# UDT : opc item path with expression multiplcation and calc

**URL:** <https://forum.inductiveautomation.com/t/udt-opc-item-path-with-expression-multiplcation-and-calc/8333>\
**Category:** Ignition\
**Created:** [April 18, 2014, 7:53am UTC](https://forum.inductiveautomation.com/t/udt-opc-item-path-with-expression-multiplcation-and-calc/8333 "2014-04-18T07:53:36Z")\
**Posts on this page:** 3\
**Page:** 1

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**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:** [April 18, 2014, 7:53am UTC](https://forum.inductiveautomation.com/t/udt-opc-item-path-with-expression-multiplcation-and-calc/8333/1 "2014-04-18T07:53:36Z")

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In UDT, I would like to be able to have opc item path with expression with multiplication and more than 1 operator :

For example :  
{{byteStart+1}+{offset\*2}}

By combining “\*”, “+” and “-” we were able to create rules for calculate modbus ou S7 address

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**Author:** ![Piotr\_Zawalski](https://avatars.discourse-cdn.com/v4/letter/p/90ced4/32.png) [@Piotr\_Zawalski](https://forum.inductiveautomation.com/u/Piotr_Zawalski)\
**Post date:** [January 8, 2024, 10:20pm UTC](https://forum.inductiveautomation.com/t/udt-opc-item-path-with-expression-multiplcation-and-calc/8333/2 "2024-01-08T22:20:16Z")

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That's clear but..  
is there any way to use more complicated expressions like in alarms, where u have options to use string functions (split, right etc.) in expressions?  
I want to get substring from name or InstanceName, is this possible? Or why not?

Best regards  
Piter

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<div class="post-metadata">

**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:** [January 9, 2024, 6:57am UTC](https://forum.inductiveautomation.com/t/udt-opc-item-path-with-expression-multiplcation-and-calc/8333/3 "2024-01-09T06:57:04Z")

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Expression based on parameter are limited to the operator listed in:

[https://docs.inductiveautomation.com/display/DOC81/UDT+Parameters](https://docs.inductiveautomation.com/display/DOC81/UDT+Parameters)