# Modbus address mapping

**URL:** <https://forum.inductiveautomation.com/t/modbus-address-mapping/75768>\
**Category:** Ignition\
**Created:** [June 30, 2023, 12:36pm UTC](https://forum.inductiveautomation.com/t/modbus-address-mapping/75768 "2023-06-30T12:36:18Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![AlThePal](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/althepal/32/3603_2.png) [@AlThePal](https://forum.inductiveautomation.com/u/AlThePal)\
**Post date:** [June 30, 2023, 12:36pm UTC](https://forum.inductiveautomation.com/t/modbus-address-mapping/75768/1 "2023-06-30T12:36:18Z")

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When using Modbus address mapping, does the Ignition server poll all entries that are set up, or does it only poll entries that are requested by tags etc.?

We have a system where a few hundred registers are scattered around a range of several thousand PLC registers. It would easier to set up a single big block of registers so that we can request the data using the PLC registers, but not if it's actually going to be trying to read thousands of registers.

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**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:** [June 30, 2023, 12:38pm UTC](https://forum.inductiveautomation.com/t/modbus-address-mapping/75768/2 "2023-06-30T12:38:36Z")

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Only those you subscribe to.

Regardless, for various reasons, I'd recommend not using the addressing mapping at all. It's a poorly thought out design that introduces unnecessary indirection and confusion, for no benefit.

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [June 30, 2023, 12:42pm UTC](https://forum.inductiveautomation.com/t/modbus-address-mapping/75768/3 "2023-06-30T12:42:17Z")

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Pssst! My [alternate driver](https://inductiveautomation.com/moduleshowcase/module/automation-professionals-llc-advanced-modbus) offers OPC browsing directly on the standard address names....

/shameless plug