# Error Reading Modbus tcp
**URL:** https://discourse.nodered.org/t/error-reading-modbus-tcp/60786
**Category:** Industrial
**Tags:** modbus
**Created:** [4 April 2022 17:31 UTC](https://discourse.nodered.org/t/error-reading-modbus-tcp/60786 "2022-04-04T17:31:53Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@motosierra1141](https://discourse.nodered.org/u/motosierra1141)
#### Post date: [4 April 2022 17:31 UTC](https://discourse.nodered.org/t/error-reading-modbus-tcp/60786/1 "2022-04-04T17:31:53Z")
Hello everyone i'm trying to read Modbus wirh fc03 holding input register, everytime i get "Error: Modbus exception 3: Illegal data value (value cannot be written to this register)" i know that sounds like i'm trying to write in a read only address, but i'm using de read Modbus node, somebody help me please!!
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### Author:  [@MountainKing91](https://discourse.nodered.org/u/MountainKing91)
#### Post date: [5 April 2022 19:55 UTC](https://discourse.nodered.org/t/error-reading-modbus-tcp/60786/2 "2022-04-05T19:55:55Z")
Input registers (read only) are a different memory area than Holding registers (read/write). FC03 is "read holding registers.
Can you provide some detailed informations in order to reproduce your issue? Maybe paste your code?
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### Author:  [@motosierra1141](https://discourse.nodered.org/u/motosierra1141)
#### Post date: [5 April 2022 20:17 UTC](https://discourse.nodered.org/t/error-reading-modbus-tcp/60786/3 "2022-04-05T20:17:07Z")
Thanks For answering
this is the code looks like, the configuration of the node is this
and the error that apper is this one
i use Modscan 64 to connect to modbus tcp/ip software to connect to the same device and see if i can see the data, and it works, but in node red i cant
like you see in the image i can connect to holding register and see the data in addres 2700 and 2701, if i try to do this in to node red i cant, i dont know if holding register and FC 03 Read holding register are not the same thing. please help me!!
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### Author:  [@MountainKing91](https://discourse.nodered.org/u/MountainKing91)
#### Post date: [6 April 2022 20:21 UTC](https://discourse.nodered.org/t/error-reading-modbus-tcp/60786/4 "2022-04-06T20:21:24Z")
What node-red-contrib-modbus version and node-red versione do you have?
Have you tried reading different register addresses?
What device is your modbus server?
I am a bit confused about unit ID = 15, can you set it to 1 in your device (15 should be ok though)? Check also that you're register address isn't expressed as hex, that node expects it as decimal i think.
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### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [6 April 2022 20:28 UTC](https://discourse.nodered.org/t/error-reading-modbus-tcp/60786/5 "2022-04-06T20:28:46Z")
Out of interest, what do you get if you try reading
- Quantity 1 from 2700
- Quantity 1 from 2701
- Quantity 1 from 2702
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### Author:  [@motosierra1141](https://discourse.nodered.org/u/motosierra1141)
#### Post date: [7 April 2022 20:32 UTC](https://discourse.nodered.org/t/error-reading-modbus-tcp/60786/6 "2022-04-07T20:32:02Z")
in other register in other addresses i get the result, but in this adreess i cant read, it is a float 32 bits, i read the register in OPC and then imported to node red to use the data but it looks very weird that i cant read it with modbus node
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### Author:  [@motosierra1141](https://discourse.nodered.org/u/motosierra1141)
#### Post date: [7 April 2022 20:32 UTC](https://discourse.nodered.org/t/error-reading-modbus-tcp/60786/7 "2022-04-07T20:32:12Z")
i get the same error
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### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [6 June 2022 20:32 UTC](https://discourse.nodered.org/t/error-reading-modbus-tcp/60786/8 "2022-06-06T20:32:23Z")
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