# Modbus RTU issues
**URL:** https://discourse.nodered.org/t/modbus-rtu-issues/34445
**Category:** General
**Created:** [18 October 2020 10:53 UTC](https://discourse.nodered.org/t/modbus-rtu-issues/34445 "2020-10-18T10:53:57Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@craigcurtin](https://discourse.nodered.org/u/craigcurtin)
#### Post date: [18 October 2020 10:53 UTC](https://discourse.nodered.org/t/modbus-rtu-issues/34445/1 "2020-10-18T10:53:57Z")
Guys,
I have a 3 phase energy meter - ACREL DTSD1352 /ADL3000 - it is configured as 9600,N,8,1 on Address 1.
I have a Linux (Ubuntu 18.04) on a laptop.
I have a USB/RS485 dongle - this is installed and presenting itself as /dev/ttyUSB0
From the commandline i can use a program mbmd - [https://github.com/volkszaehler/mbmd](https://github.com/volkszaehler/mbmd) that is designed to query energy monitors etc and works well.
My monitor is not natively supported - however using a development feature i have been able to succesfully query the meter and return information - some DWORD, other WORD registers etc - all seems fine.
I am now on the same machine trying to use NR to query this unit - i have tried a number of modbus modules - i currently have both of these installed
And have done the following test flow
```auto
[{"id":"942f710f.4b0c1","type":"debug","z":"76274d8e.fd5214","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":610,"y":120,"wires":[]},{"id":"d81a7895.7e6cc8","type":"modbus-read","z":"76274d8e.fd5214","name":"test","topic":"","showStatusActivities":false,"logIOActivities":false,"showErrors":false,"unitid":"1","dataType":"InputRegister","adr":"0","quantity":"2","rate":"10","rateUnit":"s","delayOnStart":false,"startDelayTime":"","server":"425ee67b.5cd4c8","useIOFile":false,"ioFile":"","useIOForPayload":false,"emptyMsgOnFail":false,"x":310,"y":120,"wires":[["942f710f.4b0c1"],["953ca3d7.4b557"]]},{"id":"953ca3d7.4b557","type":"debug","z":"76274d8e.fd5214","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":610,"y":180,"wires":[]},{"id":"425ee67b.5cd4c8","type":"modbus-client","z":"","name":"ADL3000","clienttype":"simpleser","bufferCommands":true,"stateLogEnabled":true,"queueLogEnabled":true,"tcpHost":"127.0.0.1","tcpPort":"502","tcpType":"DEFAULT","serialPort":"/dev/ttyUSB0","serialType":"RTU-BUFFERD","serialBaudrate":"9600","serialDatabits":"8","serialStopbits":"1","serialParity":"none","serialConnectionDelay":"100","unit_id":"1","commandDelay":"1000","clientTimeout":"1000","reconnectOnTimeout":true,"reconnectTimeout":"5000","parallelUnitIdsAllowed":false}]
```
But am getting absolutely nothing back in the debug window - i have tried a number of different registers and all of the options that the nodes supply
I have tried NR running as a normal user and also as root - and this has made not difference
Any ideas how i can troubleshoot this one ?
Craig
---
### Author:  [@craigcurtin](https://discourse.nodered.org/u/craigcurtin)
#### Post date: [19 October 2020 09:24 UTC](https://discourse.nodered.org/t/modbus-rtu-issues/34445/2 "2020-10-19T09:24:03Z")
A couple of things here
Change the logging option in NR to debug so you can get better info.
Turns out to be a Linux permissions issue on the USB/Serial driver - apparently the only group with access is the Dialout group - so whichever user you use to run NR, should be given permissions/membership to that group.
Craig
---
### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [18 December 2020 09:24 UTC](https://discourse.nodered.org/t/modbus-rtu-issues/34445/3 "2020-12-18T09:24:31Z")
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