# Issue addressing Siemens Instance DB in Ignition **URL:** \ **Category:** Ignition\ **Created:** [October 18, 2023, 8:45am UTC](https://forum.inductiveautomation.com/t/issue-addressing-siemens-instance-db-in-ignition/80635 "2023-10-18T08:45:56Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Sam\_Bermejo](https://avatars.discourse-cdn.com/v4/letter/s/e68b1a/32.png) [@Sam\_Bermejo](https://forum.inductiveautomation.com/u/Sam_Bermejo)\ **Post date:** [October 18, 2023, 8:45am UTC](https://forum.inductiveautomation.com/t/issue-addressing-siemens-instance-db-in-ignition/80635/1 "2023-10-18T08:45:57Z")
Hi all, I'm trying to access a tag in Ignition which comes from an Instance DB in a Siemens S7-1500 PLC, and for some reason it is not working. If I access a global db it works fine. For example: DB200 is my instance DB, and DB8 is my global DB. If I put the opc item path as: "ns=1;s=[S71500\_PLC]DB200,W0" it doesn't work (Quality bad), but if I change it to "ns=1;s=[S71500\_PLC]DB8,W0" it reads the value correctly. What is the issue here? Thanks. ---
**Author:** ![andrew.budaiev](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/andrew.budaiev/32/72921_2.png) [@andrew.budaiev](https://forum.inductiveautomation.com/u/andrew.budaiev)\ **Post date:** [October 18, 2023, 9:00am UTC](https://forum.inductiveautomation.com/t/issue-addressing-siemens-instance-db-in-ignition/80635/2 "2023-10-18T09:00:10Z")
Only global DB can be accessed if I remember correctly. ---
**Author:** ![andrew.budaiev](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/andrew.budaiev/32/72921_2.png) [@andrew.budaiev](https://forum.inductiveautomation.com/u/andrew.budaiev)\ **Post date:** [October 18, 2023, 9:05am UTC](https://forum.inductiveautomation.com/t/issue-addressing-siemens-instance-db-in-ignition/80635/3 "2023-10-18T09:05:48Z")
Maybe try this one > [@Siemens un-optimized addressing.....does this even work?](https://forum.inductiveautomation.com/t/siemens-un-optimized-addressing-does-this-even-work/61537/7): > > There is a little German company that has done an excellent job reverse engineering the S7 protocol, including all the bits nobody else has figured out, and has a pretty good OPC UA server for it: [OPC-Server for common PLCs](https://www.tanindustrie.de/en/Opc.php) ---
**Author:** ![zxcslo](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/zxcslo/32/61610_2.png) [@zxcslo](https://forum.inductiveautomation.com/u/zxcslo)\ **Post date:** [October 18, 2023, 9:40am UTC](https://forum.inductiveautomation.com/t/issue-addressing-siemens-instance-db-in-ignition/80635/4 "2023-10-18T09:40:11Z")
You can access instance DB also, at least I can on my PLC 1500: ![Screenshot_117](https://us1.discourse-cdn.com/inductiveautomation/original/3X/5/e/5e5d0e334a0e39dc2c99b65a823c14072f874761.png) ![Screenshot_118](https://us1.discourse-cdn.com/inductiveautomation/original/3X/b/0/b0143742a53752cc3d9424a93766f119a8f77c51.png) ![Screenshot_119](https://us1.discourse-cdn.com/inductiveautomation/original/3X/9/9/99af2954b5544c9aa59e87d8e593ecf5eae44b40.png) but you must disable " **Optimized block access**" ... ---
**Author:** ![Sam\_Bermejo](https://avatars.discourse-cdn.com/v4/letter/s/e68b1a/32.png) [@Sam\_Bermejo](https://forum.inductiveautomation.com/u/Sam_Bermejo)\ **Post date:** [October 18, 2023, 9:43am UTC](https://forum.inductiveautomation.com/t/issue-addressing-siemens-instance-db-in-ignition/80635/5 "2023-10-18T09:43:39Z")
I solved it 30 min ago. The issue in our case is that when the project got migrated, the "Optimized block access" got ticked. Once I unticked it, it now works. Thanks everyone for the help. ---
**Author:** ![Sam\_Bermejo](https://avatars.discourse-cdn.com/v4/letter/s/e68b1a/32.png) [@Sam\_Bermejo](https://forum.inductiveautomation.com/u/Sam_Bermejo)\ **Post date:** [October 18, 2023, 9:45am UTC](https://forum.inductiveautomation.com/t/issue-addressing-siemens-instance-db-in-ignition/80635/6 "2023-10-18T09:45:00Z")
Yes. During testing we had it configured like this. But I then migrated it, and not sure how the optimized bit got ticked. Thanks