The rescue vessel John Ross has recently undergone a major upgrade to its onboard operating system, streamlining its new function as a long haul salvage vessel. Part of the worldwide fleet of rescue and salvage ships belonging to the international Smith Pentow Group, the John Ross can boast an impressive onboard monitoring and control system.
The task of designing and implementing a monitoring system throughout the ship, fell to Cape Town-based Spectrum Communications.
The software chosen was the Adroit scada 4.2 package, operating on two computers configured in Master/Standby mode. In the event that one computer fails, the standby machine can take over all the tasks performed by the Master computer.
The original PLC-based system had become unreliable due to faulty components that were no longer available and could not be replaced. The system comprised digital and analog signals, hard wired from the field into the PLC. The PLC controller, with pre-determined set points, converted the analog inputs to digital alarm outputs displayed on a mimic panel.
"Our brief," says Spectrum's Carl Webber, "was to design and implement a system that operated in the same way as the existing system, but with additional features." These included a new mimic panel and touch screen monitors. The panel, constructed of stainless steel, now indicates an alarm condition by means of a flashing LED. The operator can acknowledge the alarm either on the touch screen monitor or mimic panel. Once the alarm is acknowledged, the LED will stop flashing and remain on while the alarm condition is true.
The new scada system has full standby capabilities and remote scada monitoring via fibre optic links. Sensors fitted at the port and starboard engines, at each of the 16 exhausts per engine, on the 4 alternators, the steering mechanism, oil purifiers and on 16 engine bearings per side, are wired back to the Spectrum 'tele-FLEX' advanced telemetry I/O device. This interfaces the external analog and digital inputs with the Adroit scada software, which in turn is configured to produce alarm outputs back to the 'tele-FLEX' units, which also interface with the mimic panel. A total number of 157 analog inputs and 105 digital inputs are being monitored and 180 digital outputs are used to drive the mimic panel.
"With the aid of Adroit's 4.2 Advanced Scripting Options," concluded Webber, "we were able to process all inputs and outputs and perform the complex algorithms required to achieve our end product."
Dave Wibberley, Adroit Technologies
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