Marshalling of accelerometer inputs: a neat solution from Monitran
19 March 2007
Monitran has released three MultiSelect units - th SC (self-contained), SB (switchbox) and RC (remote control) units - that can be used in a variety of configurations, giving manual access to up to 256 accelerometers and remote access to considerably more. They simplify site wiring when used to monitor industrial and plant processes, are ideal for implementing vibration-based predictive maintenance and can be accessed from a PC.
Bob Pickard, Monitran’s Technical Director, comments: “The MultiSelect units deliver the best of both worlds - remote selection of a specific unit and sensor via a PC, which could be located a long way away from the sensors, and the manual selection of a specific unit or sensor for inspection by oscilloscope or spectrum analyser”.
As for the MultiSelect units, the self-contained (SC) unit has a control panel and switching circuitry. It has inputs for up to 16 standard accelerometers, a control knob to select one of the 16 inputs, an industry standard 4-20mA output, an AC + bias output (available via the unit’s connector pins and a BNC on the control panel), an RS-485 interface connection and a digital display.
The MultiSelect SB (switchbox) is effectively the switching circuitry of the SC unit, and the MultiSelect RC (remote control) is effectively the control panel of the SC unit. The two can be separated and then connected via a proprietary 4-wire interface.
Pickard continues: “Separating the two allows the switchbox unit to be located close to the sensors, which may be in a hazardous area, and the control panel to be located elsewhere.”
Multiple MultiSelect SB units can be daisy-chained together via the 4-wire interface to build a network of MultiSelect units. In total, up to 15 switchbox (SB) units can be controlled by a self-contained (SC) unit, and up to 16 SB units can be controlled by a remote control (RC) unit. Either configuration would give access to the aforementioned 256 sensors.
Moreover, because the MultiSelect units incorporate the RS-485 interface, which is a ‘multidrop’ bus, several MultiSelect networks could be addressed by a PC. Also, once readings are available to a PC this opens up the possibility of remote control of the units and measurement of the sensors.
Pickard concludes: “The Monitran MultiSelect units, and their ability to be configured in many ways and linked to a PC, really does present a whole spectrum of opportunity – from close up scrutiny of a single sensor using an oscilloscope to the remote viewing of the sensor’s reading from the other side of the world.”
Monitran’s MultiSelect units are sampling now with full availability due in April 2007.
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