# Join Device Modbus Device

**URL:** <https://discourse.nodered.org/t/join-device-modbus-device/11372>\
**Category:** General\
**Created:** [21 May 2019 15:05 UTC](https://discourse.nodered.org/t/join-device-modbus-device/11372 "2019-05-21T15:05:38Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![afiqkimii](https://avatars.discourse-cdn.com/v4/letter/a/e9bcb4/32.png) [@afiqkimii](https://discourse.nodered.org/u/afiqkimii)\
**Post date:** [21 May 2019 15:05 UTC](https://discourse.nodered.org/t/join-device-modbus-device/11372/1 "2019-05-21T15:05:38Z")

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When registering a device, we need to fill 1.register name 2.register address 3.R/W method  
The R/W method has read function 01,02,03,04 write function 05,06,15,16.  
Can i know the details of the list of those R/W method?  
thank you so much

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<div class="post-metadata">

**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:** [21 May 2019 21:45 UTC](https://discourse.nodered.org/t/join-device-modbus-device/11372/2 "2019-05-21T21:45:38Z")

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Modbus and it's read write method are well documented. A simple Google search will reveal what these read write functions mean. E.g....

```auto
Function Code	Register Type
1	Read Coil
2	Read Discrete Input
3	Read Holding Registers
4	Read Input Registers
5	Write Single Coil
6	Write Single Holding Register
15	Write Multiple Coils
16	Write Multiple Holding Registers

```

Taken from...  
[https://www.csimn.com/CSI\_pages/Modbus101.html](https://www.csimn.com/CSI_pages/Modbus101.html)