# Multiple tag groups for one modbus device **URL:** \ **Category:** Ignition\ **Created:** [January 2, 2021, 6:00pm UTC](https://forum.inductiveautomation.com/t/multiple-tag-groups-for-one-modbus-device/41902 "2021-01-02T18:00:31Z")\ **Posts on this page:** 1\ **Showing post:** 5
**Author:** ![Matrix\_Engineering](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/matrix_engineering/32/19781_2.png) [@Matrix\_Engineering](https://forum.inductiveautomation.com/u/Matrix_Engineering)\ **Post date:** [January 2, 2021, 7:23pm UTC](https://forum.inductiveautomation.com/t/multiple-tag-groups-for-one-modbus-device/41902/5 "2021-01-02T19:23:03Z")
An explanation on your span gaps query: > [@OPC-UA always requesting max allowable registers](http://forum.inductiveautomation.com/t/opc-ua-always-requesting-max-allowable-registers/8659/2): > > Unless there’s a bug, the behaviour you’ve described is not quite what happens. By default the driver attempts to minimize the number of requests. The primary way this is accomplished is by spanning gaps between registers, up to the max register setting (default 125). This means a request for {HR1, HR2, HR3} would request only HR1 through HR3 (3 registers), but a request for, say {HR1, HR2, HR10} would request HR1 though HR10 (10 registers) instead of using 2 requests to fetch HR1 + HR2 and HR… --- _[View the full topic](https://forum.inductiveautomation.com/t/multiple-tag-groups-for-one-modbus-device/41902)._