---
title: Change of Value
slug: manufacturing-connect-edge-v2/change-of-value
docTags: 
createdAt: 2022-10-21T14:40:59.000Z
---

The **Change of Value** KPI displays the complete message payload when the current value differs from the previous value. If there is no substantial change, no output is displayed.

# Change of Value Overview

- Show the entire message payload when the current value is different than the previous value.
- A simple use-case of this KPI is: you want to see a message ONLY if there is a significant change from the previous value, otherwise if things are normal, no output is expected.
- By entering a **delta**, you can ignore some precision errors.
- If you enter delta as 0.0, even the smallest change will be detected by this KPI, or you can enter a delta of 0.1 (for example) if you want to allow ignore a change of +/- 0.1 from your previous value.
- **Map Field Name** asks you what is the field you want to observe for COV. This can be "value" or "asset\_online" etc. depending entirely on what is the input message you are sending to this KPI.
- The **timer interval** parameter is useful if the connected input tag is currently not polling, but you still want this KPI to publish a value every few seconds, defined by the aforementioned timer.
  - If you know your input is going to publish at the expected interval, it is better to disable this timer by entering 0 in this field.
- **Expected Output:** No output if the current value is the same as the previous value (+ or - *delta*), but outputs the entire input message if there is a change.

# Change of Value Parameter

| **Parameters**     | **Details**                                                                                                                                                      |
| ------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Map Field Name     | This parameter specifies the field to observe for Change of Value (COV), such as "value".                                                                        |
| Delta of Tolerance | This parameter allows you to specify the amount of difference between the current and previous values to ignore, thus helping to disregard some rounding errors. |
| Timer Interval     | Timer in milliseconds. If no event, use this timer to keep displaying the output continually. Enter zero to disable.                                             |

![](https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/xAubw0on-87rB6aRutB_T_image.png "Change of Value Parameter")

:::hint{type="info"}
**Note: **When creating an analytics flow with *Change of Value *KPI, refer the [Use the Change of Value KPI](docId\:LxIS1s6yDhwzjcDtyP3HM) guide for more details.
:::