# Modbus RS485 to USB communication

**URL:** <https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074>\
**Category:** Industrial\
**Created:** [22 May 2020 08:33 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074 "2020-05-22T08:33:16Z")\
**Posts on this page:** 12\
**Page:** 3

<div class="post-metadata">

**Author:** ![Robsky](https://avatars.discourse-cdn.com/v4/letter/r/c0e974/32.png) [@Robsky](https://discourse.nodered.org/u/Robsky)\
**Post date:** [27 May 2020 11:50 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/42 "2020-05-27T11:50:55Z")

</div>

maybe NODE-red has no access to your usb/com port where i believe your device is connected to, You mentioned usb-rs485 adapter connected direct to meter right, you proved that your connection is right with modscan, was such setup ever worked for you with diff device before? be sure that nothing ele is using this com port while you deploy node-red flow

---

<div class="post-metadata">

**Author:** ![Hasitha\_Sudasinghe](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hasitha_sudasinghe/32/22710_2.png) [@Hasitha\_Sudasinghe](https://discourse.nodered.org/u/Hasitha_Sudasinghe)\
**Post date:** [27 May 2020 11:55 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/43 "2020-05-27T11:55:13Z")

</div>

> [@Robsky](#):
>
> up ever worked for you with diff device before? be sure that nothing ele is using this com port while you deploy node-re

Yes you are correct. I think i have issues with my node red. i will try uninstall install node red again

---

<div class="post-metadata">

**Author:** ![edysuw](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/edysuw/32/22828_2.png) [@edysuw](https://discourse.nodered.org/u/edysuw)\
**Post date:** [28 May 2020 01:20 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/44 "2020-05-28T01:20:54Z")

</div>

hi...

how about the progress? still not working? maybe i can share my modbus rtu node for your reference

---

<div class="post-metadata">

**Author:** ![Hasitha\_Sudasinghe](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hasitha_sudasinghe/32/22710_2.png) [@Hasitha\_Sudasinghe](https://discourse.nodered.org/u/Hasitha_Sudasinghe)\
**Post date:** [29 May 2020 02:36 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/45 "2020-05-29T02:36:40Z")

</div>

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/8/6/8657b72d99e33b643070884f216959f8b0e7d679.png)

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/a/8/a8e3af5101d4ef4f633bd36938493be35d141376.png)

---

<div class="post-metadata">

**Author:** ![Hasitha\_Sudasinghe](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hasitha_sudasinghe/32/22710_2.png) [@Hasitha\_Sudasinghe](https://discourse.nodered.org/u/Hasitha_Sudasinghe)\
**Post date:** [29 May 2020 02:37 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/46 "2020-05-29T02:37:24Z")

</div>

Though i have uninstalled and installed i got no success 😰

---

<div class="post-metadata">

**Author:** ![edysuw](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/edysuw/32/22828_2.png) [@edysuw](https://discourse.nodered.org/u/edysuw)\
**Post date:** [29 May 2020 05:35 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/47 "2020-05-29T05:35:28Z")

</div>

hi, maybe u can compare with my node setup as seen below

node-red-modbus version:

 ![modbus-contrib-version](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/1/1/111ddcbcc422e96652f91a2d46262a489899fa7c.png)

modbus-getter setup:

 ![modbus-getter](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/0/e/0e8257baa4e7cf1da815c13876ff3b96e1127dca.png)

---

<div class="post-metadata">

**Author:** ![edysuw](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/edysuw/32/22828_2.png) [@edysuw](https://discourse.nodered.org/u/edysuw)\
**Post date:** [29 May 2020 05:36 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/48 "2020-05-29T05:36:05Z")

</div>

modbus-server setup:

 ![modbus-setup](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/0/9/09446b993770ff87164a9830c3f77f38b6fdd140.png)

nodered version:

 ![nodered version](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/8/f/8f6a5e07ad1a19b16c966c1c9a610305f95575a1.png)

---

<div class="post-metadata">

**Author:** ![edysuw](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/edysuw/32/22828_2.png) [@edysuw](https://discourse.nodered.org/u/edysuw)\
**Post date:** [29 May 2020 05:37 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/49 "2020-05-29T05:37:47Z")

</div>

nodejs version:  
 ![node-version](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/d/c/dcd86507a73fd5ac32ccf0f6ee3ef2863bd7834d.png)

and with this flow json

```auto
[{"id":"582f1736.87a998","type":"modbus-getter","z":"77e78410.d9584c","name":"","showStatusActivities":true,"showErrors":true,"logIOActivities":false,"unitid":"40","dataType":"HoldingRegister","adr":"15019","quantity":"2","server":"d44638ff.6e6458","useIOFile":false,"ioFile":"","useIOForPayload":false,"x":900,"y":660,"wires":[["f1eb0b8f.50bd58"],["cfc300f2.8b8aa"]]},{"id":"e8c6b3cc.59875","type":"inject","z":"77e78410.d9584c","name":"30s","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":"1","x":730,"y":660,"wires":[["582f1736.87a998"]]},{"id":"f1eb0b8f.50bd58","type":"debug","z":"77e78410.d9584c","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":1090,"y":640,"wires":[]},{"id":"cfc300f2.8b8aa","type":"debug","z":"77e78410.d9584c","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":1090,"y":680,"wires":[]},{"id":"d44638ff.6e6458","type":"modbus-client","z":"","name":"USB1","clienttype":"serial","bufferCommands":true,"stateLogEnabled":false,"tcpHost":"127.0.0.1","tcpPort":"502","tcpType":"DEFAULT","serialPort":"/dev/ttyUSB1","serialType":"RTU-BUFFERD","serialBaudrate":"19200","serialDatabits":"8","serialStopbits":"1","serialParity":"even","serialConnectionDelay":"5","unit_id":"","commandDelay":200,"clientTimeout":300,"reconnectTimeout":5}]

```

---

<div class="post-metadata">

**Author:** ![Hasitha\_Sudasinghe](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hasitha_sudasinghe/32/22710_2.png) [@Hasitha\_Sudasinghe](https://discourse.nodered.org/u/Hasitha_Sudasinghe)\
**Post date:** [29 May 2020 06:58 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/50 "2020-05-29T06:58:19Z")

</div>

Dear Friend,

In your case you are using USB port to take external device to node red. But in my case it shows as COM13 . I have uploaded all related data above in the chat for your reference.

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/3/9/398037c2398a39460c72e466f287a92c3613658e.png)

---

<div class="post-metadata">

**Author:** ![Hasitha\_Sudasinghe](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hasitha_sudasinghe/32/22710_2.png) [@Hasitha\_Sudasinghe](https://discourse.nodered.org/u/Hasitha_Sudasinghe)\
**Post date:** [29 May 2020 07:05 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/51 "2020-05-29T07:05:19Z")

</div>

this is what i got with your program. Its sure there is some thing that doesnt allow me to open the com port and do this job. Can i take any advice from any node red support guy. Do you have any contact of such a guy?

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/3/0/30a9abe44cc5c06b6c05b24cf9aff39a44a3ffc5.png)

---

<div class="post-metadata">

**Author:** ![Robsky](https://avatars.discourse-cdn.com/v4/letter/r/c0e974/32.png) [@Robsky](https://discourse.nodered.org/u/Robsky)\
**Post date:** [29 May 2020 07:32 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/52 "2020-05-29T07:32:13Z")

</div>

can you try to read full block of registers not just 1 or 2 from i.e. power table but all ?

---

<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:** [28 July 2020 07:32 UTC](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074/53 "2020-07-28T07:32:15Z")

</div>

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.

[Previous page](https://discourse.nodered.org/t/modbus-rs485-to-usb-communication/27074.md?page=2)