Ideal annunciator display for any PLC

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Jan 2000 PLCs, DCSs & Controllers

Omniflex

Omniflex, the manufacturer of the Omni-16 annunciator range, has released the Omni-16c Serial Display, designed to work directly with PLCs in alarm monitoring applications. The Serial Display connects to the PLC via RS232 or as a multidrop using RS485 where up to 32 displays can be connected to a single port.

Using a serial modbus connection between the display and the PLC eliminates the need for an entire output card in the PLC to drive the annunciator, this alone resulting in savings. Further savings are achieved in the annunciator logic which now does not have to be written in the PLC as it is already programmed into the Omni-16c Serial Display. Thus, all the PLC has to do is send the input status to the display which then triggers the relevant alarm window. Each window can be programmed for a different alarm sequence which handles the annunciation functions, lamp flashing, audible relays, control pushbutton inputs, horns and group alarms etc. Furthermore, these sequences can be changed easily, something that would be infinitely more difficult in PLC logic.

There are many plant engineers who prefer to use PLCs for monitoring all plant inputs and as alarm displays still play a vital role in the modern control room, the separate cost of the annunicator plus the PLC and associated I/O cards is rather expensive. Furthermore, in an attempt to try and save costs, annunciation software is often written for the PLC which often takes longer than anticipated and does not offer the full functionality of a preprogrammed Omni-16c Serial Display. A major downside to programming the PLC to do the alarm logic is the burden this places on the PLC's CPU.

This new generation of serial display not only reduces total installation costs while offering a redundancy strategy for mission critical applications but it also removes the loading on the PLC's CPU and frees it up to do what it should be doing.

A single external pushbutton station can be used for all the Serial Displays, which are then synchronised or, if required, optional built-in control pushbuttons in each display can be used instead.

The display technology offers incandescent lamp or LED illumination options, the latter being either backlit or side-lit. As with all new Omni-16c annunciators, laser-printed legends replaces the older style manually engraved plastic windows as they are easier to produce and quick to duplicate.

As a further cost saving, an integral mains power supply (110/220) saves the need for a separate 24 V d.c. instrument supply

The new product range is also available in a true half-size 8-point version and an 8-point micro version which is the same size as a standard panel meter with full annunciator functionality, ideal for MCCs and RTU applications.

Omniflex

(031) 207 7466

ianl@omniflex.co.za

www.omniflexdirect.com

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Ideal annunciator display for any PLC

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