# Modbus RS485 read errors?

**URL:** <https://discourse.nodered.org/t/modbus-rs485-read-errors/86070>\
**Category:** General\
**Created:** [2 March 2024 06:37 UTC](https://discourse.nodered.org/t/modbus-rs485-read-errors/86070 "2024-03-02T06:37:06Z")\
**Posts on this page:** 10\
**Page:** 1

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**Author:** ![4711Austria](https://avatars.discourse-cdn.com/v4/letter/4/c6cbf5/32.png) [@4711Austria](https://discourse.nodered.org/u/4711Austria)\
**Post date:** [2 March 2024 06:37 UTC](https://discourse.nodered.org/t/modbus-rs485-read-errors/86070/1 "2024-03-02T06:37:06Z")

</div>

Hello  
would need some hlp pls, to understand, where is my fault, thx!

reading via RS485/USB Adapter from a BMS Batterypack.  
connected are 1/8 2/7 (no ground - does have a problem on pack off getting voltage)  
pallette @kenke7/node-red-contrib-modbus

```auto
[{"id":"2abf9c4452d8f5b8","type":"tab","label":"Flow 1","disabled":false,"info":"","env":[]},{"id":"04b022aeb3ed5f8e","type":"mqtt-broker","name":"Cerbo ESS","broker":"192.168.0.191","port":"1883","clientid":"","autoConnect":true,"usetls":false,"protocolVersion":"4","keepalive":"60","cleansession":true,"birthTopic":"","birthQos":"0","birthPayload":"","birthMsg":{},"closeTopic":"","closeQos":"0","closePayload":"","closeMsg":{},"willTopic":"","willQos":"0","willPayload":"","willMsg":{},"userProps":"","sessionExpiry":""},{"id":"1ae4efd6331d23c0","type":"modbus-client","name":"Gobel","clienttype":"serial","bufferCommands":true,"stateLogEnabled":false,"queueLogEnabled":false,"failureLogEnabled":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":"200","serialAsciiResponseStartDelimiter":"0x3A","unit_id":"1","commandDelay":"1","clientTimeout":"200","reconnectOnTimeout":true,"reconnectTimeout":"2000","parallelUnitIdsAllowed":true,"showWarnings":true,"showLogs":true},{"id":"cbe2856bef552594","type":"modbus-read","z":"2abf9c4452d8f5b8","name":"Read Gobel","topic":"","showStatusActivities":false,"logIOActivities":false,"showErrors":true,"showWarnings":true,"unitid":"1","dataType":"HoldingRegister","adr":"0","quantity":"4","rate":"10","rateUnit":"s","delayOnStart":false,"startDelayTime":"1","server":"1ae4efd6331d23c0","useIOFile":false,"ioFile":"","useIOForPayload":false,"emptyMsgOnFail":true,"x":150,"y":140,"wires":[["3fe430a9b3308300","728dd3ce014257b7"],["3191110821f85424"]]},{"id":"3fe430a9b3308300","type":"debug","z":"2abf9c4452d8f5b8","name":"debug 2","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"payload","targetType":"msg","statusVal":"payload","statusType":"auto","x":360,"y":140,"wires":[]},{"id":"3191110821f85424","type":"debug","z":"2abf9c4452d8f5b8","name":"debug 3","active":false,"tosidebar":true,"console":false,"tostatus":true,"complete":"payload","targetType":"msg","statusVal":"payload","statusType":"auto","x":360,"y":200,"wires":[]},{"id":"728dd3ce014257b7","type":"change","z":"2abf9c4452d8f5b8","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"payload[0]","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":310,"y":300,"wires":[["fb9846fe99e46e1f"]]},{"id":"fb9846fe99e46e1f","type":"debug","z":"2abf9c4452d8f5b8","name":"debug 4","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"payload","targetType":"msg","statusVal":"payload","statusType":"auto","x":520,"y":300,"wires":[]}]

```

 ![IMG_8032](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/e/3/e31a013502cd31c223432817bec6144d53a85f22.jpeg)

first I get the value, then nothing anymore?

 ![Bildschirmfoto 2024-03-02 um 07.32.40](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/9/e/9e8c9e46b21e73513d28c8b542284cefab7adb3b.png)

THX

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<div class="post-metadata">

**Author:** ![4711Austria](https://avatars.discourse-cdn.com/v4/letter/4/c6cbf5/32.png) [@4711Austria](https://discourse.nodered.org/u/4711Austria)\
**Post date:** [2 March 2024 06:46 UTC](https://discourse.nodered.org/t/modbus-rs485-read-errors/86070/2 "2024-03-02T06:46:13Z")

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![Bildschirmfoto 2024-03-02 um 07.43.44](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/b/8/b81d4d7a635b2bfaafc3be5bad97ad3591058d2e.png)  
 ![Bildschirmfoto 2024-03-02 um 07.44.17](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/7/f/7f117939c8bc885735f1f29d4e187f12a0f222af.png)

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<div class="post-metadata">

**Author:** ![4711Austria](https://avatars.discourse-cdn.com/v4/letter/4/c6cbf5/32.png) [@4711Austria](https://discourse.nodered.org/u/4711Austria)\
**Post date:** [2 March 2024 06:49 UTC](https://discourse.nodered.org/t/modbus-rs485-read-errors/86070/3 "2024-03-02T06:49:46Z")

</div>

![Bildschirmfoto 2024-03-02 um 07.44.27](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/d/4/d4e182188a3034a8dab2c197002af8691889016c.png)

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<div class="post-metadata">

**Author:** ![4711Austria](https://avatars.discourse-cdn.com/v4/letter/4/c6cbf5/32.png) [@4711Austria](https://discourse.nodered.org/u/4711Austria)\
**Post date:** [2 March 2024 07:08 UTC](https://discourse.nodered.org/t/modbus-rs485-read-errors/86070/4 "2024-03-02T07:08:39Z")

</div>

changed wiring, only 1 B and 2 A is connected, no change

sometimes I get values, most not, where is the problem ?

 ![Bildschirmfoto 2024-03-02 um 08.07.44](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/1/9/199ec93705ef6c542636e528986a583656dca719.png)

I always get an error message with expected x and got "9", is that something of interest?

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<div class="post-metadata">

**Author:** ![4711Austria](https://avatars.discourse-cdn.com/v4/letter/4/c6cbf5/32.png) [@4711Austria](https://discourse.nodered.org/u/4711Austria)\
**Post date:** [2 March 2024 07:13 UTC](https://discourse.nodered.org/t/modbus-rs485-read-errors/86070/5 "2024-03-02T07:13:30Z")

</div>

this is the doc I am following from manufacturer

> <https://github.com/syssi/esphome-pace-bms/blob/main/docs/PACE-BMS-Modbus-Protocol-for-RS485-V1.3-20170627.pdf>

> **[GitHub - fancyui/Gobel-Power-RN-BMS-RS485-ModBus: Gobel Power LiFePO4 Battery...](https://github.com/fancyui/Gobel-Power-RN-BMS-RS485-ModBus)**
>
> Gobel Power LiFePO4 Battery RN BMS RS485 Modbus Communication - fancyui/Gobel-Power-RN-BMS-RS485-ModBus

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<div class="post-metadata">

**Author:** ![4711Austria](https://avatars.discourse-cdn.com/v4/letter/4/c6cbf5/32.png) [@4711Austria](https://discourse.nodered.org/u/4711Austria)\
**Post date:** [2 March 2024 07:17 UTC](https://discourse.nodered.org/t/modbus-rs485-read-errors/86070/6 "2024-03-02T07:17:59Z")

</div>

> **[fancyui - Overview](https://github.com/fancyui)**
>
> Gobel Power Official. fancyui has 3 repositories available. Follow their code on GitHub.

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<div class="post-metadata">

**Author:** ![4711Austria](https://avatars.discourse-cdn.com/v4/letter/4/c6cbf5/32.png) [@4711Austria](https://discourse.nodered.org/u/4711Austria)\
**Post date:** [2 March 2024 07:20 UTC](https://discourse.nodered.org/t/modbus-rs485-read-errors/86070/7 "2024-03-02T07:20:22Z")

</div>

it seams there is something fixed to "9" ?  
tried address:0 quantity: 1

 ![Bildschirmfoto 2024-03-02 um 08.19.21](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/c/f/cf362d574bd2f8f0e087ff1a7794692af9c586dd.png)

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<div class="post-metadata">

**Author:** ![4711Austria](https://avatars.discourse-cdn.com/v4/letter/4/c6cbf5/32.png) [@4711Austria](https://discourse.nodered.org/u/4711Austria)\
**Post date:** [2 March 2024 07:28 UTC](https://discourse.nodered.org/t/modbus-rs485-read-errors/86070/8 "2024-03-02T07:28:37Z")

</div>

address: 0 quantity: 2

 ![Bildschirmfoto 2024-03-02 um 08.28.18](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/9/3/93d67e2389e93cc377f301bb0e2a857c18a0d608.png)  
851 = 8,51A  
5364 = 53,64V  
these values are correct

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<div class="post-metadata">

**Author:** ![4711Austria](https://avatars.discourse-cdn.com/v4/letter/4/c6cbf5/32.png) [@4711Austria](https://discourse.nodered.org/u/4711Austria)\
**Post date:** [2 March 2024 07:33 UTC](https://discourse.nodered.org/t/modbus-rs485-read-errors/86070/9 "2024-03-02T07:33:27Z")

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maybe this is the hint:

 ![Bildschirmfoto 2024-03-02 um 08.33.06](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/8/8/88fd905f149af69cdfac9c95eac8463bad8b7ad5.png)

this is just the 8 data bits and 1 stop bit or?

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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:** [31 May 2024 07:33 UTC](https://discourse.nodered.org/t/modbus-rs485-read-errors/86070/10 "2024-05-31T07:33:43Z")

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