# Curiosity? Gateway Timer Event Scripts

**URL:** <https://forum.inductiveautomation.com/t/curiosity-gateway-timer-event-scripts/102368>\
**Category:** General Discussion\
**Created:** [February 14, 2025, 2:23pm UTC](https://forum.inductiveautomation.com/t/curiosity-gateway-timer-event-scripts/102368 "2025-02-14T14:23:22Z")\
**Posts on this page:** 1\
**Showing post:** 9

<div class="post-metadata">

**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [February 21, 2025, 5:18pm UTC](https://forum.inductiveautomation.com/t/curiosity-gateway-timer-event-scripts/102368/9 "2025-02-21T17:18:04Z")

</div>

As Ryan suggests, don't count in a timer event. The timing is not very precise.

To get retention of prior time, you need at least two timestamps to hold state, updated when the signal changes. A stop timestamp, and an adjusted start timestamp. The start timestamp needs to be adjusted backwards from `now()` by the amount accumulated before.

Drop these tags into a test folder to see how to set this up:

```python
{
  "tags": [
    {
      "valueSource": "expr",
      "expression": "if(\n\t{[.]RTO_Reset},\n\t0.0,\n\t0.001 * dateDiff(\n\t\t{[.]RTO_StartTS},\n\t\tif(\n\t\t\t{[.]RTO_Signal},\n\t\t\tnow(250),\n\t\t\t{[.]RTO_StopTS}\n\t\t),\n\t\t\u0027ms\u0027\n\t)\n)",
      "dataType": "Float8",
      "name": "RTO_Accum",
      "formatString": "#,##0.000",
      "tagType": "AtomicTag"
    },
    {
      "valueSource": "memory",
      "eventScripts": [
        {
          "eventid": "valueChanged",
          "script": "\tnowTS \u003d system.date.now()\n\tif currentValue.value:\n\t\t# Signal is true. Write the current timestamp to both state tags.\n\t\tsystem.tag.writeBlocking([\u0027[.]RTO_StartTS\u0027, \u0027[.]RTO_StopTS\u0027], [nowTS, nowTS])\n"
        }
      ],
      "dataType": "Boolean",
      "name": "RTO_Reset",
      "value": false,
      "tagType": "AtomicTag"
    },
    {
      "valueSource": "memory",
      "eventScripts": [
        {
          "eventid": "valueChanged",
          "script": "\tresetting, startTS, stopTS \u003d [qv.value for qv in system.tag.readBlocking([\u0027[.]RTO_Reset\u0027, \u0027[.]RTO_StartTS\u0027, \u0027[.]RTO_StopTS\u0027])]\n\tif not resetting:\n\t\tnowTS \u003d system.date.now()\n\t\tif currentValue.value:\n\t\t\t# Signal is true. If stopTS is after startTS, the new startTS must\n\t\t\t# be moved back before nowTS by their delta.\n\t\t\tif stopTS.after(startTS):\n\t\t\t\tpriorMS \u003d stopTS.time - startTS.time\n\t\t\t\tsystem.tag.writeBlocking([\u0027[.]RTO_StartTS\u0027], [system.date.addMillis(nowTS, -priorMS)])\n\t\t\telse:\n\t\t\t\tsystem.tag.writeBlocking([\u0027[.]RTO_StartTS\u0027], [nowTS])\n\t\telse:\n\t\t\t# Signal is false. Just write the current timestamp to stopTS\n\t\t\tsystem.tag.writeBlocking([\u0027[.]RTO_StopTS\u0027], [nowTS])\n"
        }
      ],
      "dataType": "Boolean",
      "name": "RTO_Signal",
      "value": false,
      "tagType": "AtomicTag"
    },
    {
      "valueSource": "memory",
      "dataType": "DateTime",
      "name": "RTO_StartTS",
      "formatString": "yyyy-MM-dd h:mm:ss aa",
      "value": 1740157975856,
      "tagType": "AtomicTag"
    },
    {
      "valueSource": "memory",
      "dataType": "DateTime",
      "name": "RTO_StopTS",
      "formatString": "yyyy-MM-dd h:mm:ss aa",
      "value": 1740157975856,
      "tagType": "AtomicTag"
    }
  ]
}

```

In the accumulator expression tag, adjust the `now(250)` to the update pace you want.

Edit: If you do many of these, move the two scripts to functions in the Gateway Scripting Project's library, so the tag events can be one-liners.

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