In two out of two systems, two processors receive the command and process it for output generation. The output command is compared first and if matches then only output is energised. There are so many systems available world-wide which has different architecture and modules depending upon manufacturer to manufacturer.
Here we are describing the indigenous system developed jointly by RDSO, DOE and IIT, Delhi.
Indigenous system consists of following -
CPU card ( 2 nos.)
Relay read interface card (RI)
Voltage monitor card (VM)
Comparator card (COMP)
Relay driver card (RD)
Panel processor
a) CPU Card
b) Relay read interface card c) Indication driver card
Data logger Maintainer’s terminal
Operator’s panel.
Operators Panel
CPU 1 CPU 2 Read
Interface System Bus
Comparator
Relay Driver Voltage
Monitor
Field Inputs
Field Inputs Panel
Processor
Fig No. - 13
SOLID STATE INTERLOCKING SYSTEM
Empty cardspace RD – 1 RD – 2 RD - 3 RD – 4 RD – 5 RD - 6 Empty cardspace Empty cardspace Empty cardspace Empty strip
EMPTY SPACE
DC-DC CONVERTOR + 10 V +5v 0.75 A
Empty cardspace COMP – 1 COMP – 2 COMP - 3 COMP – 4 COMP – 5 COMP - 6 Empty cardspace Empty cardspace Empty cardspace Empty strip
MULTI OUTPUT DC/DC CONVERTOR
Empty cardspace RICARD– 4 RICARD-1 RICARD-2 PRO-1 PRO-2 VKCARD RICARD-3 RICARD-5 Empty card Empty slot
EMPTY SPACE
MULTI OUTPUT DC/DC CONVERTOR UNIT EMPTY SPACE
Fig No. - 14
Hardware details CPU card
This is the main processing card of the system and uses Intel 8086/8088 microprocessor. There are two type CPU cards in the system. Processing is done independently in each of the two cards. The system follows two out of two logic.
Read Relay interface Card
This card acts as an input interface to the system from the input relays. The input to the system comes from various fields relays like track circuits, point status relays, signal lamp proving relays, button inputs from the operator’s panel and read back of output relays. This card also isolates the system from the field relays circuits. Provision has been kept for testing of malfunctioning of the system in reading the status of the relays. Each card can read 48/64 input relays. Inputs are isolated using opto couplers.
Comparator card
This card is use for executing the two out of two logic.
The main function of the card is to compare the output of the two CPU cards and give appropriate signals to the relay driver card. Each card caters 8 channels.
Relay driver card
This card acts as an output interface of the system to the field gear controlling relays for points, signals, level crossing, crank handles etc.
are driven by this card. Each card can drive 8/12 relays. In order to isolate electronic circuitry from field equipment, transformer isolation is provided.
In new design relay driver card incorporate comparator card function itself.
Voltage monitor card
The purpose of this card is to monitor various voltage levels in the system. There are 4 Vcc supplies in the system. Change in the operating voltage of the ICs can severely affect the performance of the system. VM card detects any deviation from the allowed safe operating condition. In case of any fault in the system, SSI is brought to a safe shut down by switching off shut down relay thereby withdrawing power from relay driver output.
Software details
The Solid State interlocking consists following:
a) System software is universal and independent of yard layout.
b) Yard data derived from the locking table /
software can be broadly divided into following parts.
Input Read Module
This part of the software reads the input information coming from the interface relays and operating panel.
After proper debouncing, the data is stored in the memory.
Panel Processor module
This part of the software reads the panel command coming from the operating panel and decides the action to be taken for these commands, e.g. Route setting, point operation etc.
Route controller module
This part of the software receives commands from the panel processor and decides the action to be taken for these commands, e.g. route setting, point operation etc.
Signal controller module
This part of the software receives commands from the route controller for the signal clearance. It checks the signal aspect chart, condition of the signal ahead and decides the aspect for the particular signal. Depending on the decision taken, command for picking up the aspect control relays viz., HR, HHR, DR is given by this software. This part of the software is also responsible for checking the reconciled status of the
signal viz-a-viz last command given for signal clearance.
Point and Slot Controller Module
This part of the software accepts the commands coming from the panel processor as well as from the route controller (in case of automatic route setting facility), examines whether the point operation is permitted by the interlocking and issues command for picking up of the point operation relays i.e. WNR/WRR.
Track locking of the point is also checked. This is also responsible for logical locking of the point in the route and makes the reconciled status of the point viz last command given to the routine. The controlling relays WNR/WRR are energised only for the required time and after setting of the point these relays are de-energised.
Ground frames, crank handles and level crossings are also controlled by this routine.
Supervisory Routine Module
In this hardware, two microprocessors have been used for safety reasons. The supervisory routine ensures safety of operation by self-checking of the CPUs and other associated hardware. CPU self-checks include RAM/ROM check. The other hardware is checked for proper addressing / accessing of the data and correctness of the data. In case of a major failure is detected in the CPU / associated hardware, safe shutdown of the whole
display panel, so that the maintainer can take up corrective action such as replacement of a card.
Thereafter, the system can be re-started after rectifying the fault and pressing the reset and restart button.
Counter have been provided for registering resetting operations.
7.3 Two out of Three SSI system