OMNIfacts eNewsletter
  News from Omniflex
EndUser Electronic Edition
2004-05-19 00:00:00


Omnifacts is published by Omniflex Pty Ltd. This newsletter is designed to inform and educate in the areas of monitoring and control.
This publication may be freely redistributed if copied in its entirety.  Portions of this newsletter may be
reprinted with permission

Optical Pyrometer Signals Linearised by Omniterm TxB
Ian Loudon

    High temperature measurement requires the use of non-contact techniques for example, Optical or Radiametric Pyrometers,  many of these devices in service produce mV or mA signals proportional to the physical measurement. However many of these devices are not linear to temperature and to be integrated into process control and monitoring systems where they need to be linearised to the temperature scale.

    It's so easy now with Omniterm TxB Model C2401 - the programmable universal transmitter. We supply you with a special configuration file called a DVU file into which the linearised break points can be inserted. The result is the ability to input your non-linear say mV signal and get linear 4-20mA representing degrees Celsius. Your panel meter now reads in degrees C and has a linear response for the measurement range concerned.

    This is just one of the many applications TxB can be applied to and it's still the same off the shelf item you would use for your usual signal conditioning.

    Some interesting Linearizer Applications for TxB

  • Cylindrical Tank Linearisation
  • V Notch Weir
  • Temperature devices
  • Flow Applications
  • Burner Controls Signal Conditioning

Ground Loops in signal conditioning - Why Isolate?

Ground Loops are a common problem in every plant, most often misunderstood and often difficult to diagnose from the installation.

The first thing to remember is that the ground potential varies from location to location it is rarely the same.

Sensors and transducers fitted into the process can be connected to ground at the measurement point or can be left floating. A signal conditioner would usually be connected to a good ground point, if a measurement circuit is connected to ground at two or more points a ground loop will be created. Thus creating the possibility that high current may flow between the two ground points via the cabling which in turn affects the measurement signals. It is not uncommon to find 100V difference between two points in an industrial plant.

It's this fact that causes many headaches on the Plant. Signal Isolation of the Input and its associated Output will eliminate this form of interference.

All Omniflex signal conditioners provide isolation Input to Output and to power supply, another potential source of ground loop problems.

The LPI Loop Powered Isolator Model C2063 and LPS Loop splitter C2464 provide solutions where ground loops present problems due to instrumentation not being isolated. The Loop Power isolator is simply inserted into the existing 4-20mA loop, derives its power from the loop and provides 1500V isolation between the input and output.

New! Conet OPC Server with Date and Time Stamp Handling

Just released a Conet OPC server upgrade that handles date and time stamped events from source. Omniflex products like SER260 Sequential Events Recorder and Maxiflex have the ability to Date and Time stamp changes of state as they happen at the input. This ensures that when you want to review the sequence of events leading up to an alarm or trip you can see what chronological order things occurred in. Time tagging or stamped change of state at the SCADA often is inaccurate as the Network communications can have delays which makes events appear in a different order. Also SCADA Polling cycle times affect this as several events may appear to occur at the same time because the SCADA only gets round to poll that controller once every few seconds at best. Time stamp at source gives you better than 1 millisecond or 10s of millisecond resolution on all your plant events.

The latest OPC Server now handles these events and presents them to the SCADA client for archiving into its database for later analysis. Don't miss events or be left with inadequate data for your first up alarm or sequence of events analysis.

Last Month:

Last month we talked about several important topics including:

  • Optical Pyrometer Signals Linearised by Omniterm TxB
  • Ground Loops in signal conditioning - Why Isolate?
  • New! Conet OPC Server with Date and Time Stamp Handling

If you missed these or other key discussions,
you can find the back issues on the newsletters page of our website:


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This publication may be freely redistributed if copied in its ENTIRETY.  Portions of this newsletter may be reprinted with permission.

(c) Copyright 2003 OMNIFLEX PTY LTD 

In this Issue
Optical Pyrometer Signals Linearised by Omniterm TxB
Ground Loops in signal conditioning - Why Isolate?
New! Conet OPC Server with Date and Time Stamp Handling
Last Month's Issue

Universal Programmable Transmitter TxB

Lineariser option - Key in your breakpoints yourself

Get the free configuration file from us

Want help with Linearisation?

Talk to us we can assist you with the set-up of your TxB in Linearization applications.

LPI Loop Powered Isolator

  • Very Low Volt drop <3V @20mA
  • Compact Size
  • DIN rail Mounting
  • Up to 1k Load capability
  • Plug and Play- no cal/trim required

LPS Loop Splitter

  • Make one loop into two
  • Fully isolated and independant
  • 24Vdc powered
  • Up to 1k Load capability




Conet OPC Server

  • For Windows Operating Systems
  • No More dedicated driver solutions.
  • PCI card compatible
  • Simple configuration Interface

Conet OPC Server with Date and Time Stamp handling

  • Don't miss the first up alarm
  • Review the sequence of events from the field with true time of occurence
  • Handles Maxiflex and SER260 Event Streams
  •  Any OPC client can retrieve the data