Smartlock 400 SSI Comparison
Smartlock 400 – SSI Comparison
This brochure lists the major similarities and
differences between a Solid State interlocking (SSI)
and Smartlock 400 (SML 400) system.
It is provided as a source of
information to assist those already
familiar with UK SSI architecture in
their understanding of the features
of Smartlock 400.
Single SSI with Signaller’s
Entrance/Exit (NX) Panel
& Local Trackside
Communications
The simplest SSI architecture is
illustrated in Figure 1. This shows
a typical small scheme, with the
signaller and SSI interlocking
co-located and the trackside
area of control in close proximity,
allowing the trackside equipment
to be controlled via dual trackside
data links using Data Link Modules
located inside the SSI cubicle.
The trackside data links may be
diversely routed to counter the threat
of simultaneous malfunction of both
links owing to a common cause.
Smartlock 400 – SSI Comparison
CONTROL ROOM
NX PANEL
TRAIN DESCRIBER
PMUX
EQUIPMENT ROOM
SSI
PPMs
MPM 1
MPM 2
MPM 3
TECH TERM
Diag M
DLMs
TFM
Network
Figure 1 Single SSI with Signaller’s Entrance/Exit (NX) Panel & Local Trackside Communications.
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CONTROL ROOM
NX PANEL
TRAIN DESCRIBER
PMUX
EQUIPMENT ROOM
IMnet
I/O
Channel
1
CC1
I/O
Channel
2
CC2
2003
CC3
F/E
N
F/E
R
GW
A
GW
B
Support System
Maintenance
Signalling Technician
Incident Investigation
DLMs
TFM
Network
Figure 2 Smartlock 400 with NX Panel & Local Trackside Communications.
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Smartlock 400 – SSI Comparison
Smartlock 400 with NX Panel & Local Trackside Communications
SML400 architecture for a scheme such as
which are then passed to the Gateway (G/W)
that in Figure 1, is shown in Figure 2. A
Front End. The front end returns its current
Central Interlocking, employing Alstom’s 2
image of the TFM replies to the interlocking.
out of 3 (2oo3) platform with standard
The front end executes continuous cyclic
operating system and interlocking software,
control/polls of the TFMs, using the most
is configured with additional, UK specific, NX
Panel software. The standard interlocking
recently received information from the
software performs the logic equivalent to that
interlocking and recording the TFM replies to
performed in SSI Multi-Processor Modules
maintain an up–to-date image of trackside
(MPMs). The NX Panel software provides
states. The gateway front end manages the
panel display functions equivalent to those in
timing of the TFM Data Link protocol. The
a Panel Processor Module (PPM), including
remote gateways (which for a simple scheme
Panel Multiplexer (PMUX) and Train Describer
like this are co-located) manage just one
(TD) interfaces.
TFM poll/reply at a time, being slave to the
Gateway front end, but master for the TFMs.
A single central interlocking can replace six
SSIs fitted with PMUX and TD interfaces.
The “Support System” is provided instead of
Further Smartlock central interlockings can
the SSI technician’s terminal. This offers
be added to the same scheme. These
improved functionality and is implemented
communicate with each other over a new
with modern supportable technology,
interface that is faster than the SSI’s Internal
compliant to current standards.
Data Link (IDL).
Access to functions for:Identical trackside data links and TFMs are
employed, but instead of being driven by
trackside comms processors in the MPMs,
they are driven via a Trackside Functional
Module Gateway communications system
(TFMGW).
• System maintenance diagnostics
• Application and removal of signalling
controls such as route bars
• Logged data investigation.
Redundant hardware is provided to improve
The interlocking evaluates a complete set of
availability and provide access points in
trackside controls in one “evaluation cycle”,
diverse locations for the different user types.
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Multiple SSI with Visual Display Unit (VDU)
Signalling Control System & Remote
Trackside Communications
Figure 3 shows a typical SSI arrangement
used where a VDU based signalling control
system (ICONIS, MCS, IECC…) is used to
control multiple SSIs whose trackside
equipment is sufficiently remote to require
access via Long Distance Terminals (LDTs).
LDTs may also be used where the trackside
equipment is close, but the diverse data link
is fed from the remote end to improve
availability. Access to the remote end is
often most economically achieved via a
telecom network.
The LDT is
designed to
operate via a
network offering
a G703 standard
interface.
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Smartlock 400 – SSI Comparison
CONTROL ROOM
WORKSTATION
WORKSTATION
WORKSTATION
x2
EQUIPMENT ROOM
SSI A
SSI B
PPMs
PPMs
MPM 1
MPM 2
MPM 3
MPM 1
MPM 2
MPM 3
TECH TERM
Diag M
DLM
LDT
Diag M
DLM
DLM
LDT
DLM
IDLA
IDLB
D&I G703
Interfaces
ACTIVE CABINET 1
PCM
Network
D&I G703
Interfaces
LDT
DLM
ACTIVE CABINET 2
ACTIVE CABINET 3
D&I G703
Interfaces
D&I G703
Interfaces
LDT
DLM/TFM
Network
DLM
LDT
DLM
LDT
DLM/TFM
Network
Figure 3 Multiple SSI with Visual Display Unit (VDU) Signalling Control System & Remote.
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DLM
CONTROL ROOM
WORKSTATION
WORKSTATION
WORKSTATION
EQUIPMENT ROOM
Cnet
IMnet
SERVER
I/O
Channel
1
CC1
I/O
Channel
2
CC2
F/E
N
CC3
A1
2003
F/E
R
B1
A2
Support System
Maintenance
Signalling Technician
Incident Investigation
B2
N/W
Interfaces
Standard Network
(e.g. SDH, PDH...)
ACTIVE CABINET 1
ACTIVE CABINET 2
ACTIVE CABINET 3
N/W
Interfaces
N/W
Interfaces
N/W
Interfaces
GW
A1
DLM
GW
B1
DLM/TFM
Network
DLM
GW
A2
DLM
GW
B2
DLM/TFM
Network
DLM
Figure 4 Smartlock 400 with VDU Signalling Control System & Remote Trackside Communications.
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Smartlock 400 – SSI Comparison
Smartlock 400 with VDU Signalling Control System & Remote
Trackside Communications
The Smartlock 400 architecture for a larger
scheme is illustrated in Figure 4. Only one
interlocking is shown as a single Smartlock
400 CIXL is capable of managing the
equivalent of several SSIs, making links
equivalent to the SSI IDL only
necessary for the largest schemes.
The networks shown are duplicated
for availability.
The TFM gateway front end and
remote gateway components can be
distributed across a standard
telecomm network as shown.
Each TFM gateway front end can
manage 2 fully populated TDLs
(maximum 3 if only partially populated)
i.e. 4 remote gateways (maximum 6).
A Smartlock 400 interlocking can
control several TFM gateway front ends.
If the gateways are co-located with
the central interlocking, existing LDT
links may be used to communicate to
the trackside.
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Smartlock 400 with Smart I/O
Architecture
A later release of Smartlock 400 offers a
replacement for DLM and TFM networks
and the TFM gateway, allowing the CIXL to
address a much greater number of I/O
points at increased speed. It will enable
migration of an existing trackside network to
Mode 2 (Warm) – Enforced where mode 1 is
not enforced (not a lengthy power out and at
most one difference in the technician’s
controls), but significant differences in some
flag memory states. Flag states over which
there are differences are forced to the most
restrictive state, but the interlocking comes
on-line automatically after a time delay.
this architecture by replacing the track data
Mode 3 – Permitted where neither of the
link cable and DLMs, whilst retaining the
other modes is enforced (few differences in
existing TFMs. New trackside networks will
only certain flag memories permitted). The
benefit from a TFM equivalent with improved
interlocking continues without interruption,
remote diagnostics.
forcing those flag memories where there
were disagreements to the restrictive state.
Functionality
Smartlock 400 permits an equivalent to
Start Up
modes 1 and 2. It protects from power
outage and permits hot swap board
SSI has 3 modes of start up:-
replacement.
Mode 1 (Cold) – Enforced when the system
detects extended power out or more than
Normal Operating Mode
one disagreement between the preserved
SML 400 Interlocking functionality will be
states of technician’s controls. This mode
almost identical to conventional SSI, the only
requires confirmation from a technician to
behaviour variations when compared to SSI
start up – allowing the technician to re-apply
being response times (within permitted limits).
controls having consulted a paper log.
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Smartlock 400 – SSI Comparison
Performance
SSI introduces an average cross boundary
route setting delay of 4 seconds, with a
maximum of 8 seconds (excluding point
operation times). These times increase to 8
seconds and 16 seconds respectively if a
route crosses 2 interlocking boundaries.
Smartlock 400’s ability to manage larger areas
avoids such delays and permits boundaries to
be chosen at less time-critical locations.
A Smartlock 400 system can cover an area
equivalent to 6 panel SSIs, or 8 if controlled
by a VDU based system. This number will
increase with the future introduction of
Smart I/O.
Maintenance Issues
Diagnostic
Smartlock 400 diagnostic information is
made available to maintainers remote from
the interlocking cubicle via standard
communications networks.
On-line Repair
Similar to SSI, replacement of failed units in
the central interlocking cubicle can be effected
without taking the interlocking off-line.
Data Recording
It is possible to perform a ‘live’ search back
through 28 days of recorded history of the
system’s behaviour and copy parts of the
history onto media, for offline analysis, such
Key response times between an SSI and
that it cannot be altered and will survive 5
SML400 interlocking are similar. For SML400, years storage without degradation.
the average time to revert a signal to danger
The SSI log is typically shorter than 28 days.
in the event of a change of trackside input
state is less than 2 seconds. The maximum
time is less than 4 seconds.
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System Configuration
The main differences to an SSI scheme are
summarised below.
The initial stages of the process for configuring
the central interlocking data is the same as
those used for SSI. SSI
source files are initially
prepared using the
current automated tool,
then completed using a
text editor tools to add
customised data.
insertion into the interlocking is a set of 3
USB memory devices (rather than the
EPROMs used for SSI). The contents of the
USB devices are diversified, forcing
differences in software execution between
The desk check is soon
to be assisted by a PC
simulation of the logic
at this time, rather than
by visual inspection
alone – as is currently
the case for SSI.
Pre-processing of the original SSI source
files expands some of the “special”
constructs into multiple standard
constructs. A compilation stage follows to
produce data that can be executed by the
Smartlock 400 system.
Similar to SSI, a diverse de-compiler is used
to provide verification that the compiler has
not introduced errors.
The physical media onto which the whole
interlocking application is prepared for
channels to improve safety. Unlike SSI, the
USB devices contain the fixed interlocking
and operating system software, as well as
the scheme specific data.
Automated testing on a target platform is
provided to catch errors early and boost
confidence following changes.
Formal principles testing is undertaken on a
target system with external simulation,
rather than the Design Work Station (DWS)
as for SSI.
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Smartlock 400 – SSI Comparison
As with SSI, a separate mechanism is
provided to check the interlocking identity
and version number, to prevent incorrect or
old data, or data for the wrong scheme from
being used by mistake.
The TFM Gateway components must also
be configured. There is no directly equivalent
process for this with SSI, which employs
connector looping to set scheme specific
addresses on the LDTs.
Tool support is provided in the future for
scheme design: Scheme Plans, Control
Tables, CAD Design for build and trackside
installation, linked to the interlocking
configuration data.
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RAMS Performance
The main improvements in availability are
driven by improved, remote diagnostic
facilities to speed mean time to repair of
failed components.
Borehamwood Industrial Park
Rowley Lane Borehamwood
Hertfordshire
WD6 5PZ
Telephone: +44 (0) 20 8953 9922
Facsimile: +44 (0) 20 8905 1085
www.signallingsolutions.com
Prices are correct at the time of publication. Signalling Solutions Limited reserve the right to change specifications and prices.
Issue 3 August 2010
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Signalling Solutions Limited