# Siemens UDT / Array

**URL:** <https://forum.inductiveautomation.com/t/siemens-udt-array/11897>\
**Category:** Ignition\
**Created:** [July 6, 2016, 8:12am UTC](https://forum.inductiveautomation.com/t/siemens-udt-array/11897 "2016-07-06T08:12:17Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![StefanGronberg](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/stefangronberg/32/6288_2.png) [@StefanGronberg](https://forum.inductiveautomation.com/u/StefanGronberg)\
**Post date:** [July 6, 2016, 8:12am UTC](https://forum.inductiveautomation.com/t/siemens-udt-array/11897/1 "2016-07-06T08:12:17Z")

</div>

Hi, i have this atleast 1 DB that has an array 0…5, of an UDT, where a bunch of real’s (float) are declared.

I am trying to make a data type in ignition calling it “udtPumpSlag”, and then add opc tags trying to match the plcs udt.

But it seems i need to specify an exact address to the db/udt area.  
In the data type structure i named it, then added a new member, in the OPC Item Path,  
i do need to specify an exact adress, my thinking was i could use some offset, and when i add this data type structure to another data type structure (the array, in ignition) i only point to this data type struct and specify start address, and its offset would be the same, no matter if it started at 0.0 or 256.0 in the DB in the plc.

Or am my thinking wrong?

if the actual DB in the place looks like

`Static			
rigg	Array[0..5] of "udtPumpSpec"	0.0	
rigg[0]	udtPumpSpec	0.0	
rigg[1]	udtPumpSpec	68.0	
pumpSlag	Real	0.0	0.0
lyftHöjd	Real	4.0	0.0
kapacitet	Real	8.0	0.0
qUtlBel	Real	12.0	0.0
maxlUtlBel	Real	16.0	0.0
minHöj	Real	20.0	0.0
maxHöj	Real	24.0	0.0
qMinHöj	Real	28.0	0.0
qMaxHöj	Real	32.0	0.0
maxlMaxHöj	Real	36.0	0.0
mottryckIdle	Real	40.0	0.0
mottryckLåg	Real	44.0	0.0
mottryckHögOffset	Real	48.0	0.0
mottryckQuickOffset	Real	52.0	0.0
mottryckMaxlastOffset	Real	56.0	0.0
maxSjunkLåg	Real	60.0	0.0
maxSjunkHög	Real	64.0	0.0
rigg[2]	udtPumpSpec	136.0	
`  
etc.  
each rigg 0-5, would have 0-68 adressed, but each +1 gets another 68.  
So when i get to the tags pumpSlag, it has 68 + its own offset etc.

How would you do this?  
[attachment=0]udt.png[/attachment]