# Scanclass/OPC group relation **URL:** \ **Category:** Ignition\ **Created:** [October 31, 2019, 2:21am UTC](https://forum.inductiveautomation.com/t/scanclass-opc-group-relation/29546 "2019-10-31T02:21:19Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![jianlinlee](https://avatars.discourse-cdn.com/v4/letter/j/7993a0/32.png) [@jianlinlee](https://forum.inductiveautomation.com/u/jianlinlee)\ **Post date:** [October 31, 2019, 2:21am UTC](https://forum.inductiveautomation.com/t/scanclass-opc-group-relation/29546/1 "2019-10-31T02:21:19Z")
Hi, I working with ignition 7.9. I’m using OPC DA interface with PLC to get the timestamp source. I notice that when I create new scanclass, Ignition will create additional OPC group for those tags using the scanclass. For example the default scanclass, creating OPC group “\_Group\_00”. new scanclass creating OPC group “\_Group\_01”. My question is, is there any limit how many tags can we use per scanclass? Also the OPC group name creation is it totally rely on scanclass ? or it generate automatically by it 's internal logic, for example : number of tags per OPC group. Thanks. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [October 31, 2019, 5:44pm UTC](https://forum.inductiveautomation.com/t/scanclass-opc-group-relation/29546/2 "2019-10-31T17:44:14Z")
> [@jianlinlee](#): > > My question is, is there any limit how many tags can we use per scanclass? Not on the Ignition side, but you may find the server you're connected to has some limit to the number of items belonging to a subscription/group. > [@jianlinlee](#): > > Also the OPC group name creation is it totally rely on scanclass ? or it generate automatically by it 's internal logic I think the subscription/group name is derived from the scan class name and rate.