Electronics Unit Flashcards
Electronics Unit Overview
The EU is the controller of the VOBC and controls and monitors functions for the trainside CBTC equipment. It provides the ATP and ATO functions. It communicates with the VCC.
Positioning Computer
The Positioning Computer module is responsible for the determination of train velocity and fine positioning relative to tag crossovers and tag boundaries. A wheel wear compensation switch compensates for varying wheel diameters.
On-board telegram Processor (OTP)
The two OTP modules provide the interface between the VOBC CPUs system and the vehicle subsystems (TCMS/TIU/VCC).
Temporary Latch A
The TLA temporarily stores data output from each internal data bus for the corresponding output port (OTPORT).
Interrupt Controller
The INTC module provides a means of synchronisation and storage for the CPU interrupt requests. These requests are generated in other system parts.
Interrupt types (7)
Power on TIU incoming telegram 4ms Timer pulse Incoming WTP telegram TCMS Incoming telegram Application Cycle Data Exchange and cross comparison
Clock Generator
The real time clock (RTC) module produces a control clock signal every 66.67ms. It synchronises all data input to the system and is wired to the INTC to issue a common interrupt request to both CPUs.
Force Actuated Relay
The FAR modules contain four FARs used for controlling vital outputs and are activated from an OTPORT module.
Solid State Output Relay
The SSO modules are used for non-vital outputs. Each SSO has eight solid state relays which are activated by the otport.
Pulse Width Modulator
The PWM module accepts digital data from the EU processors and modulates a pulse width signal proportional to the propulsion/braking effort required by the VOBC.
Interval Measurement Control
The IMC module overrides everything and performs an emergency brake when commanded. They activate the EB relay in the IRU.
