# Modbus RTU Serial Reading Coils failed

**URL:** https://discourse.nodered.org/t/modbus-rtu-serial-reading-coils-failed/25071
**Category:** General
**Created:** [18 April 2020 12:50 UTC](https://discourse.nodered.org/t/modbus-rtu-serial-reading-coils-failed/25071 "2020-04-18T12:50:13Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![jsail](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/jsail/32/20176_2.png) [@jsail](https://discourse.nodered.org/u/jsail)
#### Post date: [18 April 2020 12:50 UTC](https://discourse.nodered.org/t/modbus-rtu-serial-reading-coils-failed/25071/1 "2020-04-18T12:50:13Z")

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I can not get the values of the coils in address (0:65535). The device is a powermeter. I need the value in address 240. The FC1 'Read Coil Status' does not give me any value back.

Using my Modbus CMD Tool, I have to use FC3 'Read Holding Registers'. But because its not ModBusConform, it does not work this way in node-red and shows this error:

Error: Modbus exception 1: Illegal function (device does not support this read/write function)

Thanks for help.  
Joseph

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<div class="post-metadata">

### Author: ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)
#### Post date: [17 June 2020 12:50 UTC](https://discourse.nodered.org/t/modbus-rtu-serial-reading-coils-failed/25071/2 "2020-06-17T12:50:24Z")

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