Dynamix RC 903-V35FE1 User manual

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RC C 9 90 03 3- -V V3 35 5F FE E1 1
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V. .3 35 5 t to o F Fr ra ac ct ti io on na al l E E1 1 I In nt te er rf fa ac ce e
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User Manual

1. Cautions
Warning
. Only trained and qualified personnel should be
allowed to install, replace or service this equipment.
RC903-V35FE1 provides Synchronous Digital Interface
complying with the ITU standard. Before power on, the V.35
cable must be well connected. It is strictly forbidden to
hot-swap V.35 cable when the converter and the equipment
connected by V.35 cable are both power on.
RC903-V35FE1 is integrated equipment. Move carefully and do
not disassemble or mend it without the guidance of Dynamix
technical engineer with the anti-static procedures.
The equipment must be grounded. Do not disassemble the
equipment by yourself. It may cause unrecoverable damage.
Dynamix will not be responsible for the damage by this.
1

Contents
1. Cautions..................................................................................................................... 1
2. Overview.................................................................................................................... 3
2.1. Introduction............................................................................................................. 3
2.2. Main feathers:......................................................................................................... 3
2.3. Equipment description............................................................................................ 3
3. Parameters ................................................................................................................ 5
3.1. E1 interface: ........................................................................................................... 5
3.2. V.35 interface: ........................................................................................................ 5
3.3. Cable type: ............................................................................................................. 5
3.4. Power consumption:............................................................................................... 5
3.5. Structure:................................................................................................................ 6
3.6. Ambience ............................................................................................................... 6
4. User Manual............................................................................................................... 7
4.1. Front panel ............................................................................................................. 7
4.2. Back panel.............................................................................................................. 9
4.3. Bottom Dip Switches ............................................................................................ 10
4.4. Inside Jump pin definition..................................................................................... 16
4.5. Basic Connection ................................................................................................. 17
5. Equipment installation and Preparation.................................................................... 20
5.1. Installation preparation ......................................................................................... 20
5.2. Cautions when the power is on ............................................................................ 20
5.3. Placement ............................................................................................................ 21
5.4. Test of connection ................................................................................................ 21
6. Troubleshooting ....................................................................................................... 22
7. Appendix.................................................................................................................. 24
Explanation of CBL-V35-M34F/M34M-D cable ............................................................... 24
Explanation of CBL-V35-M34M/M34M-X-D .................................................................... 24
2

2. Overview
2.1. Introduction
RC 903-V35FE1 is an interface converter for V.35 equipment based on E1 network
transmission. With the growing utilization of E1 resources, many data
transmission solutions using E1 link are accepted by users.
RC 903- V35FE1 is standalone equipment, with built-in power supply, and can be
placed on the table. It provides signal conversion between V.35 and fractional E1, and
can be used in pairs or alone. This equipment will not change the data from V.35
interface.
2.2. Main feathers:
1) Provide a V35 synchronous digital DCE interface complying with ITU standard.
2) Provide an E1 interface complying with ITU standard and both 75
Ω (unbalanced BNC
interface) and 120
Ω (balanced RJ-45 interface) are available for our users.
3) Complete E1 line alarm including both local and remote line alarm.
4) Provide local and remote loop-back test function, which can help easily analysis the
bit rate error.
5) Support E1 fractional and transparent frame modes. When it is in the fractional mode,
the time slot can be allocated at will.
6) Provide 3 clock modes: Master clock, Slave clock, and V35 terminal clock.
7) When working in pairs in the fractional mode, the time-slot allocation of the local
equipment can automatically follow that of the remote equipment.
8) Internal bit error test unit can analysis and test the line with various loop-bake modes.
9) In the fractional mode, PCM30 and PCM31 can be chosen and CRC4 function is
self-adaptive.
10) Provide phase adjustment function for the V35 receiving data.
11) Provide fault pass through function: informing the V35 interface of the E1 fault, and
estimating E1 fault on the Router.
12) Use very large scale ASIC chip with low power consumption, four-layer circuit board
design, and high reliability.
2.3. Equipment description
RC903/904-V35FE1series converter includes the following models :
Part number Description
RC903-V35FE1-AC
Standalone , one E1 interface ( 75 Ω unbalanced or 120 Ω
Balanced), one standard V35 DCE interface ( ISO2593 M34
Female), 220VAC
3

RC903-V35FE1-DC
Standalone , one E1 interface ( 75 Ω unbalanced or 120 Ω
Balanced), one standard V35 DCE interface ( ISO2593 M34
Female ) , -48VDC
RC904-V35FE1
Module , one E1 interface(75 Ω unbalanced), one standard V35
DCE interface
, HDB26 male(transform to ISO2953 M34 female
through attached cable
)
RC904-V35FE1-BL
Module, one E1 interface ( 120 Ω balanced, one standard V35 DCE
interface
) HDB26 male ( transform to ISO2953 M34 female through
attached cable
)
The models in shadow of the above table are included in this manual. The equipment in
the above table can be used in pairs or alone.
4

3. Parameters
3.1. E1 interface:
Input impedance: Two 75 Ω ( unbalanced BNC interface) and one 120 Ω
(balanced RJ-45 interface
)
Interface bit rate: 2048Kbps±50ppm
Line code: HDB3
Physical characteristics: Complies with ITU-T G.703
Frame structure: Complies with ITU-T G.704
Pass-through characteristics: Complies with ITU-T G.823
Jitter tolerance: Complies with ITU-T G.823
Functions: Completed link alarm indication, Fault Pass Through
(FPT) and auto-reset
3.2. V.35 interface:
Physical characteristics: Complies with ITU V.35 interface standard
Connector type : ISO2593 female connector (M34 female)
Working mode
: DCE (support cross-connection with other DCE device)
Interface bit rate: V.35 interface bit rate is N×64Kbps(N=1~31
) at E1
fractional pattern;
V.35 interface bit rate is 2048Kbps at E1 transparent
pattern
3.3. Cable type:
When connecting to the BNC interface, it is suggested to use SYV 75-2-2 coaxial cable.
SYV 75-2-1 or SYV 75-1-1 could also be chosen.
When connecting to RJ-45 interface, it is suggested to use 0.6mm (22AWG) twisted pair.
When connecting to DTE equipment such as Router through M34 interface, it is
suggested to use special DTE cable for Router. When the DTE cable is not long enough,
Dynamix can provide CBL-V35-M34F/M34M- D extension cable.
When connecting to other DTE equipment through M34 interface, it is suggested to use
cross-connect cable CBL-V35-M34M/M34M-X-D provided by Dynamix.
3.4. Power consumption:
AC: 220V/50Hz ( input ranges from 165 to 265V )
DC: -48V
( input ranges from -36 to -72V )
+24V
( input ranges from +18 to +36V)
Power consumption: ≤5W
5

3.5. Structure:
Standalone
Dimensions: 120(W)*39(H)*155(D) mm
3.6. Ambience
Operation temperature: 0 ~ 45 °C
Operation humidity: ≤90% (25
°C)
6

4. User Manual
4.1. Front panel
Power Indicator
:
Sketch of the front panel
Power (PWR)
: On: power is working in good condition
Off: Power is off.
V35 interface Indicator
:
TD Green: Flashing: when there is data flow of TD signal (sending data) at the V.35
interface. The Flashing frequency differs with the interface rate of V.35. When it is 64Kbps,
the Flashing frequency is the lowest; when it is 2048Kbps, the Flashing rate is the highest.
Off: there is no data flow of TD signal at the V.35 interface.
RD Green: Flashing: when there is data flow of RD signal (receiving data) at the V.35
interface. The Flashing frequency differs with the interface rate of V.35. When it is 64Kbps,
the Flashing frequency is the lowest; when it is 2048Kbps, the Flashing rate is the highest.
Off: there is no data flow of RD signal at the V.35 interface.
Test status Indicator
:
TEST yellow: On: bit error test function is enabled. In the fractional mode, the local or
remote loop-back function is correctly set. In the transparent mode, the local loop-back
function is correctly set.
Flashing: bit error test function is enabled. In the fractional mode, the
local or remote loop-back function is wrongly set. In the transparent mode, the local
loop-back function is wrongly set.
Off: bit error test function is disabled.
LOOP yellow: On: The loop-back is at the local site.
Flashing: The loop-back is at the opposite site (only effective when the
E1 is fractional)
Off: No loop-back
PAT yellow: On: when receiving pseudo random series from the BERT unit, and there
is no bit error on line.
Off: when receiving pseudo random series from the BERT, but when
there is bit error on line, it goes off for at least 1 second.
Off: Bit error test function is disabled.
7

E1 interface alarm Indicator
:
LOS red: On: loss of receiving signal at local E1;
Flashing: loss of receiving signal at remote E1 (only effective at fractional
mode);
Off: Local and remote signal are normal
AIS red: On: Receiving all ‘1’ AIS alarm at the local E1
Flashing: Receiving all ‘1’ AIS alarm at the remote E1 (only effective at
fractional mode);
Off: Local and remote signal are normal
LOF red: On: Receiving Loss of frame LOF alarm at the local E1 (only effective at
fractional mode);
Flashing: Receiving Loss of frame LOF alarm at the remote E1 (only
effective at fractional mode);
Off: Local and remote signal are normal
LOMF red: On: Receiving Loss of Multi-frame LOMF alarm at the local E1 (only
effective at multi-fractional mode)
Flashing: Receiving Loss of Multi-frame LOMF alarm at the remote E1
(only effective at multi-fractional mode);
Off: Local and remote signal are normal
CV red: On: Receiving code violation CV alarm
Flashing: Receiving code violation CV alarm (only effective at fractional
mode);
Off: Local and remote signal are normal
CRC red: On: Receiving CRC4 check error alarm
Flashing: Receiving CRC4 check error alarm (only effective at fractional
mode);
Off: Local and remote signal are normal
Attention: This equipment supports CRC4 check self-adaptive function. When there
is CRC4 check information in the received E1 signal, the check
function is automatically enabled. The CRC alarm indicator will be
on, only when there is CRC4 fault; when there is no CRC4 check
information in the received E1 signal, the check function is
automatically disabled, and the CRC alarm indicator is disabled.
E1 interface:
BNC coaxial interface: TX, 75
Ω unbalanced signal output
RX, 75
Ω unbalanced signal input
RJ-45 interface: 1, 2 pin, 120
Ω balanced signal output
4, 5 pin, 120
Ω balanced signal input
Attention: The default configuration is BNC coaxial interface effective. If you want to
use the RJ-45 120
Ω interface, the dip converter SW6 on the
bottom should be adjusted.
8

4.2. Back panel
Sketch of the back panel of AC equipment
Sketch of the back panel of DC equipment
Power interface:
AC interface: standard 3 phase AC power supply interface. Please guarantee that it is
correctly grounded.
DC interface: DC ports: -48V, PGND, BGND, Please make sure that PGND is
grounded; BGND is connected to 0V of DC power supply; -48V is
connected to -48V of DC power supply.
V.35 interface:
The left figure shows V.35 interface ISO 2593
connector. Our converter adopts DCE Connector
Face – 34-Pin Female connector, which can be
connected with DTE cable.
The definition of interface is shown below
:
I — Input
; O— Output
Pin name Input/Output Pin number
Chassis Ground — CGND -A
Signal Ground — GND -B
Receive Data (A) — RD(A) OR
Receive Data (B) — RD(B) OT
Receive Timing (A) — RCK(A) OV
Receive Timing (B) — RCK(B) OX
Send Data (A) — TD(A) IP
9

Send Data (B) — TD(B) IS
Send Timing (A) — TCK(A) OY
Send Timing (B) — TCK(B) OAA
Terminal Timing (A) — SCTE(A) IU
Terminal Timing (B) — SCTE(B) IW
Request to Send — RTS IC
Clear to Send — CTS OD
Data Set Ready — DSR OE
Data Carrier Detect — DCD OF
Data Terminal Ready — DTR IH
4.3. Bottom Dip Switches
ON ON DIP
OFF
1 2 3 4 5 6 7 8
There are 6 groups of 8-bit DIP switches. The positions of the six switches are called
SW1, SW2, SW3, SW4, SW5, and SW6. Every switch is like the above figure. OFF is
below, and ON is above.
There is a DIP switches explanation table on the rear board as follows:
V35
Interface
Power supply
Interface
Timeslot configuration switch SW1 to SW4
The ‘√’ means enable, and ‘×’ means disable.
SW1 switch definition (default OFF)
1st
bit 2nd bit 3rd bit 4th bit 5th bit 6th bit 7th bit 8th bit
Definition Frame TS1 TS2 TS3 TS4 TS5 TS6 TS7
10

1st
bit 2nd bit 3rd bit 4th bit 5th bit 6th bit 7th bit 8th bit
Definition Timing
Clock 1
Timing
clock2
TS_FLOW
Time slo
t
follow
BERT
Bit error
test
RX CLK
phase
ALOOP
Local V35
port
loop-back*
DLOOP
Local E1
Line
loop-back*
RLOOP
RemoteE1
Line
loop-back*
ON **√√Negative √√√
OFF **××Positive ×××
format*
ON Fractional √√√√√√√
OFF Transparent ×××××××
SW2 switch definition (default OFF)
1st
bit 2nd bit 3rd bit 4th bit 5th bit 6th bit 7th bit 8th bit
Definition TS8 TS9 TS10 TS11 TS12 TS13 TS14 TS15
ON √√√√√√√√
OFF ××××××××
SW3 switch definition (default OFF)
1st
bit 2nd bit 3rd bit 4th bit 5th bit 6th bit 7th bit 8th bit
Definition TS16* TS17 TS18 TS19 TS20 TS21 TS22 TS23
ON √√√√√√√√
OFF ××××××××
SW4 switch definition (default OFF)
1st
bit 2nd bit 3rd bit 4th bit 5th bit 6th bit 7th bit 8th bit
Definition TS24 TS25 TS26 TS27 TS28 TS29 TS30 TS31
ON √√√√√√√√
OFF ××××××××
Attention:
If SW1-1 is in the transparent mode, TS1 to TS31 switches are not effective.
If SW1-1 is in the fractional mode, TS1 to TS31 switches are effective and cannot be
all OFF. At least one timeslot is enabled, or else it is not fractional.
If SW3-1(TS16) is enabled, the equipment is working under the PCM31 mode.
If SW3-1(TS16) is disabled, the equipment is working under the PCM30 mode.
Function selecting converter SW5:
The ‘√’ means enable, and ‘×’ means disable.
SW5 converter definition
1. 1st and 2nd bit: clock selecting switch Timing1, Timing2 (default all ON)
The clock mode is decided by both the 1st
and 2nd switch, the definition is as follow:
1st
bit 2nd bit Clock mode
11

OFF OFF Master clock (internal timing)
OFF ON
ON OFF
V.35 Terminal clock ( followV.35
interface timing
)
ON ON Slave clock (followE1 line timing)
2. 3rd bit: selecting switch for auto follow function TS-FLOW (default OFF)
3rd bit Timeslot auto follow
function
ON Enable
OFF Disable
To realize the setting of local timeslot bandwidth to follow the remote site, the following
pre-conditions must be guaranteed:
1) This equipment is used point to point in pairs.
2) There is no PCM equipment occupying Sa bit connecting in series in the E1 link
3) The local equipment should be set to the slave clock mode.
After fulfilling the above condition, you can set the auto-follow switch of the local
equipment to ‘ON’ to enable the auto-follow function. The timeslot occupying and
frame mode (PCM30/PCM31) setting of the local equipment will automatically follow
the remote equipment.
3. 4th bit: selecting switch for bit error test function BERT (default OFF)
4th bit Inner bit error test
function
ON Enable
OFF Disable
There is an internal bit error test unit in this equipment. Its main function is to produce
a pseudo random series in the format of 2E15-1-Std, which will be sent to the E1 line.
User could load this series to proper data channel through configuration, and then with
multiple loop-back function, the returned series can be checked by the equipment.
The result will be shown on the PAT indicator on the front panel. When bit error is
detected, the PAT indicator will be off for at least 1 second. If there is no new bit error,
PAT indicator will return to the on status.
If the bit error test function is on, test series will be inserted into the data channel used
by the client. This function can be used both in the fractional and transparent mode.
When this function is in use, business on the V.35 interface will stop.
Attention:
(1) Bit error test function could be combined with multiple loop-back for testing.
When the local V.35 interface loop-back function is not enabled, you can use
coaxial cable to make a loop-back at the E1 interface on the local equipment,
which means testing the local equipment. In this situation, the TEST
indicator is Flashing, the LOOP indicator is OFF, and the PAT indicator is ON,
12

which means that it has receive the correct test bit. If you choose to set the
loop-back of the remote E1 line RLOOP, it means testing the whole process
of signal.
(2) When testing the local E1 loop-back DLOOP, the bit error test function at the
remote equipment and the local E1 loop-back function at the local
equipment DLOOP should be on. It means that the test bit sent by the
remote equipment loops back on the local equipment. At this time, if the
remote and local equipment are both working in the transparent mode, the
TEST indicator at the remote equipment should be Flashing, the LOOP
indicator is off and the PAT indicator is on, which means that it has received
the right test bit; if the remote and local equipment are working in the
fractional mode, the TEST indicator at the remote equipment should be on,
the LOOP indicator is Flashing and the PAT indicator is on, which means
that it has received the right test code.
(3) When the loop-back ALOOP function at the local V.35 interface is enabled,
the local equipment must be working in the Master clock mode or V.35
terminal clock mode, or else, it will not work normally. At this time, the test
code returns to the internal of the equipment for check before it is sent out of
the E1 interface. It means testing some function of the equipment.
4. 5th bit: selecting switch of the received data phase of V.35 RX CLK phase
(default OFF)
5th bit RX CLK phase
ON Negative
OFF Positive
RX CLK phase selecting provides different options according to the relation
between V.35 clock of different brand Router and the data phase When RX CLK
is positive, it passes the test on the V.35 synchronizing WAN interface of Cisco
Router.
RX CLK positive: data is sent to RD signal when the RX CLK clock is at the
negative edge.
RX CLK
RD
RX CLK negative: data is sent to RD signal when the RX CLK clock is at the
positive edge.
RX CLK
RD
Attention: The phase relation of TX CLK and TD is adjusted automatically.
13

Local
Conve
r
te
r
Local
Conve
r
te
r
Remote
Converter
Local
Conve
r
te
r
Re
m
ote
Co
n
ver
t
er
5.6th 7th and 8th bit: selecting switch of the loop-back type (default OFF)
6th
bit 7th bit 8th bit
ON Local V35
interface loop-back
Local E1 line
loop-back
Remote E1 line
loop-back
OFF No loop-back No loop-back No loop-back
The loop-back test function is the assistant function for the user to adjust equipment
and test the link. The client could set the type of loop-back according to different
needs to realize different test functions.
(1) Local V.35 interface loop-back test ALOOP
DTE or V.35 bit
error tester
V.35
E1Channel
As shown in the above figure, user can set the fractional/transparent mode, related clock
mode and bandwidth of the local converter. If the local V.35 loop-back is successful,
LOOP indicator is ON. When the Router connecting to the local equipment is checking the
interface, the loop-back status could be shown. The local V.35 interface loop-back test is
usually used to test whether the connection of V.35 cable is all right, whether the Router
interface has started working, and whether the clock and data phase relation between
Converter and Router is right or not and so on.
(2) Local E1 line loop-back test DLOOP
DTE V.35 E1Channal
V.35 DTE orV.35bit
error tester
As shown in the above figure, user can set the fractional/transparent mode, related
clock mode and bandwidth of the local converter. If the local E1 line loop-back is
successful, the LOOP indicator is ON. When the Router at the remote site is
checking the interface; the loop-back status could be shown. The loop-back test at
the local E1 line is usually used to check whether the V.35 cable at the remote site
is connected correctly or not, the Router interface at the remote site has started
working or not, and the clock and data phase relation between the Converter and
Router at the remote site is right or not and so no.
(3) E1 line loop-back at the remote site RLOOP
DTEorV.35 Bit
error Tester V.35 E1Channel
To realize the E1 line loop-back at the remote site, the following pre-conditions must
be guaranteed:
1) This equipment is used point to point in pairs.
14

5th bit 6th bit 7th bit 8th bit 5th bit 6th bit 7th bit 8th bit
ON ON ON ON
OFF OFF OFF OFF
2) There is no PCM equipment occupying Sa bit connecting in series in the E1 link
3) The local and remote equipment should not all be set to the transparent mode.
As shown in the above figure, if the above conditioned is fulfilled, the related clock
mode and bandwidth could be set. If the connection of E1 is correct, the local LOOP
indicator is Flashing, which means that the remote E1 interface loop-back is
successful. When the Router at the local site is checking the interface, the
loop-back status could be shown.
 Switch for function selection SW6 :
SW6 switch definition:
1st
bit 2nd bit 3rd bit 4th bit 5th bit 6th bit 7th bit 8th bit
Definition Fault
pass
through
Reserved Reserved Reserved Selection of the type of E1interface
impedance
ON Enable
OFF Disable Normal Normal Normal
E1 interface type - user could set
according to practical application. The
default is 75
Ω BNC.
1. 1st bit: Selecting switch for fault pass through (default OFF)
1st bit Fault pass through
ON Enable
OFF Disable
When the fault pass through function is enabled, the E1 sending and receiving side alarm
is transmitted to DCD and CTS signal of the V.35 interface. When the fault pass through
function is disabled, the DCD and CTS signal of the V.35 interface is always effective.
If there is local alarm on the Converter, it means that there is fault at the E1 receiving side,
therefore the DCD signal at the V.35 interface will be closed, and there is reflection at the
DTE equipment.
If there is remote alarm on the Converter, it means that there is fault at the E1 sending
side, therefore the CTS signal at the V.35 interface will be closed, and there is reflection at
the DTE equipment.
The DSR signal of this equipment is effective after power on.
2. 2nd 3rd and 4th bit: Reserved switch (default OFF)
These converters are reserved configuration switches for test. When the
equipment is working, they should all be in the OFF status.
3. 5th 6th 7th and 8th bit: selecting switch for the type of E1 interface
impedance. (Default ON ON ON OFF)
75
Ω BNC unbalance interface effective 120 Ω RJ-45balanced interface
effective
15

5th bit: sending side ‘TX-grounded;
6th
bit: receiving side ‘RX-grounded;
7th
bit: impedance adjustment at the receiving side
8th
bit: impedance adjustment at the sending side
Attention: Set according the above table, or else the E1 interface will be abnormal.
4.4. Inside Jump pin definition
When the user want to adjust the internal jump pin, please do it under the guidance or
agreement of Dynamix technical engineer. Usually it is not necessary; unless it is in
sever environment or disturbance.
After opening the case, you can see two groups of Jump pin (JP2 and JP3) on the
upper layer of the circuit board. Its position, order of pin and default configuration is as
follow:
 Definition of Jump pin:
JP2
1:PGND protection ground
2:BNC_GND BNC screened layer
3:GND working ground
The default setting is 1-2 pins short-circuited.
JP3
1:PGND protection ground
2:GND working ground
3:NC No definition
The default setting is 1-2 pins short-circuited.
16

4.5. Basic Connection
The topological figures here are just for reference, users can design it according to
practical application. The figures only take RC903-V35FE1 standalone converter as
an example.
1) Point-to-point fractional E1 mode in “Master clock — Slave clock”
structure
(Master clock) (Slave clock)
As the above figure shows, when connecting Routers or other equipment with V.35
interface using point-to-point pattern, Routers are required to work at DTE mode. For the
convenience of installation and preparation, users can set Master Clock Mode in local
converter and Slave Clock Mode in remote converter, and the clock source should be in
local converter.
17

When using “Master Clock — Slave Clock” connection structure, if DXC and MUX
devices are connected in series in E1 link, then DXC, MUX and remote converter should
be at Slave Clock Mode (following E1 link clock).
2) Point-to-point fractional E1 mode in “Terminal clock — Slave clock”
structure
(Terminal clock) (Slave clock)
(Clock source)
When remote DTE equipment has to follow the clock phase of local DTE equipment,
which is to say, TX CLOCK of local DTE is internal clock source, users can set Terminal
Clock Mode in local converter, and Slave Clock Mode in remote converter, and must
configure clock frequency at V.35 interface of local DTE equipment.
When using “Terminal clock — Slave clock” connection structure, if DXC and MUX
devices are connected in series in E1 link, then DXC, MUX and remote converter should
be at Slave Clock Mode (following E1 link clock).
3) Point-to-point fractional E1 mode in “Slave clock — Slave clock” structure
(Clock source)
(Slave clock) (Slave clock)
When using Slave Clock Mode at both sides, it is required to ensure that the clock source
is provided by DXC, MUX or other PCM fractional E1 equipment in the E1 link, and there
is only one clock source in the E1 link.
4) Extended connection type
In this connection type, the converter is not used in pairs, but connected with equipment of
18

other manufactures.
ADM
If Routers with E1 interface are used at remote side, users are required to first confirm all
the parameters of E1 link, such as fractional/transparent E1, PCM30/31, CRC
enable/disable, clock relations, bandwidth distribution and time slot usage etc. If any one
of them does not match the setting of the converter, there will be problems in connection.
In this case, if devices at both ends work in fractional E1 mode, usually the clock relation
is easily ignored. It is suggested that first make sure which device the clock source is on,
then devices at other end should follow the clock on the E1 link.
19