# Error reading S7-1500 DB through Kepware OPC

**URL:** <https://forum.inductiveautomation.com/t/error-reading-s7-1500-db-through-kepware-opc/10682>\
**Category:** General Discussion\
**Created:** [October 27, 2015, 4:40pm UTC](https://forum.inductiveautomation.com/t/error-reading-s7-1500-db-through-kepware-opc/10682 "2015-10-27T16:40:08Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![pgmo](https://avatars.discourse-cdn.com/v4/letter/p/d07c76/32.png) [@pgmo](https://forum.inductiveautomation.com/u/pgmo)\
**Post date:** [October 27, 2015, 4:40pm UTC](https://forum.inductiveautomation.com/t/error-reading-s7-1500-db-through-kepware-opc/10682/1 "2015-10-27T16:40:08Z")

</div>

From a S7-1500 I have to read the bits of the last two bytes of a DB (bytes 3848, 3849). Ignition cannot read those bits: tag quality is Unknown. Going to the kepware log I see the following reading error:

 ![](https://us1.discourse-cdn.com/inductiveautomation/original/2X/0/08f52fb6274da7747caac4913c1e3adeece93212.JPG)  

It seems that Ignition is telling Kepware to read 3 bytes from 3848: is there any reason for that?  
My bits are defined by using a UDT as follows (StartByte=3848):

 ![](https://us1.discourse-cdn.com/inductiveautomation/original/2X/1/134d915bd68eadd82639b3c73125808813985677.JPG)  

Any suggestion?

Thank you in advance

Regards

---

<div class="post-metadata">

**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 27, 2015, 4:50pm UTC](https://forum.inductiveautomation.com/t/error-reading-s7-1500-db-through-kepware-opc/10682/2 "2015-10-27T16:50:22Z")

</div>

Is it possible that any of the other tags in your UDT are addressing past 3908?

---

<div class="post-metadata">

**Author:** ![pgmo](https://avatars.discourse-cdn.com/v4/letter/p/d07c76/32.png) [@pgmo](https://forum.inductiveautomation.com/u/pgmo)\
**Post date:** [October 27, 2015, 5:01pm UTC](https://forum.inductiveautomation.com/t/error-reading-s7-1500-db-through-kepware-opc/10682/3 "2015-10-27T17:01:50Z")

</div>

Thank you Kevin. I’m quite sure that’s not the case: I double checked the tag database definition and all my variables are within DB addressable range - anyway I will check it again.

Regards