Digicom LCM16P User manual

LCM16P
LCM16PR
USER'S MANUAL

II

III
LCM16P
LCM16PR
USER'S MANUAL
LCM16P LCM16PR rev.2.0 07/97 COD.7D0894
All right reserved; no part of this publication may be reproduced, stored in a retrieval system,
or trasmitted in any form or by any means, electronic, otherwise, without the prior written
permission of the publishers.
The contents of this booklet may be modified without prior permission.
Every possible care has been taken in testing and putting together all the documentation
contained in this booklet, however DIGICOM can not take any responsibility brought by
the use of this booklet.

IV
INDEX
PRECAUTIONS
1. INTRODUCTION 1.1
1.1. PRODUCT FEATURES 1.1
1.2. TECHNICALCHARACTERISTICS 1.1
1.2.1. DTE-DCE digital interface 1.1
1.2.2. Data input 1.2
1.2.3. Clock signal characteristics 1.4
1.2.3. RTS/ CTS circuits 1.4
1.2.4. Asynchronous Mode 1.5
1.2.5. Analog Interface: transmission line 1.5
1.2.6. Analog Interface: receive line 1.5
1.2.7. Receive time base (synchronous mode only) 1.6
1.2.8. C109 Circuit 1.6
1.2.9. Tests 1.7
1.2.10. Connection distance 1.7
1.2.11. Line connection 1.8
1.2.12. DTE connection 1.8
1.3. FUNCTIONAL BLOCK DIAGRAM 1.8
1.3.1. Datapump 1.8
1.3.2. Microprocessor 1.8
1.3.3. Line Interface 1.9
1.3.4. RS 232 Interface 1.9
1.3.5. Power supply circuit 1.9
1.3.6. Loop circuits 1.9
1.4. TRANSMISSION CIRCUIT 1.11
1.4.1. Digital section 1.11
1.4.2. Analog section 1.12
1.5. RECEIVER CIRCUIT 1.13
1.5.1. Analog section 1.13
1.5.2. Digital section 1.13
1.6. POWER SUPPLY 1.14
1.7. CCITT V54 RECOMMENDATION 1.14
2. THIS CHAPTER IS INTENTIONALLY BLANK 2.1
3. OPERATION MODE 3.1
3.1. DEVELOPMENT AND ACCESSORY 3.1
3.1.1. Technical characteristics 3.1
3.1.1.1. Mechanical Size 3.1
3.1.1.3. Power supply 3.2
3.2. COMMAND AND MESSAGE DEVICES 3.2
3.3. INSTALLATION PROCEDURE 3.4
LCM16P LCM16PR Index

V
3.3.1. Preliminary Operations 3.4
3.3.2. Modem installation 3.4
3.3.3. Electrical connections 3.4
3.3.3.1. Main power supply connection 3.4
3.3.3.2. Line connection 3.5
3.3.3.3. DTE interface 3.5
3.4. LCM16P AND LCM16PR PREDISPOSITION 3.5
3.4.1. Functional Description 3.6
3.4.2. Jumpers functional description 3.12
4. DIAGNOSTIC 4.1
4.1. INTRODUCTION 4.1
4.2. LOOP 3 ACTIVATION 4.1
4.3. LOCAL LOOP 2 ACTIVATION 4.2
4.4. REMOTE LOOP 2 ACTIVATION 4.2
4.5. TANDEM CONFIGURATION EXAMPLE 4.4
4.6. TEST DURING LOOP 4.5
DECLARATION OF CONFORMITY
TABLES INDEX
Tab.: 1.1. CCITT V24 INTERFACE SIGNALS USED IN LCM16P AND
LCM16/PR MODEMS 1.3
Tab.: 1.2. DELAY TIMES RTS/CTS 1.4
Tab.: 1.3. DCD DELAY TIME. 1.6
Tab.: 1.4. CONNECTION DISTANCE WITHOUT THE EQUALIZER 1.7
Tab.: 1.5. CONNECTION DISTANCES WITH EQUALIZER 1.7
PICTURES INDEX
Fig.: 1.1. FUNCTIONAL BLOCK DIAGRAM 1.10
Fig.: 1.2. MODULATION WAVEFORMS 1.11
Fig.: 1.3. BLOCK DIAGRAM 1.16
Fig.: 3.1. LCM16P FRONTAL VIEW 3.3
Fig.: 3.2. LCM16P BACK VIEW 3.3
Fig.: 3.3. LCM16PR FRONTAL VIEW 3.4
Fig.: 3.4. LINE CONNECTOR AND PINS ASSIGNMENT FOR LCM16P 3.5
Fig.: 3.5 LINE CONNECTOR AND PINS ASSIGNMENTS FOR LCM16PR 3.5
Fig.: 3.6. LCM16P TOPOGRAPHICAL VIEW 3.14
Fig.: 3.7. LCM16PR TOPOGRAPHICAL VIEW 3.15
Fig.: 4.1. LOOP 3 DIAGRAM 4.1
Fig.: 4.2. LOCAL LOOP2 DIAGRAM 4.2
Fig.: 4.3. REMOTE LOOP 2 DIAGRAM 4.3
Fig.: 4.4. TANDEM CONNECTION + MULTI- POINT 4.4
LCM16P LCM16PR Index

VI
LCM16P LCM16PR ENGLISH Index
PRECAUTIONS
The following installation rules should be respected in order to have the best working order of the
equipment an user’s safety.
Enviromental Conditions
Forall devices:
ENVIROMENTAL RELATIVE
TEMPERATURE HUMIDITY
from -5 to + 45°C from 20 to80% n.c.
Avoid rapid changes of temperature and humidity (0,03°C/ [min.]).
This system, including cables, should be installed in an area without or distant from:
lDust, humidity, elevated heat from direct sun light.
lObjects irradiating heat. These could cause damages to the container or other problems.
lObjects that cause a strong electromagnetic field. (HI-FI loudspeakers, Etc.).
lLiquids or chemical corrosive substances.
GENERALWARNINGSForallequipmentpowereddirectlyfromthenetwork
POWER SUPPLY 230 Volt 50Hz
ISOLATION CLASS only those indicated on the equipments label
NOMINAL CURRENTS only those indicated on the equipments label
To avoid electric shocks, the equipment should never be opened. Ask qualified personnel help.
To replace the fuse, remove the power supply cable.
Disconnect the power cable from the wall plug when the terminal is not used for a long period.
To disconnect the cable, pull it by the plug, never pull it by the cable itself.
If there should be a liquid or objet penetration in the equipment, disconnect the power cable and call the
qualified personnel for testing.
CLEANINGTHETERMINAL
Use a soft dry cloth. Wet the cloth with water or natural detergent if it is necessary to remove stains.
Never use chemical product such as petrol or solvents.
VIBRATIONS OR CRASHES Caution against vibrations and crashes.
WARNING
This is a class A product.
In a domestic environment this product may cause radio interference
in which case the user may be required to take adeguate measures.

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1.1
LCM16P/LCM16PR Introduction
Digicom SpA
1. INTRODUCTION
1.1. PRODUCT FEATURES
The digicom LCM16P is a baseband modem in table top or rack version.
It is possible to use LCM16 modem in systems of dedicated point to point,
multiple point and tandem two or four wire lines.
The line must have metallic continuity.
Do not insert channel amplifiers on the line.
Isitpossible toactivateremote digitalloop(Loop 2 “RDL”)andremote loop
3 for tandem configuration in accordance with CCITT V.54 standard.
It supports both asynchronous and synchronous communication modes.
DTE interface speed is from 225 up to 19200 bit/s, with a set of intermediate
speeds for the asynchronous mode.
Modulation and demodulation, synchronous to asynchronous conversion,
interfacesignaldelay,loopsandtime-outsareimplementedbyanewintegrated
ASIC circuit.
The LCM16P was designed in accordance with the Telecommunication
standard Nr. 687.
The modemrespects the normativeEN60950, EN41003 (safety standards)
and EN55022 EN50082-1 (electromagnetic compatibility standards). It
complies with V.24, V.28, and V54 CCITT recommendations and with
ISO2110 standard.
1.2. TECHNICAL CHARACTERISTICS
1.2.1. DTE-DCE digital interface
DTE(DataTerminalEquipment)isthedevice inwhichdata aregeneratedand used.
DCE (Data Circuit Terminating Equipment) is the device in which data are
converted from digital to analog and vice versa.
DTE-DCE interface data signal table
CCITT V28 signal level -3 ÷ -25 V; +3 ÷ +25 V
Binarydenomination BIT 1; BIT 0
Data type MARK (MK); SPACE (SP)
Asynchronousbit STOP (Z); START (A)
Control signal state PAUSE (OFF); WORK (ON)

1.2
LCM16P/LCM16PR Introduction
Digicom SpA
1.2.2. Data input
Synchronous mode operation speed
19200, 14400, 9600, 7200, 4800, 3600, 2400,
1800, 1200, 900, 600, 450, 300, 225 bit/s. It is
possible to change speed by the internal dip
switches.
Asynchronous mode operation speed
19200, 14400, 9600, 7200, 4800, 3600, 2400,
1800, 1200, 900, 600, 450, 300, 225 bit/s, with
extension to the following speeds:
Predisposition Minimumvalue Maximum value
300 292,5 (297,5) 301 (305,25)
600 585 (595) 602 (610,5)
1200 1170 (1190) 1204 (1221)
2400 2340 (2380) 2408 (2442)
4800 4680 (4760) 4816 (4884)
9600 9360 (9520) 9632 (9768)
19200 18720 (19040) 19264 (19536)
(Between parenthesis the extension value)
Type of characters no limit; the modem is transparent to the data
comingthrough.
Interface connector 25 leads female cannon with contacts in
accordance with ISO 2110 standard and CCITT
V24 recommendation.

1.3
LCM16P/LCM16PR Introduction
Digicom SpA
Cont. Circuit Direction Mnem. Description
Conn. V24 RS232 DTE-LCM16 Abbrev.
1 - AA <----> PG Earth protection
2 103 BA -----> TD Transmission data
3 104 BB <----- RD Received data
4 105 CA -----> RTS Request to send
5 106 CB <----- CTS Clear to send
6 107 CC <----- DSR Data set Ready
7 102 AB <----> SG Ground
8 109 CF <----- DCD Data carrier detect
9 - - <----- - + 12 volt
10 - - <----- - - 12 volt
11
12
13
14
15 114 dB <----- TC Transmission Clock
16
17 115 DD <----- RC Receiver Clock
18 141 CN -----> L3 Local analog loopback
application(CCITTLOOP3)
19
20 108.2 CD -----> DTR Data terminal ready
21 140 CF -----> RDL Local digital loopback
application (CCITT LOOP
2LOCAL)
22 125 CE <----- - 12 volt
23
24 113 From -----> ETC External transmission clock
25 142 - <----- TI Active Loop
NOTE: 1, 11, 12, 13, 14, 16, 19, 23 pins are not connected.
Tab.: 1.1. CCITT V24 INTERFACE SIGNALS USED IN LCM16P AND
LCM16/PR MODEMS

1.4
LCM16P/LCM16PR Introduction
Digicom SpA
1.2.3. Clock signal characteristics
(Only for synchronous mode operation)
Signal type Squarewavewithnegativeedgeonthecenterof
data bit. Data change on the positive edge.
Frequency Equaltoselectedspeed.Ithasaprecisionof±50
ppm in the range of above-mentioned tempera-
ture.Themodemacceptsanexternalclocksource
with a 1,5% tolerance.
1.2.3. RTS/ CTS circuits
Delay time The delay time change in accordance with the
speed and it is programmable for 0, 16, 32, 64,
128,256and 512 bit/time according to the chart
1.2:
Delay times (msec)
Speed 16 bits 32 bits 64 bits 128 bits 256 bits 512 bits
Bit/s time time time time time time
300 53 106 212 424 848 1696
600 26 53 106 212 424 848
1200 13 26 53 106 212 424
2400 6,6 13 26 53 106 212
4800 3,3 6,6 13 26 53 106
9600 1,6 3,3 6,6 13 26 53
19200 0,83 1,6 3,3 6,6 13 26
The tolerance of values in the table is ±7%.
Tab.: 1.2. DELAY TIMES RTS/CTS

1.5
LCM16P/LCM16PR Introduction
Digicom SpA
1.2.4. Asynchronous Mode
As described in the following table, it is possible to set the number of data,
stop, and start bits by means of the dip switches:
START bit DATA bit STOP bit
161
171
181
191
1.2.5. Analog Interface: transmission line
Impedance 600 ohm or 150 ohm selected through jumpers.
Itispossibletoputthedeviceinhighimpedance
condition, setting the C105 circuit OFF
TransmissionLevel -12 dBm, -6 dBm, 0 dBm or +6 dBm selected
through jumpers.
Transmission signal type Filtered square wave.
Modulation Differential Bi-fase with two adaptable levels
eitherintheEuropeanstandardorintheAmerican
one (CCITT V.1 and CCITT V.1 inverted)
Carrier level with C105 OFF < 60 dBm.
Equalizer Statistic type, enabled by a jumper, optimized
for the following speeds: 1200, 2400, 4800,
9600, 19200 bit/s or 900, 1800, 3600, 7200,
14400 bit/s.
1.2.6. Analog Interface: receive line
Impedance 600 ohm or 150 ohm selected through jumpers.
Itispossibletoputthedeviceinhighimpedance
conditions.
Maximum receiver level +6 dBm.

1.6
LCM16P/LCM16PR Introduction
Digicom SpA
C109 (DCD) Threshold -40dBmor-30dBm,selectedthroughajumper.
Equalizer Statistic type, enabled by a jumper, optimized
for the following speeds: 1200, 2400, 4800,
9600, 19200 bit/s or 900, 1800, 3600, 7200,
14400 bit/s.
1.2.7. Receive time base (synchronous mode only)
Signal type Squarewavewithnegativeedgeonthecenterof
data bit. Data change on the positive edge.
Frequency Equaltothe transmission one and synchronized
with the remote transmitter.
1.2.8. C109 Circuit
Carrier sense circuit It consists of a digital filter, in order to obtain a
low frequency noise high immunity.
Delay time It depends on the speed.
The ON-OFF transition lasts 17 bit/ time.
The OFF-ON transition lasts 12 bit/ time.
Look at the chart 1.3:
SPEED bit/ s ON/ OFF ms OFF/ ON ms
300 56,6 40
600 28,3 20
1200 14,2 10
2400 7,1 5
4800 3,5 2,5
9600 1,77 1,25
19200 0,88 0,625
Tab.: 1.3. DCD DELAY TIME.

1.7
LCM16P/LCM16PR Introduction
Digicom SpA
1.2.9. Tests
Available Loops Allloopscanberuneitherfromtheuserinterface
or from pushing buttons on the frontal panel.
The loop functions are available for point to point, multi-point and tandem
networks.
Test Enable In local loop 3 and remote loop 2, a push of the
test button allows to send data (BERT 511) to
verify the correct functionality of the net.
1.2.10. Connection distance
Without equalizer Maximum distances with a 6/10 mm line.
SPEED bit/ s DISTANCE Km
300 33
600 29
1200 25
2400 18
4800 12
9600 8
19200 4
Tab.: 1.4. CONNECTION DISTANCE WITHOUT THE EQUALIZER
With equalizer Maximum distance with a 6/10 mm line
SPEED bit/ s DISTANCE Km
300 33
600 33
1200 33
2400 30
4800 24
9600 15
19200 12
Tab.: 1.5. CONNECTION DISTANCES WITH EQUALIZER

1.8
LCM16P/LCM16PR Introduction
Digicom SpA
1.2.11. Line connection
The line is connected thorough a RJ11 connector.
In a two-wire connection, it is mandatory to use the receiver pins (RX).
1.2.12. DTE connection
Standardfemale25contactconnector inaccordancewithISO 2110standard.
1.3. FUNCTIONAL BLOCK DIAGRAM
Look at the schematics indicated in figure 1.1.
Datapump
Microprocessor
Line interface
RS232 interface
Power supply
Loop circuits
1.3.1. Datapump
TheASICchipimplementsallthefunctionsoflinemodulation/demodulation,
transforming the DTE data in a modulated signal.
Itmountsanintegratedasynchronoustosynchronousconverterthattransforms
the asynchronous data from the DTE in synchronous data to the line.
Inasynchronousoperation,thecarrierisalwaysderivedfromtheinternaltime
base.
In asynchronous mode, the as/sync converter is active and the clock from
interface (C114 and C115) are removed.
The modulation code is the same for asynchronous and synchronous mode.
In synchronous mode, it is possible to use as carrier either the transmission
time base or that derived from the automatic speed recognition.
1.3.2. Microprocessor
The microprocessor checks the datapump and reads the configuration
dipswitches and the buttons.
It lights on the leds and checks the interface signals, implementing all the
functions necessary to the correct operations of the apparatus.

1.9
LCM16P/LCM16PR Introduction
Digicom SpA
1.3.3. Line Interface
Beforebeingsentinline,themodulatedsignalis“shaped”andfilteredinorder
to limit the emitted spectrum band.
The telephonic line is coupled using two transformers that guarantee a
1500 Volt isolation between the line leads and the internal circuits.
To compensate the jitters introduced by the line it is possible to insert a
compromise equalizer either on the transmission or on the receive circuits.
The analog signal received from the line is filtered to get a good signal/noise
ratio.
The modem mounts a protection device to shunt down external high-energy
phenomena.
1.3.4. RS 232 Interface
The interface signals coming from DTE are converted to TTL level by the
receivers.
The interface signals coming from DCE are converted to V24 level by the
drivers.
Thedriversaredirectlyconnectedtothedatapumpandtothemicroprocessor.
1.3.5. Power supply circuit
The power supply transforms the AC high voltage from the mains in DC
voltage levels (+5V, 12V).
1.3.6. Loop circuits
Thebuttonson the frontal panel allow the activation of the analog and digital
loopbacks, local or remote LOOP3 and LOOP 2 in accordance with the
CCITT V.54 recommendation.
When line loop (loop 3) is ON, the transmission and receive circuits are
isolated from the line.
When interface loop (loop 2) is ON, the input circuits are isolated from DTE
while the output ones are forced to OFF.
The C142 circuit ON indicates that a loop test is active.

1.10
LCM16P/LCM16PR Introduction
Digicom SpA
JA
INTERFACE CIRCUIT
INTERFACE LOOP
MODULATOR
C105/C106 DELAY
DEMODULATOR
CARRIER
DETECTOR
LINE LOOP
TX
R
X
Fig.: 1.1. FUNCTIONAL BLOCK
DIAGRAM

1.11
LCM16P/LCM16PR Introduction
Digicom SpA
Fig.: 1.2. MODULATION WAVEFORMS
1.4. TRANSMISSION CIRCUIT
1.4.1. Digital section
Aninternallogicregulatesthetransitofdatato/fromtheDigicomASIC,then
data transit through the A/S converter.
The ON position of dipswitch DSC3 activates the synchronous mode.
The OFF position of dipswitch DSC3 activates the asynchronous mode.
In synchronous mode the C103 signal is sent directly to the modulator, in
asynchronous mode first it is converted to synchronous (A/S converter) and
then sent to the modulator.
The A/S converter adds the bits necessary to compensate the difference in
speedbetweentheasynchronousdatacomingfromtheDTEandthemodulator
TX time base.
ThemodulatorclockisderivedfromtheinternalC114circuitorfromtheDTE
C113 circuit.
In some cases, the modulator clock is derived from the receiver time base.
Thetransmissionspeedis chosenpredisposingthedipswitchesDSC5-6-7-8.
The DSD 4 dipswitch allows to choose either CCITT V.1 or CCITT V.1
inverted standard (see figure 1.2).
IfDSD7isinOFFpositionthecarrierisalwayspresent,ifitisinONposition
the modem is in controlled carrier (it follows the C105 signal).
C103
C114
SPACE (0) (+12)
TX CLOCK
REVERSE
CCITT V.1
STANDARD
(AMERICAN
STANDARD)
CCITT V.1
STANDARD
(EUROPEAN
STANDARD)
SEGNAL
TRANSMITTED
ON LINE
MARK (1) (-12)

1.12
LCM16P/LCM16PR Introduction
Digicom SpA
It is possible to activate a time out function on the C105 circuit.
The time out function, if active (dip switches DSE 2-3), allows to block the
carrier for a time of 64 or 128 Kbit/ time.
This function is very useful in multi-point nets, where a continuous
communicationfromaperipheralstationtothemasterwouldcauseablockin
communication with all the other stations connected to the net.
Not use this function: in case of point to point or tandem nets, the correct
operation of the net could be compromised.
Thetimeout interventiontimedepends onthespeed andonthe configuration
delay as indicated in the following table.
Speed 64 Kbit/ time 128 Kbit/ time
19200 3,33s 6,66s
9600 6,66s 13,33s
4800 13,33s 26,66s
2400 26,66s 53,33s
1200 53,33s 106,66s
600 106,66s 213,33s
300 213,33s 426,66s
The dipswitches DSD 1-2-3 and DSE 4 serve to force in work conditions the
C105 (RTS) and the C108 (DTR) signals.
The DSD 1-2-3 serve also to select the delay between C105 and C106.
1.4.2. Analog section
The modulated signal is filtered in order to limit the emission spectrum
(<76dBbeyond160 KHz)andmovingthe jumperU4itispossible tochange
the transmission level.
Equalizationcanbe introduced with jumper U9 (2-3 position) to compensate
distortion introduced by the telephone plug.
Ananalogswitchallowstoimplement eithertwowireoperations(jumperU7
in 1-2 position) or four wire operations with impedance controlled by C105
circuit.
Inthisway,thestructureofmultipointnetsishugelysimplifiedbecausethere
is no need of impedance adapter circuits.

1.13
LCM16P/LCM16PR Introduction
Digicom SpA
With C105 ON, the output impedance is 600 or 150 ohm, while with C105
OFF the output impedance has a value higher than 10 Kohm.
The line transformers assure galvanic isolation (1500 Vrms) and adaptation
between balanced line circuits and unbalanced internal circuits.
Jumpers U2 and U8 select two different values of transmission impedance:
150 ohm (for speeds higher or equal to 2400 bit/ s) and 600 ohm (for speeds
lower than 2400 bit/ s).
Two Metal oxide varistors provide protection against high-energy transients
from the net.
1.5. RECEIVER CIRCUIT
1.5.1. Analog section
The telephonic balanced receive line is connected to the transformer through
the jumpers U12 and U15, that select the input impedance value.
The unbalanced signal coming out of the transformer is protected against
overcurrents by a limitation circuit.
It is possible to increase input impedance to a value higher than 10 Kohm
setting the jumper U13 in 2-3 position.
The received signal is amplified, filtered and in case equalized.
Equalizeradaptationisautomaticforspeedsbetween2400bit/sand19200bit/s.
The filter output is squared in order to adapt the analog signal to the digital
input of the demodulator and the carrier detector.
1.5.2. Digital section
The receiver digital section consists of the demodulator, the PLL circuit for
clock recovery and the carrier detector.
The recovered clock is driven to the C115 circuit.
The carrier detector consists of a high-band digital filter and a timing circuit.
The fast carrier detector circuit (DCD fast), when inserted (DSD5 ON),
detectsabsenceoftransitionsonthemodulatedsignalforatimeof1,5bittime
(±0,5). In this case, the C104 circuit is forced to mark.
This function is useful in half-duplex two wire applications.
Thefastcarrierdetectorcaneliminateproblemscausedbyincomingspurious
characters.
The following figure illustrates an example of line micro-interruption, in