==== Accumulator Difference driver ====

=== Description ===

This driver monitors an accumulating field value, for example an energy (kWh) or volume (L) register that continuously counts up. The driver captures the field value at a given interval (hourly, daily etc..) and computes the difference between the start and end of the interval. Current value and the four previous are provided.   

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==== Settings (center panel) ====

**Name** - The name is up to the user. Our suggestion is to choose a naming convention that makes the viewing the device list intuitive. Such as referring to the sensor and/or application. Keep the name short as it will be combined with the register name to create the default "Field" name (if added to "Fields")

**Active Check box** - Check this box and "Save changes" to run the driver. The driver program can be suspended by unchecking the box and clicking on "Save changes". 

**User Notes** - This space can be used to store information specific to the device and your application, such as: the asset being monitored, the purpose of monitoring, etc.

**eze System Notes** - In this space we provide a description of the driver's function. 

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**Accumulator Field** - Use the drop-down menu to select the Field to be monitored. 

**Interval** - Use the drop-down menu to select the differential's interval. Options are; Hourly, Daily, Weekly, Monthly or Yearly.   

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==== Status & Registers (right panel) ====


=== Device Status ===

**Driver info** - Typically this is the name from the program file

**Driver updated/version** - Date loaded or updated and the version of the driver

**Battery & Signal** - Signal indicates the progress through the script. If driver fails to operate, signal number indicates progress 

**Driver status** - Color and text of status bubbles give a quick visual reference of Communication, Operation, and Application

**Communication** - Com count indicates number of successful and unsuccessful data packets received

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=== Available registers ===

| Reg # | Reg Name | Description |
| 1 | **Accumulator value** | Current value in selected Field | 
| 2 | **Current interval partial diff** | Differential between value at beginning of interval and current value | 
| 3 | **Previous interval diff** | Most recent interval differential captured. **Daily example:** Yesterday's differential |
| 4 | **2nd interval diff** | Second most recent interval differential captured |
| 5 | **3rd interval diff** | Third most recent interval differential captured |
| 6 | **4th interval diff** | Fourth most recent interval differential captured |
| 7 | **Value at start of current interval** | Speed of travel is given as meters per second |
| 8 | **Interval identifier** | Current interval step, out of a complete cycle (expressed as a number). See table below |

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| **Interval option** | **Description** | **Cycle** | **Example of number reference** |
| Hourly| Begins at top of hour | 0 to 23 | 0 = Midnight to 1 am |
| Daily | Begins at Midnight | 1 to 31 | 1 = 1st day of Month | 
| Weekly (Mon-Sun) | Begins Monday | 1 to 52 | 1 = Monday |
| Weekly (Sun-Sat) | Begins Sunday | 1 to 52 | 1 = Sunday |
| Monthly | Begins first of the Month | 1 to 12 | 1 = January |
| Yearly | Begins January 1st | N/A |