# SimpleTagProvider and scanclasses **URL:** \ **Category:** Ignition\ **Created:** [June 26, 2018, 7:14am UTC](https://forum.inductiveautomation.com/t/simpletagprovider-and-scanclasses/18618 "2018-06-26T07:14:17Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Amarth](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/amarth/32/3313_2.png) [@Amarth](https://forum.inductiveautomation.com/u/Amarth)\ **Post date:** [June 26, 2018, 7:14am UTC](https://forum.inductiveautomation.com/t/simpletagprovider-and-scanclasses/18618/1 "2018-06-26T07:14:17Z")
Hi all, I’m wondering if it is possible to create new scanclasses on a SimpleTagProvider. The need comes from the fact I use the MQTT modules. The MQTT Engine (Cloud) is a SimpleTagProvider and I need to create different scanclasses than the ones existing on the transmitter (Field) side. Different rates, driven scanclasses, history scan classes, … The thing is that, for this provider, the scanclass button, in the Tag Browser is greyed. ![](https://us1.discourse-cdn.com/inductiveautomation/original/2X/a/a873e3b60b88588124231bd263e9a75e5782df49.png) ---
**Author:** ![Kyle\_Chase](https://avatars.discourse-cdn.com/v4/letter/k/9de0a6/32.png) [@Kyle\_Chase](https://forum.inductiveautomation.com/u/Kyle_Chase)\ **Post date:** [June 26, 2018, 2:26pm UTC](https://forum.inductiveautomation.com/t/simpletagprovider-and-scanclasses/18618/2 "2018-06-26T14:26:00Z")
MQTT engine does not use scan classes, because the tags are all driven on an event. To change the rate at which your edge gateways are polling, you will have to log into them and change the scan class locally. ---
**Author:** ![Amarth](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/amarth/32/3313_2.png) [@Amarth](https://forum.inductiveautomation.com/u/Amarth)\ **Post date:** [June 26, 2018, 2:28pm UTC](https://forum.inductiveautomation.com/t/simpletagprovider-and-scanclasses/18618/3 "2018-06-26T14:28:24Z")
Thank you for the reply. Just to be sure, does it mean that we cannot have different polling rates on the field and on the cloud ? ---
**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:** [June 26, 2018, 2:33pm UTC](https://forum.inductiveautomation.com/t/simpletagprovider-and-scanclasses/18618/4 "2018-06-26T14:33:27Z")
The cloud isn’t polling. ---
**Author:** ![Kyle\_Chase](https://avatars.discourse-cdn.com/v4/letter/k/9de0a6/32.png) [@Kyle\_Chase](https://forum.inductiveautomation.com/u/Kyle_Chase)\ **Post date:** [June 26, 2018, 2:38pm UTC](https://forum.inductiveautomation.com/t/simpletagprovider-and-scanclasses/18618/5 "2018-06-26T14:38:07Z")
MQTT engine does not have or need scan classes, because the values are updated as they hit the broker from the field. There is no “cloud” (MQTT Engine) polling rate. There might be some timing settings in regards to holding delays on the push from Transmission to the broker, but I do not have the module installed right now. What are you using for your edge device? ---
**Author:** ![Amarth](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/amarth/32/3313_2.png) [@Amarth](https://forum.inductiveautomation.com/u/Amarth)\ **Post date:** [June 26, 2018, 2:51pm UTC](https://forum.inductiveautomation.com/t/simpletagprovider-and-scanclasses/18618/6 "2018-06-26T14:51:47Z")
Let me answer my question in a different way then. I wish to change the history rate on my cloud site. On the field, let us say that I send data to history once a minute for exemple. On the cloud, I’m interested in storing my value only once an hour. From what I understand, it is not possible “out-of -the-box” and I will have to create a field hourly scanclass. The field tags with this scanclass should be sent to the Edge Nodes. Am I right ? ---
**Author:** ![mmunin](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@mmunin](https://forum.inductiveautomation.com/u/mmunin)\ **Post date:** [May 21, 2021, 6:09pm UTC](https://forum.inductiveautomation.com/t/simpletagprovider-and-scanclasses/18618/7 "2021-05-21T18:09:31Z")
Did you ever solve this problem? ---
**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:** [May 21, 2021, 6:15pm UTC](https://forum.inductiveautomation.com/t/simpletagprovider-and-scanclasses/18618/8 "2021-05-21T18:15:04Z")
IIRC, the canonical way to do this is to create a reference tag in another provider, and historize that tag with your desired parameters.