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As an outcome of this section of the course, you will:

  • Understand data acquisition concepts

  • Understand volt-free contact measurement

  • Understand sensor fundamentals

  • Know the common sensors used for point and track circuit monitoring

  • Know how to “identify” a site

  • Know how to select sensors and volt-free contacts for differing point machine arrangements

  • Know how to “size” and select the most appropriate data loggers

  • Be able to produce of installation drawings

 Understanding Data Acquisition Concepts

Digital acquisition

Digital event recording allows you to determine the present state of any relay (picked or dropped) and any change in state of any relay.

Front and Back Contacts

You may monitor spare front (normally open) and spare back (normally closed) relay contacts. Where back contacts are monitored the state of the relay will be the inverse of the state of the contacts.

To account for this discrepancy Mpec data loggers allow you to configure a digital input as a front or back contact; the TX-L then automatically ensures the true state of the relay (picked or dropped) is captured.

State Changes

All digital inputs are continuously monitored for any change in state, whenever a change is detected the nature of the change is captured locally (UP to DN, or DN to UP) along with a timestamp accurate to within 10 mS.

Initial States

When an Mpec data logger boots or restarts, it will capture the “initial state” of every digital input, this way you can see the present state of all monitored digital inputs at all times, even if no change in state has taken place on a particular channel.

Initial states are clearly indicated in the historical log, and are marked “UP” or “DN”.

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