MadgeTech Event 101, Event 110 Application Note

Application Note

State, Event, and Pulse Data Recorders

Choosing Between a State, Event, or Pulse Recorder

The State, Event, and Pulse recorders, although related, each serve very different purposes in
meeting the needs of a specific application.

A State Recorder indicates how long an event lasts.

An Event Recorder indicates when an event occurs.

A Pulse Recorder indicates the number of times an event
occurred in a given time interval.

This application note will discuss the differences between these three types of units and provide
some insight into practical applications to help the user choose the correct product for their
application

State Recorder

The State Recorder records a time-stamped value whenever the state of the signal changes over a
period of time. This is useful when the user needs to be able to collect data on an event duration.

EXAMPLE:

If the user is monitoring traffic through a door, the State Recorder would take a data point:

MadgeTech, Inc.
[phone] Phone
[phone] Fax
www.madgetech.com
[e-mail]

879 Maple Street,
Contoocook, NH 03229

1. When the door opens

2. When the door closes

The State Recorder records the data points to indicate how long a door was open; that is, the
data collected tells the user that a change in the “state” of the door occurred:

1. When the door opened at 9:30:00 am

2. When the door closed at 9:30:05 am

The user can then calculate that the door was open for a period of 5 seconds.

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Application Note

However it should be noted that if the leading edge of a state occurs between position 0 and
position 1, it will be recorded as taking place at position 1.

The State Recorder samples the state of the input at fixed intervals. In order for a state change to
be recorded, the change must be present at the time it is sampled. If more than one transition
occurs between position 0 and position 1, only the state of the input at the time of the sample
will be recorded. Therefore, the sample period must be set to less than the minimum time
required for the input signal to rise and fall. If the change in state does not persist long enough to
be active at the time of sampling, it will be missed.

EXAMPLE:

If it takes 30 seconds for a garage door to open and close, the time period should be set to
less than 30 seconds to ensure the state change is not missed

MadgeTech, Inc.
[phone] Phone
[phone] Fax
www.madgetech.com
[e-mail]

879 Maple Street,
Contoocook, NH 03229

Another example of an application for the State Recorder is the monitoring of a furnace or pump
turning on and off, both of which have a long enough state change to be captured by the State
Recorder.

Event Recorder

The Event Recorder records a single direction time-stamped data point when an event takes place
within a fixed reading interval. This is useful when the user needs to be able to collect data on
when an event occurred, but does not need to know the duration of the event.

EXAMPLE:

If the user is monitoring the traffic flow through a door, the Event Recorder will take a data
point recording:

1. That the door opened, and

2. That the door opened again, and

3. That the door opened again.

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