# emonPi frequency of logging

**URL:** <https://community.openenergymonitor.org/t/emonpi-frequency-of-logging/9640>\
**Category:** Emoncms\
**Tags:** emonpi\
**Created:** [3 January 2019 09:51 UTC](https://community.openenergymonitor.org/t/emonpi-frequency-of-logging/9640 "2019-01-03T09:51:24Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![moojuiceuk](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/moojuiceuk/32/7513_2.png) [@moojuiceuk](https://community.openenergymonitor.org/u/moojuiceuk)\
**Post date:** [3 January 2019 09:51 UTC](https://community.openenergymonitor.org/t/emonpi-frequency-of-logging/9640/1 "2019-01-03T09:51:24Z")

</div>

I have noticed the maximum frequency of logging voltage and current is 5 second intervals with Emoncms and emonpi. Is there a way of logging voltage and current to 1 second or sub 1 second intervals?

I need to spot brief undervoltage spikes that I suspect are below the 230v +10/ -6% tollerance allowed on a UK 1ph supply. It might seem strange, but I suspect an undervoltage issue is having an issue with a heat pump install, hence the need to log data to this resolution. Yes, I know it will take up SD card space, but needs must! Any ideas?

---

<div class="post-metadata">

**Author:** ![TrystanLea](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/trystanlea/32/31_2.png) [@TrystanLea](https://community.openenergymonitor.org/u/TrystanLea)\
**Post date:** [3 January 2019 15:31 UTC](https://community.openenergymonitor.org/t/emonpi-frequency-of-logging/9640/2 "2019-01-03T15:31:35Z")

</div>

Hello @moojuiceuk

It is possible to change to frequency of logging in the emonpi firmware here:  
[https://github.com/openenergymonitor/emonpi/blob/master/firmware/src/src.ino#L85](https://github.com/openenergymonitor/emonpi/blob/master/firmware/src/src.ino#L85)

you could then use the PHPTimeSeries feed engine which accepts interval lengths down to 1s. PHPFina would be better (use half the disk space) but would require further modifications to allow for a shorter interval.

---

<div class="post-metadata">

**Author:** ![moojuiceuk](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/moojuiceuk/32/7513_2.png) [@moojuiceuk](https://community.openenergymonitor.org/u/moojuiceuk)\
**Post date:** [5 January 2019 03:26 UTC](https://community.openenergymonitor.org/t/emonpi-frequency-of-logging/9640/3 "2019-01-05T03:26:42Z")

</div>

Thanks, I’ll see if the boss wants to order one for this site 🙂