# Module error follows position, not hardware

**URL:** <https://community.br-automation.com/t/module-error-follows-position-not-hardware/4410>\
**Category:** Controls & Vision\
**Tags:** plc\
**Created:** [September 25, 2024, 7:03pm UTC](https://community.br-automation.com/t/module-error-follows-position-not-hardware/4410 "2024-09-25T19:03:56Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![jameswroscoe](https://avatars.discourse-cdn.com/v4/letter/j/FF8800/32.png) [@jameswroscoe](https://community.br-automation.com/u/jameswroscoe)\
**Post date:** [September 25, 2024, 7:03pm UTC](https://community.br-automation.com/t/module-error-follows-position-not-hardware/4410/1 "2024-09-25T19:03:56Z")

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I have a X20 CPU with 2 MM2436 PWM drive modules. The first on the rail shows OK status and reports data. The second does not, and the ‘r’ light is slowly flashing green. I have tried swapping modules, replacing bases and terminals, and unwiring everything but DC power - nothing changes; the second module in line always shows FALSE status. What should I try?

FYI - this is for a configuration and program which has already deployed several functioning systems.

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**Author:** ![alexander.hefner](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/alexander.hefner/32/111_2.png) [@alexander.hefner](https://community.br-automation.com/u/alexander.hefner)\
**Post date:** [September 25, 2024, 7:22pm UTC](https://community.br-automation.com/t/module-error-follows-position-not-hardware/4410/2 "2024-09-25T19:22:41Z")

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Hi,

As I understood you cross-exchanged the X20MM2436, and also cross-exchanged the backplane modules but always the 2nd module is affected, right?  
Are those 2 modules the only ones at the X2X interface, and both backplane modules are X20BM11?

I’m asking because it sounds a bit like an addressing topic: using X20BM11 and two modules, the X2X addresses of the modules should be (automatically assigned) 1 and 2 at the interface IF6 - does that match to the addresses shown in the hardware tree in the physical view of the Automation Studio project?

Best regards!

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**Author:** ![corne.geerts](https://avatars.discourse-cdn.com/v4/letter/c/FF8800/32.png) [@corne.geerts](https://community.br-automation.com/u/corne.geerts)\
**Post date:** [September 26, 2024, 8:38am UTC](https://community.br-automation.com/t/module-error-follows-position-not-hardware/4410/3 "2024-09-26T08:38:57Z")

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The X20MM2436 is a double width module. Is a [X20BM31](https://www.br-automation.com/en/products/io-systems/x20-system/bus-modules/x20bm31/) used as backplane?

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**Author:** ![jameswroscoe](https://avatars.discourse-cdn.com/v4/letter/j/FF8800/32.png) [@jameswroscoe](https://community.br-automation.com/u/jameswroscoe)\
**Post date:** [September 26, 2024, 1:04pm UTC](https://community.br-automation.com/t/module-error-follows-position-not-hardware/4410/4 "2024-09-26T13:04:33Z")

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That was it - a local B&R vendor helped us diagnose. The builder of the chassis that houses our PLC was new and didn’t follow the drawing. Works a charm with the proper backplanes!

Thanks!