# How do I create a block write?

**URL:** <https://forum.inductiveautomation.com/t/how-do-i-create-a-block-write/4044>\
**Category:** Ignition\
**Created:** [February 22, 2012, 9:48pm UTC](https://forum.inductiveautomation.com/t/how-do-i-create-a-block-write/4044 "2012-02-22T21:48:35Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![TimE](https://avatars.discourse-cdn.com/v4/letter/t/ee59a6/32.png) [@TimE](https://forum.inductiveautomation.com/u/TimE)\
**Post date:** [February 22, 2012, 9:48pm UTC](https://forum.inductiveautomation.com/t/how-do-i-create-a-block-write/4044/1 "2012-02-22T21:48:35Z")

</div>

I designed a laser displacement guage where I capture encoder data (distance) and laser data (height) with a PLC and then use a block group to transfer 10,000 encoder and 10,000 laser points to the database. After alot of filtering and calculations I now have a reduced dataset of about 1000 points (x,y) to pass back to the PLC to display on the local touchscreen.

The data to be written back to the plc is currently in a 2 column dataset with 1000 rows. I am wondering what would be the easiest way to do this.

Here is what I am thinking …  
Create 2000 tags in Kepware  
Put the following in a button script

`system.opc.writeValues(opcServer, itemPaths, values)
`

Question:  
Is the list, refered to in the help file, the same as a single column python dataset?  
[GuageBandTester.xml](https://us1.discourse-cdn.com/inductiveautomation/original/1X/32b2d6cb9ade958b387e1d04529bd86e9c472209.xml) (14 KB)

---

<div class="post-metadata">

**Author:** ![Travis.Cox](https://avatars.discourse-cdn.com/v4/letter/t/b9bd4f/32.png) [@Travis.Cox](https://forum.inductiveautomation.com/u/Travis.Cox)\
**Post date:** [February 22, 2012, 10:14pm UTC](https://forum.inductiveautomation.com/t/how-do-i-create-a-block-write/4044/2 "2012-02-22T22:14:09Z")

</div>

No, you would have to convert it to a basic list:`values = [row[0] for row in datasetVariable]`