# Tag driver not found response of read **URL:** \ **Category:** Module Development\ **Created:** [September 23, 2011, 2:40pm UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324 "2011-09-23T14:40:08Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![mazeyrat](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/mazeyrat/32/10955_2.png) [@mazeyrat](https://forum.inductiveautomation.com/u/mazeyrat)\ **Post date:** [September 23, 2011, 2:40pm UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324/1 "2011-09-23T14:40:08Z")
I try to read a db tag and i have the resul : tag driver not found what’s wrong ? see picture attached ![](https://us1.discourse-cdn.com/inductiveautomation/original/1X/15474a57ae7016975eaa8aed8b7c3253b86c96ac.jpg) ---
**Author:** ![Colby.Clegg](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/colby.clegg/32/3282_2.png) [@Colby.Clegg](https://forum.inductiveautomation.com/u/Colby.Clegg)\ **Post date:** [September 23, 2011, 4:14pm UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324/2 "2011-09-23T16:14:58Z")
The startup of modules happens in 2 phases: setup(), and startup(). In general, in setup() you can’t depend on other systems being available yet for use. The main systems contained in GatewayContext will be up, so you can do various initialization stuff (add listeners to system events, register extension points, add localization bundles, etc.), but you can’t do things like try to access a running tag provider. In startup(), the main systems should be up and running, and you should be able to do anything. So, long story short, try moving your code from setup() to startup(). Regards, ---
**Author:** ![mazeyrat](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/mazeyrat/32/10955_2.png) [@mazeyrat](https://forum.inductiveautomation.com/u/mazeyrat)\ **Post date:** [September 23, 2011, 7:31pm UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324/3 "2011-09-23T19:31:14Z")
I deplace the code in the startup section, but I have the same error : Tag driver not found ??? ![:scratch:](https://us1.discourse-cdn.com/inductiveautomation/original/1X/76d1620bec252bfac07050c889ff5a91dc8a9c25.gif ":scratch:") ---
**Author:** ![Colby.Clegg](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/colby.clegg/32/3282_2.png) [@Colby.Clegg](https://forum.inductiveautomation.com/u/Colby.Clegg)\ **Post date:** [September 23, 2011, 8:47pm UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324/4 "2011-09-23T20:47:18Z")
Oh, right, I missed another key thing in your code: your call to TagPathParser.parse is wrong. The signature of the overload you’re using is parse(defaultSource, path). Actually, the 3rd version you had, that’s commented out, should work (parse("[default]test2")). But try this: ```auto TagPathParser.parse("default","test2"); ``` Regards, ---
**Author:** ![mazeyrat](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/mazeyrat/32/10955_2.png) [@mazeyrat](https://forum.inductiveautomation.com/u/mazeyrat)\ **Post date:** [September 24, 2011, 7:54am UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324/5 "2011-09-24T07:54:34Z")
I have an exception or a null value, but i can’t achive a good read. I try with the 7.2.9-beta5 (b197). I have to change my version : 7.2.8 ? or 7.3beta. I read they was problem with acces right in 7.2.8 (read(Arrays.asList(path),null,true); for examp I use : Sql Tag real time default Internal Provider Built-in SQLTags provider I create a string tag test2 under the default Provider? Do I check other point ? could you send me a java code to test ? I really need to quickly valide read/write/subscription of a standart DB Tag from a java module in order to validate the use of Ignition for my project. I need a proof of concept on this point. Except this sdk difficulty, all other features seems to me very powerfull and flexible compared to other legacy scada solutions. Best regards. ---
**Author:** ![mazeyrat](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/mazeyrat/32/10955_2.png) [@mazeyrat](https://forum.inductiveautomation.com/u/mazeyrat)\ **Post date:** [September 24, 2011, 9:40am UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324/6 "2011-09-24T09:40:40Z")
my read tag issue is solved. I this i had sdk and igniton different version. 😕 I install then the 7.2.9 released of ignition and sdk. simple write tag example and subscription ? ---
**Author:** ![Carl.Gould](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/carl.gould/32/7262_2.png) [@Carl.Gould](https://forum.inductiveautomation.com/u/Carl.Gould)\ **Post date:** [September 29, 2011, 5:15pm UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324/7 "2011-09-29T17:15:56Z")
Here’s some examples: [code]// Writing TagPath path = TagPathParser.parse(“SomeFolder/MyTag”); context.getTagManager().write(path, 5.0); // Subscribing context.getTagManager().subscribe(path, new TagChangeListener() { ``` public void tagChanged(TagChangeEvent e) { TagValue value = e.getTag().getValue(); System.out.println("New value is: "+value.getValue()); } public TagProp getTagProperty() { return TagProp.Value; } ``` });[/code] ---
**Author:** ![mazeyrat](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/mazeyrat/32/10955_2.png) [@mazeyrat](https://forum.inductiveautomation.com/u/mazeyrat)\ **Post date:** [September 30, 2011, 9:30am UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324/8 "2011-09-30T09:30:08Z")
Thank a lot for this example, it works fine. Just another question: how to do synchronous write ? I means : write value 1 write value 2 write value 3 in order than the listener “receive” the value in the same order regards ---
**Author:** ![Carl.Gould](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/carl.gould/32/7262_2.png) [@Carl.Gould](https://forum.inductiveautomation.com/u/Carl.Gould)\ **Post date:** [September 30, 2011, 5:02pm UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324/9 "2011-09-30T17:02:26Z")
well, you don’t really. Write behavior differs depending on the tag type. The only way to truly do this would be to write 1, and then only write 2 after the listener receives the 1st change. ---
**Author:** ![mazeyrat](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/mazeyrat/32/10955_2.png) [@mazeyrat](https://forum.inductiveautomation.com/u/mazeyrat)\ **Post date:** [October 3, 2011, 7:35pm UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324/10 "2011-10-03T19:35:34Z")
Are the write function thread safe for an internal db tag ? My target is to write a mutithread module with writing operation of different internal db tag in different concurrent thread. ---
**Author:** ![Carl.Gould](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/carl.gould/32/7262_2.png) [@Carl.Gould](https://forum.inductiveautomation.com/u/Carl.Gould)\ **Post date:** [October 13, 2011, 4:09pm UTC](https://forum.inductiveautomation.com/t/tag-driver-not-found-response-of-read/3324/11 "2011-10-13T16:09:37Z")
yes, tag writing is thread-safe.