as well After the configuration has been set insure that the front panel ON OFF switch is in the OFF position and then install the 2070 6x in to the controller While this can be performed with the power on to the controller it is recommended that the power be first turned off if possible Then turn the power on if it was previously turned off and then move the ON OFF switch to the ON position Configuration Function Table Switch FUNCTION OFF ON Full Duplex Disable Test Only Half Duplex Disable Test Only CTS Delay 12ms 6ms Soft Carrier Time 10ms 5ms Local Echo Disable Test Only Rec Squelch 6 5ms 3 25ms Time DCD Time 8ms 4ms L2. GDI Communications LLC Transportation Communications Specialists 2070 6x Modem Series User Manual Model Baud Rate bps 2070 6A 0 1200 2070 6AE 0 2400 2070 6B 0 9600 2070 6BE 0 19200 Dual Modems For The 2070 Controller GDI 2070 6x Series User MANUAL Document A01567 2070 6x V4 Rev A and Later GDI 2070 6x Series User Manual Hev A Proprietary Data This document contains confidential proprietary data with all rights and titles reserved by GDI Communications LLC By accepting this document the recipient assumes custody herof and agrees not to dislcose this data or any portion of this data to any unauthorized person without the prior written consent of GDI Communications LLC Recipient further agrees not to incorporate these drawings specifications or technical information in whole or in part in any other product or endeavor THIS LEGEND SHALL BE INCLUDED ON ANY REPRODUCTION OF THIS DOCUMENT GDI COMMUNICATIONS LLC 280 I 80 West Exit 1 PO Box 1330 Verdi NV 89439 Phone 775 345 8000 Fax 775 345 8010 TABLE OF CONTENTS GLOSSA RY ees ev os ense a see ru sa see e ea uo egeo uos ee an ua ee ee on Gao eG rn baeo ee vn Gao eden a Ga eden Pa oe ee a Sa SEE sa Sa an 1 GENERAL DESCRIPTION ceeeeeeececececececocecocesooe00000000000000000000000000000000000000000000000000000000 2 GENERAL CHARACTERISTICS e eeeeeee eee eee eee e ee eee eee e e e eee eee e e e e e e e
3. When TXD is at the Space level high Q19 is on Q25 is off Q24 is off and Q28 Q29 are both off setting the frequency to 2200Hz The output of the oscillator is then applied to the output amplifier U41D which is controlled by VR5 It is then routed to transformer T4 where it is coupled to the transmission network with a termination impedance of 600 ohms 2070 6x Series User Manual A01567 Rev A and Later 11 RECEIVE When the modem is configured for Full Duplex operation the incoming FSK signal is coupled to the receiver through 600 Ohm transformer T3 In Half Duplex operation the receive signal comes from the transmit transformer T4 The receive signal is buffered and amplified from the transmission line by U16A It is then band pass filtered by U16B and U16C to get rid of noise It is then amplified again by U16D and U20A to achieve a signal that is hard limited to VCC and then routed to the demodulator section of the Modem The demodulator consists of two band pass filters One set to the mark frequency and one set to the space frequency When the input signal is at the mark frequency the mark filter has maximum output and the space filter has minimum output The opposite is true when the input signal is at the space frequency The outputs of the filters are connected to opposite sides of rectifying diodes The mark filter is connected to the anodes and the space filter is connected to the cathodes Thus when the
4. controllers It compensates the inversion that occurs in the standard EIA RS232 RS485 line drivers and receivers 2070 6x Series User Manual A01567 Rev A and Later 7 TYPICAL SYSTEM OPERATION FULL DUPLEX systems use 2 pairs of wire to interconnect the Master and Slave modems Audio Out from the Master modem connects to Audio In of all the Slave modems The Audio Out of all the slave modems are connect together and returned to the Master modem s Audio In In this system it is possible to transmit in both directions at the same time HALF DUPLEX systems use 1 pair of wires to interconnect the Master and Slave modems All of the AUDIO OUTs of all of the modems are connected together Because the Master and the Slaves share the same wires transmission is one way or the other but not both at the same time In both systems the Slave Controllers can not transmit at the same time since they all share the same wire Additionally when using Half Duplex the Slave Controllers can not transmit at the same time as the Master and vise versa In Half Duplex there is less time between transmissions for the energy on the line to dissipate This energy on the line can interfere with the receiver circuits This makes the half duplex system more error prone than a Full Duplex system of the same length and wire type Proper use and timing of the EIA RS232 RS485 control signals are essential to proper operation of an FSK Modem syst
5. e e ee 3 INSTALLATION ite eret 660 os Sees eaae desea ope argo Ce e se e aa teet eaae eae as co Pene so cate e s sas 464 ea Deve sea Gene eu Soes 5 CONFIGURATION FUNCTION TABLE eese ee emen en eene nnhen etes essen esie sees es nenne nan 5 TYPICAL SYSTEM OPERATION 2 5024542 45 eet te ect ede eue tette ete Pee pe ce ota e EE Teo 7 HAT EDUPLEEX 325 esten De enden rete eti tei 7 HOW FAR WILL THE SIGNAL GO cccccccccccccccccccccccccccccccccccccccccccccccccccccecececesceceeaas 8 ADJUSTMENTS vcssisiciescscsccsssiccecessscsccesssccscscssisccsescscsscessiccocssscsvecevssscscsesscsecesssscscsescsvsseuss 9 THEORY OF OPERATION ccceeeeeecccccccecccccccccccccccocecocececocococococosocececesesesesesesessseseueueues 10 BLOCKDIAGRAM 2 2 23 sons sacs N meets ceto A e ene d At n Cea etes adc deve aee p duca vede s ded Desens 12 PREVENTATIVE MAINTENANCE scccccceseececcescececceccececcsceccecssecceccsseececceseeceeceseececeeners 13 TROUBLE ANALYSIS sic te clecsveccvszdessbsesbeveoelddlestesss eet drece dbdestessabesecetenys 13 TROUBLESHOOTING CHECKS ccccccccccccccccssssssseccccceccuscssescccccssssuensscseescsesssesueusesceeseeees 14 VOLTAGE MEASUREMENTS ccssessscsccccccccssesssescccccescusussesceccssssseeussssessceseseusueaseescesseees 14 ALIGNMENT PROCEDURES ccssssssceccccccccessssscecceccccessusssescecccssssuesseesesscssssseuueasseseeseeaes 14 2070 6x Series User Manual A01567 Rev A and Later 1 GLOSSARY DTE Data T
6. mark frequency is detected the output of the demodulator is positive and when the space frequency is detected the output of the demodulator is negative The outputs of the two sides of the demodulator are combined by U20B However the output of the demodulator still has some frequency components that must be filtered out This is accomplished through a series of low pass filters U23A U23D At the output of this 4 element filter the signal has been converted from frequency based coding to binary coding There are three other paths that the signal takes to qualify it U26A and U26B comprise a carrier integrates the signal into a positive DC level that is used to trigger the carrier detect timer The signal must be present long enough for the timer to reach a high enough level to switch the DCD output switch U25C There is also an inband detect filter U20C and a soft carrier detect filter U20D that must be satisfied to enable the RXD output amplifier While the In Band filter enables the RXD output the soft carrier detector disables the RXD output The RXD output and the DCD signals are then routed through the signal control and routing PLD The output of the PLD is then routed to opto isolators and then line drivers U34 and U39 where the signal is converted from TTL back to EIA 485 levels Relay K1 is part of the soft start power control The front panel ON OFF switch makes a current path for the relay power and
7. the soft start circuit 12 2070 6x Series User Manual A01567 Rev A and Later Block diagram ino oipny dwy indu J9 II4 ssedpueg dwy jndino Jo0jejeq K6Jou3 dwy uojenbs J8AI929M ouo 9 Suru joquog jusuelj J0 09 8q Jausep yos J0 29 19q pueg ul 1ojejnpouieq JOojejrso JOoJei6aju yojanbs jouog uojejnpoja oejeg saweg JONUOD 9 je ug ndino axy S19 Sly axl 2070 6x Series User Manual A01567 Rev A and Later 13 MAINTENANCE Preventative Maintenance The only preventative maintenance required is the maintaining of the environmental parameters of which the modem is operating This includes but not limited to temperature and supply voltage Trouble Analysis The model 2070 6x is a fairly complex Modem with hundreds of parts This makes this Modem hard to troubleshoot for the average technician with limited experience It also requires special soldering tools to work with the surface mount parts On the other hand this modem is constructed with top quality parts and so you will not experience many failures 2070 6x Series User Manual A01567 Rev A and Later Troubleshooting Checks Voltage Measurements For DC Isolated Models TP Measurement tolerance TP27 5vdc 2vdc TP30 5vdc 2vdc TP33 5vdc 2vdc TP34 3 3vdc 2vdc For non Isolated Models TP Measurement tolerance TP27 12vdc 6vdc TP30 12vd
8. c 6vdc TP33 5vdc 2vdc TP34 3 3vdc 2vdc Alignment Procedures All alignment is performed at the factory The modem is a single board plug in module and does not require further alignment 2070 6x Series User Manual A01567 Rev A and Later GDI COMMUNICATIONS LLC 280 l 80 WEST EXIT 1 PO BOX 1330 VERDI NEVADA 89439 TELEPHONE 775 345 8000 FAX 775 345 8010 15
9. djusting the amplitude of the output signal Adjusting the output amplitude potentiometer clockwise will increase the amplitude of the output signal These potentiometers are labeled AMP A for channel A and AMP B for channel B There may be more crosstalk problems in some cable systems with the increased output The operating frequency and the number of units on a line will determine the total distance The higher the frequency the shorter the distance Additional distance can also be gained by switching the modem s input impedance on the middle units of a system The input impedance of the Modem can be switched from 6000 to 4 75K0 The Modems on the ends of the line should be left to 600 Ohms This will reduce the loading effects of each additional modem on a string 2070 6x Series User Manual A01567 Rev A and Later ADJUSTMENTS The 2070 6x will not normally need any adjusting The adjustments are factory set and will not require adjusting with the possible exception of the output amplitude A factory test procedure with full instructions on how to test and setup the modem will be provided on request 2070 6x Series User Manual A01567 Rev A and Later 10 THEORY OF OPERATION Frequencies are based on the 2070 6A Both channels of the 2070 6x function the same Channel 1 is connected to SP1 SP3 of the controller and Channel 2 is connected to SP2 SP4 of the controller TRANSMIT EIA 485 signals on the backplane o
10. em These signals are RTS CTS and DCD RTS is an input to the Modem that turns the transmitter ON When RTS is asserted the Modem is transmitting a Mark signal The Mark Frequency is maintained and used to enable receivers on the connected MODEMS After 12ms the modem asserts the CTS signal This enables the controller to start transmitting data The 12 ms delay provides a time window for the receiving modem s carrier detect circuit to detect and verify the Mark frequency which takes 8ms If data is transmitted prior to this the receiver may chop off the first portion of the data or the receiver may never validate the signal After the data packet has been transmitted the controller de asserts RTS and then transmits the soft carrier frequency for 10ms The soft carrier frequency is detected by the receiver and shuts down This prevents excess energy on the line from reaching the controller 2070 6x Series User Manual A01567 Rev A and Later HOW FAR WILL THE SIGNAL GO This is an important question in higher speed FSK Modem operation Typically with a 0dBm launch signal you can expect about 10 14 miles on 22AWG wire A 25 increase can be gained by using 19AWG wire The operating frequency and the number of units on a line will determine the total distance The higher the operating frequency the shorter the distance The more units attached to a line the shorter the distance More range can be gained by a
11. erminal Equipment A device that initiates communication DCE Data Communications Equipment A device that converts data from a DTE to a transport stream For example The GDI model 2070 6x modem is a DCE that converts RS485 data from a 2070 controller to FSK for transmission Host Any DTE device Full duplex A communication system where data can be transmitted in both directions at the same time Half duplex A communication system where data can be transmitted in only one direction at a time FSK Frequency Shift Keying Communication protocol where data is encoded into binary format and represented by different frequencies Private wire Twisted pair galvanic wire or Telco communication hardware that is leased for private use 0 dBm Represents the signal level required to produce 1mw in a 6000 load Surface mount parts Electronic parts that are designed to be soldered to pads instead of vias MARK Signal state of a FSK system that represents a logical 1 value SPACE Signal state of a FSK system that represents a logical 0 value SOFT CARRIER Frequency transmitted to squelch Remote TXD Transmit Data A data signal that transfers information in form of binary data from a DTE RXD Receive Data A data signal that transfers information in form of binary data to a DTE RTS Request To send A control signal that can be used to gate TXD to a DTE The DTE asserts RTS and the
12. f the 2070 controller are converted to TTL signals by line receivers U33 and U37 The outputs of these LTC488 receivers are then routed to opto isolators which provide isolation between the controller and the transmission line The outputs of the opto isolaters are then routed to the signal routing and control PLD U43 U43 is a state of the art Programmable Logic Device that has been designed to control and route the signals The configuration switches determine how the signals are routed and controlled through the PLD The outputs of the PLD are then routed to the Modulation section of the Modem Here the digital signals Mark and Space are converted to their respective transmission frequencies of 1200Hz and 2200Hz This process of converting digital signals to frequencies is called Frequency Shift Keying FSK Where a frequency of 1200Hz represents a mark signal and the frequency of 2200Hz represents a space signal The transistors used in this section are operated in the saturated modes of on and off and therefore act like switches They are arranged so that the oscillator U41 is switched between the various frequencies Normally the oscillator is running at the soft carrier frequency of 900Hz When RTS is asserted Q22 turns Q27 off thus changing the frequency to 1200Hz if TXD is in the mark state With TXD in the mark state Q19 is off Q25 is on Q24 is on and Q28 Q29 are both on setting the frequency to 1200Hz
13. g between the transmitting modem and the receiving modems Anti Streaming The 2070 6x employs two modes of anti streaming Anti streaming is a safety feature of the modem that monitors the transmission signals of the controller and turns it off if the controller is still transmitting after 7 seconds This is to prevent a single remote controller from jamming signals for the other remotes in the network When switch 10 is in the ON position the 2070 6x monitors the RTS signal When the RTS signal is asserted the anti streaming timer starts counting seconds After 7 seconds if the RTS signal is still asserted the anti streaming turns off the modems transmitter When switch 10 and switch 11 are ON the 2070 6x monitors both the RTS and the TXD signals While RTS is asserted the TXD signal is monitored for activity If there is a break in signal activity on TXD lasting longer than 7 seconds the modem s transmitter is turned off RTS only anti streaming should be used on remote units only as the master controller is typically in constant transmit mode The TXD anti streaming can be used with the master controller Switch 12 should normally be set to the default OFF position for most 2070 controllers If required the controller interface signals can be inverted by setting this switch to the ON position NOTE The Normal position of switch 12 actually does perform an inversion of the signal which is normal for most
14. n waits for the DCE to respond with CTS CTS Clear To Send A control signal that can be used to gate TXD data from a DTE DCD Data Carrier Detect A control signal that can be used to gate RXD to a DTE Anti Streaming A function on GDI modems that prevents a Host from transmitting continuously 2070 6x Series User Manual A01567 Rev A and Later 2 GERNERAL DESCRIPTION The 2070 6x Modem is a dual FSK Modem for the 2070 Controller which utilizes the latest surface mount technology The GDI 2070 6x meets or exceeds the CALTRANS Transportation Electrical Equipment Specifications TEES of March 12 2009 and applicable addendum This Modem plugs into the A1 to A5 slots of the 2070 Controller and is held in place with two thumbscrews The front panel has two M14 type connectors that are identical to the C2S and C20S connectors on the 170 Controllers Therefore cables made for the 300 series cabinets will work with the 2070 6x The 2070 6x also converts the EIA 485 signals for SP1 2 or SP3 4 on the back plane of the 2070 to EIA 232 These signals are available in the M14 C2 and C20 connectors on the front panel When the Modem sections are not being used a front panel switch can turn off each section of the Modem individually so that it doesn t interfere with the EIA 232 communication To use the C2S C20S connectors for EIA 232 switch the associated front Panel Switch to the DISABLE position The FSK MODEM i
15. oad Compensation RTS Override Hi Z 6000 Active Constant Anti Streaming Disable 7s Anti Stream TXD MON RS 485 Disable 7s Normal INVERT NO INVERSION For normal 4 wire full duplex operation all of the switches should be OFF Except Switch 8 ON If 2 wire FSK half duplex operation is required set the front panel switch to HALF DUPLEX Switches 1 2 and 5 are used in the factory for test purposes and should be left in the OFF position The Control signal timings are configured by switches 3 4 6 and 7 In the off position the timings are set for the standard times as described in the California TEES specification It is possible to adjust the timing in half by setting these switches to the ON position This will serve to speed up the response time of remote units However it may inject more data errors in the system 2070 6x Series User Manual A01567 Rev A and Later 6 Switch 8 sets the input impedance of the receiver For normal applications it is set to the ON position which connects a standard 6000 load across the input In the OFF position the input is set to HI impedance This can be used to compensate for low signal However it is highly recommended that all the modules in the same network be set the same except first and last unit in string Setting units to the normal 6000 will reduce the amount of signal noise by maintaining the balance of loadin
16. r end Separate switches also allow the timings on the handshake and modem control signals to be cut in half for faster communications 2070 6x Series User Manual A01567 Rev A and Later 3 General Characteristics Physical 220mm x 177mm x 40 44mm TIMINGS Clear To Send Temp 37 to 74 degrees C CTS Delay 12ms 2m 6ms Soft Carrier Time Humidity 5 to 95 non condensing Frequency transmitted to Power 5 V 500ma squelch Remote bd PIE 100 ma Rec Squelch DCD Data Rate Bps Rec line Signal eas gA R RSS Eu Modem Recovery Time 14 ms 2070 6B 0 9600 M Error Rate lt 1 in 1 N of 16 dB 2070 6BE 0 19200 rror Rate in 10 S N of 16 d Modulation Phase Coherent FSK Anti streaming time out 7 sec Data Format Asynchronous serial by bit C2 and C20 Pinout Function Line interface Private Metallic wire 600 Ohm or HI Z selectable Audio In 2070 6A can also operate over the telephone company 3002 type leased lines Out D 5VDC M Out F NA H cD Frequenc DC Gnd 1 Model ed FUNCTION DOWN FULL HALF DUPLEX FULL HALF Receive Sensitivity 0 to 40 dB ENABLE DISABLE 3 POWER ON OFF Output Level 8 to 0 dB cont Adj BEC EAON a SORES set to OdB 2070 6x Series User Manual A01567 Rev A and Later 96 pin connector pin out for the 2070 6x A Pint A a pr SPTRTS 7 ISPEOTSR D gt
17. s enabled in the ENABLE position FSK Full Duplex or Half Duplex can be set for each channel A 5 switch powers down the entire Module so that it can be inserted or taken out while the power to the 2070 is on This prevents any of the parts on the 2070 6x Modem or the 2070 Controller from being harmed during insertion or being unplugged Six LEDs are also located on the front panel 3 for each channel They include Transmit Data TX Receive Data RX and Carrier Detect CD All of the RS 232 FSK signals in the C2S and C20S connectors are optically isolated from the controller signals The 5V supply and Ground in the C2S and C20S connectors are also isolated and individually fused at 200ma with a solid state PTC to protect the 2070 s internal power supply The 2070 6x Module is built with surface mount parts for increased reliability and to reduce the parts count The use of all surface mount parts has allowed us to put all of the parts on a single PC Board The digital section and first modem are on the top side of the board The second modem is on the back of the PC Board Power and Ground planes prevent crosstalk and isolate the two modems from each other The GDI 2070 6x also has an anti streaming option that can be selected with a dipswitch on the PC Board Anti steaming will prevent a remote site from monopolizing the communication path in a multi drop configuration Anti streaming is not normally used on the Maste
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