# Reference tag resource cost vs. another tag **URL:** \ **Category:** Ignition\ **Created:** [May 2, 2024, 8:14pm UTC](https://forum.inductiveautomation.com/t/reference-tag-resource-cost-vs-another-tag/89857 "2024-05-02T20:14:05Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![wpmccormick](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/wpmccormick/32/13940_2.png) [@wpmccormick](https://forum.inductiveautomation.com/u/wpmccormick)\ **Post date:** [May 2, 2024, 8:14pm UTC](https://forum.inductiveautomation.com/t/reference-tag-resource-cost-vs-another-tag/89857/1 "2024-05-02T20:14:05Z")
What is the cost savings (if any) in terms of system resources of a Reference tag vs. another instance of an opc tag? CPU? Memory? Network? PLC? For just a handful of duplicate tags I would imagine the cost difference is negligible. But if there is any cost savings, how does it scale when considering 100's or 1000's of tags? And is there some known point of marked difference. Cheers! ---
**Author:** ![Jose\_Hervas\_Chico](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jose_hervas_chico/32/69260_2.png) [@Jose\_Hervas\_Chico](https://forum.inductiveautomation.com/u/Jose_Hervas_Chico)\ **Post date:** [November 4, 2024, 1:50pm UTC](https://forum.inductiveautomation.com/t/reference-tag-resource-cost-vs-another-tag/89857/2 "2024-11-04T13:50:41Z")
We are also interested on that topic, have you found an answer? Thanks a lot! ---
**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:** [November 4, 2024, 2:14pm UTC](https://forum.inductiveautomation.com/t/reference-tag-resource-cost-vs-another-tag/89857/3 "2024-11-04T14:14:56Z")
For OPC tags, I would just make another. Ignition will optimize away the extra traffic as long as the subscription pace is the same. Then nothing breaks if the original tag is deleted. I would consider this worth it even if the extra OPC tags took more resources than a reference tag. (But I doubt the resource difference is significant.) ---
**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:** [November 4, 2024, 3:47pm UTC](https://forum.inductiveautomation.com/t/reference-tag-resource-cost-vs-another-tag/89857/4 "2024-11-04T15:47:08Z")
What's the use case where you would be considering adding a reference tag vs duplicate OPC tag? ---
**Author:** ![ryan.white](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/ryan.white/32/73193_2.png) [@ryan.white](https://forum.inductiveautomation.com/u/ryan.white)\ **Post date:** [November 4, 2024, 10:44pm UTC](https://forum.inductiveautomation.com/t/reference-tag-resource-cost-vs-another-tag/89857/5 "2024-11-04T22:44:46Z")
I have a case where we have several process values that each have a UDT with limit and alarm controls, but the process value also controls a PID or similar. We often just display the process values grouped by their location on the machine/product. We also have templates/popups for viewing/controlling the PIDs and want to display the process value associated with the shown PID. Each PID has its own folder that contains tags linked to the different control values in the PLC as well as the CV and PV. Currently I just make a the PV tag in the PID folder a reference tag that points to the process value in its UDT. This allows me to have a single UDT instance per process value while still associating the process value with the control items that utilize it. ---
**Author:** ![Jose\_Hervas\_Chico](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jose_hervas_chico/32/69260_2.png) [@Jose\_Hervas\_Chico](https://forum.inductiveautomation.com/u/Jose_Hervas_Chico)\ **Post date:** [November 5, 2024, 11:50am UTC](https://forum.inductiveautomation.com/t/reference-tag-resource-cost-vs-another-tag/89857/6 "2024-11-05T11:50:57Z")
> [@pturmel](#): > > he resource difference is significant.) We have OPC tags that retrieves the value, but we forward this signal to other layers, so we have a folder with all signals that are forwarded (for clarity), and we have the doubt if it is worth to duplicate the signal or have a reference to the original OPC. ---
**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:** [November 5, 2024, 2:00pm UTC](https://forum.inductiveautomation.com/t/reference-tag-resource-cost-vs-another-tag/89857/7 "2024-11-05T14:00:40Z")
Reference tag seems appropriate here. A duplicate OPC tag has more overhead and cost, as it means a duplicate monitored item on the server and a duplicate item being polled depending on the server and driver implementation. ---
**Author:** ![Jose\_Hervas\_Chico](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jose_hervas_chico/32/69260_2.png) [@Jose\_Hervas\_Chico](https://forum.inductiveautomation.com/u/Jose_Hervas_Chico)\ **Post date:** [November 5, 2024, 2:43pm UTC](https://forum.inductiveautomation.com/t/reference-tag-resource-cost-vs-another-tag/89857/8 "2024-11-05T14:43:36Z")
Thanks a lot Kevin 💪