Sensors

About Sensors

Sensors are used to collect data from the OPC Server.  All data collected from the field comes via the OPC Server.

A Sensor may or may not correspond with a physical sensor in the field.  For example Manual Down Time and Custom sensors do not have physical counterparts in the factory. All physical sensors in the factory detect product passing thus production counts are recorded. Run/Stop status and Rate information is interpolated by the data collection software from the presence and frequency (rate) of counts detected. Automatic Stop reasons can also be geneated and logged in esCollate if the machinery supports error codes.

For each Sensor there is a corresponding binary file that the data collected by a Sensor is stored in.  The data collected by a Sensor is not stored in the database.

There are seven types of Sensors:

• Count
  Count Sensors are used to collect a count of items, such as the number of boxes that pass a point on a manufacturing line.
• Count Status
  Count Status Sensors are used to collect a count of items, such as the number of boxes that pass a point on a manufacturing line. They also track the Run/Stop status of the Line Area at the point where Counts are collected. These should be used in place of Count Sensors if the Count is collected from a different part of the Line/Line Area to where the Down Time is detected. That is when there are two (or more) physical sensors in a single Line Area.
• Rate
  Rate Sensors are used to collect Down Time and Down Time Reasons for a Line Area. They also log the Rate at which product is produced. These metrics are used for OEE statisics.
• Reject
  Reject Sensors are used to collect a count of rejected items, such as the number of items rejected by a check weigher.
• Analogue
  Analogue Sensors are used to collect data such as temperatures or motor currents.
• Custom
  Custom Sensors are are used to collect User specific repeating data such as product weights or waste reasons and weights.
• Manual Down Time
  Manual Down Time Sensors are used in place of a Rate Sensor to configure Line Area where all data will be manually entered.

Each Sensor Type has different attributes.  When adding a new Sensor, first enter the Name then the Sensor Type, this will reveal the further attributes that are relevant for the selected Sensor Type.

Once a Sensor has been saved the Sensor Type cannot be changed.

Delta

The Delta value is common to all Sensors.  The Delta value determines the granularity of records stored in the Binary Files for a Sensor.  A larger Delta value will result in fewer records in the Binary File for a Sensor.  However values retrieved from the Binary File will be interpolated over a longer duration.  A smaller Delta value will result in more records in the Sensor's Binary File and shorter interpolation times, but file sizes could be larger and data retrieval times longer.

The appropriate Delta value for the Sensor depends on both the variability of the data being measured and the degree of accuracy required.

During commissioning of an esCollate implementation the data being stored in the Binary Files should be monitored and appropriate adjustment of the Delta values made.

The Delta value is the change in the data value per minute that triggers the current record to be finalised and a new record to be created.  For example, if the current rate is 100 items per minute and the delta is set to 5 items per minute, then when the rate becomes greater than 105 items per minute or less than 95 items per minute, the current count record will be finalised and a new record created.