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Description

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Product Overview

The Trusted® Communications Interface (CI) is an intelligent module that provides a range of communication services for the Trusted Controller, minimising communication loading of the Triple Modular Redundant (TMR) Processor. A user-configurable module, the CI can support multiple communication media. Up to four Communications Interfaces (CIs) can be supported by a Trusted System.

Features:

• Trusted Operating System. • Dual Ethernet and four serial ports. • Support for a wide range of communication protocols. • Secure, dependable communications via high performance communications links. • Modbus Slave. • Optional Modbus Master (with T812X Trusted Processor Interface Adapter). • Optional Sequence Of Events (SOE) Over Modbus. • Front Panel serial diagnostic port, fault and status indicators.

1.3. Overview

The Trusted CI provides the Trusted System with an intelligent Communications Interface, acting as a relay between the Processor, other Trusted Systems, the Engineering Workstation and third-party equipment.

1.3.1. Hardware

The module has a Motorola Power PC Processor. Bootstrap software is stored on Erasable Programmable Read Only Memory (EPROM). Operational firmware is stored in flash memory and may be upgraded via the Front Panel Port. The Trusted Operating System is used on both the TMR Processor and CI. The real time kernel is a high speed, high functionality kernel made for fault tolerant distributed systems. The kernel provides basic services (such as memory management) and interference free software environments. A module watchdog monitors processor operation and the power supply unit (PSU) output voltages. The module is supplied with a dual redundant +24 Vdc power feed from the chassis backplane. An on-board power supply unit provides voltage conversion, supply conditioning and protection. The Trusted CI communicates with the Trusted TMR Processor via the triplicated InterModule Bus. When polled by the Trusted TMR Processor, the module’s bus interface votes the data 2 out of 3 (2oo3) from the Inter-Module Bus and transmits back its reply via all three Inter-Module Bus channels. The remainder of the Communications Interface is simplex. All communications transceivers are electrically isolated from each other and the module and have additional transient protection measures. The module internal supplies are isolated from the dual 24 Vdc feeds.

1.3.2. Communications

Ethernet Media Access Control (MAC) address configuration is held by the CI as part of its configuration information. Other information regarding port and protocol configuration is obtained from the TMR Processor, as part of the System.INI file. Data is transferred between the TMR Processor and the Communications Interfaces using a common interface called the Network Variable Manager. When data is read from a Trusted System, the data is obtained from the local copy maintained on the Communications Interface, providing a fast response. Data writes are more complicated. If a data write simply updated the local copy and was then relayed to the processor, the other Communications Interfaces in the system would carry different data. This may cause problems for redundant links. To overcome this problem, when data is written to a Communications Interface, it is first passed to the TMR Processor and the write is acknowledged immediately by the Communications Interface (to avoid communications delays). The processor updates its own database and then sends the data back to all Communications Interfaces so that they all have the same data. This can take one or two application scans. This means that subsequent reads will receive the old data immediately after the write, until the new data has been distributed. All changes to CI .INI parameters may be loaded online and will take immediate effect; the Communications Interface disconnects all communications and restarts. Communications is also restarted on an application online update and is shut down when the application is stopped.

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