# Unable to read multiple Modbus Register using Modbus Serial Port

**URL:** <https://discourse.nodered.org/t/unable-to-read-multiple-modbus-register-using-modbus-serial-port/73613>\
**Category:** General\
**Tags:** modbus\
**Created:** [12 January 2023 22:35 UTC](https://discourse.nodered.org/t/unable-to-read-multiple-modbus-register-using-modbus-serial-port/73613 "2023-01-12T22:35:06Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![1onkar](https://avatars.discourse-cdn.com/v4/letter/1/ba9def/32.png) [@1onkar](https://discourse.nodered.org/u/1onkar)\
**Post date:** [12 January 2023 22:35 UTC](https://discourse.nodered.org/t/unable-to-read-multiple-modbus-register-using-modbus-serial-port/73613/1 "2023-01-12T22:35:07Z")

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I am trying to read Modbus data over Serial RS485 Port. The device has 242 registers in float format. I am able to read only first 99 registers using Modbus Read. Please help me how to read all registers in one go. I can read all registers in other apps like kepware opc server.  
Thanks

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**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [12 January 2023 23:07 UTC](https://discourse.nodered.org/t/unable-to-read-multiple-modbus-register-using-modbus-serial-port/73613/2 "2023-01-12T23:07:15Z")

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> [@1onkar](#):
>
> The device has 242 registers in float format. I am able to read only first 99 registers using Modbus Read. Please help me how to read all registers in one go

You can't read that many in one go due to modbus protocol limitations.

You will need to read them in 3 goes. And you should do that sequentially (one after the other)

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**Author:** ![1onkar](https://avatars.discourse-cdn.com/v4/letter/1/ba9def/32.png) [@1onkar](https://discourse.nodered.org/u/1onkar)\
**Post date:** [13 January 2023 13:18 UTC](https://discourse.nodered.org/t/unable-to-read-multiple-modbus-register-using-modbus-serial-port/73613/4 "2023-01-13T13:18:05Z")

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Hi Steve,

Thanks for your suggestion, it works using Sequence.  
Thanks and have a nice day !

Kind Regards  
Onkar

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [31 January 2023 16:34 UTC](https://discourse.nodered.org/t/unable-to-read-multiple-modbus-register-using-modbus-serial-port/73613/5 "2023-01-31T16:34:14Z")

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