# Modbus communication between two robots ur5

**URL:** <https://forum.universal-robots.com/t/modbus-communication-between-two-robots-ur5/25264>\
**Category:** Robot Communication\
**Created:** [November 24, 2022, 4:57pm UTC](https://forum.universal-robots.com/t/modbus-communication-between-two-robots-ur5/25264 "2022-11-24T16:57:58Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![a.tena](https://avatars.discourse-cdn.com/v4/letter/a/13edae/32.png) [@a.tena](https://forum.universal-robots.com/u/a.tena)\
**Post date:** [November 24, 2022, 4:57pm UTC](https://forum.universal-robots.com/t/modbus-communication-between-two-robots-ur5/25264/1 "2022-11-24T16:57:58Z")

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Hi.

I have two ur5 robots connected to a siemens switch. I have configured the Modbus communication between them, in one of them it appears connected, but in the other one the status of the unit is always connecting.

I have done the test with two virtual machines and it works perfectly.

In the robots, I have the static ip, without default gateway.

How could I debug the communication of the robot that does not finish connecting?

Any ideas?

Thanks in advance.  
Alejandro.

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**Author:** ![terryc](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/terryc/32/3006_2.png) [@terryc](https://forum.universal-robots.com/u/terryc)\
**Post date:** [November 25, 2022, 5:09pm UTC](https://forum.universal-robots.com/t/modbus-communication-between-two-robots-ur5/25264/2 "2022-11-25T17:09:57Z")

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I’m not sure if the robots are Modbus TCP servers. They are definitely clients that connect to Modbus server devices. Did you find a list of registers to connect to between robots?

Edit: I take it back, I guess I’ve never had to use it that way  
[https://www.universal-robots.com/articles/ur/interface-communication/modbus-server/](https://www.universal-robots.com/articles/ur/interface-communication/modbus-server/)

> **[ModBus%20server%20data.pdf](https://s3-eu-west-1.amazonaws.com/ur-support-site/16377/ModBus%20server%20data.pdf)**
>
> 451.46 KB

One way you could debug is try connecting using client software on the PC. I use this one for a lot of testing:

> **[TCP Modbus Examiner tool with a modern UI - Mina Andrawos](https://www.minaandrawos.com/tcp-modbus-examiner-tool/)**
>
> A Modbus examiner tool to test TCP Modbus devices. This tool was built from the ground up with a modern friendly user interface, and useful features.

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<div class="post-metadata">

**Author:** ![a.tena](https://avatars.discourse-cdn.com/v4/letter/a/13edae/32.png) [@a.tena](https://forum.universal-robots.com/u/a.tena)\
**Post date:** [November 29, 2022, 11:09am UTC](https://forum.universal-robots.com/t/modbus-communication-between-two-robots-ur5/25264/3 "2022-11-29T11:09:28Z")

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Thanks Terryc, I’ll see if I can try it, as I’m not in the lab right now where the two UR3 are. I’ll try the TCP Modbus Examiner client and I’ll share the results with you.

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**Author:** ![sven.gleich](https://avatars.discourse-cdn.com/v4/letter/s/ba9def/32.png) [@sven.gleich](https://forum.universal-robots.com/u/sven.gleich)\
**Post date:** [December 1, 2022, 6:24am UTC](https://forum.universal-robots.com/t/modbus-communication-between-two-robots-ur5/25264/4 "2022-12-01T06:24:56Z")

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Dear Alejandro,

we have an application where 3 cobots (UR10, not eSeries) are working together sharing sometimes the same workspace. They were connected by a Siemens switch. You may have a look at the pdf how the concept looked like and how the modbus I/O settings where configured. Screenshots are in German but I made some annotation for the English expressions.

If you need the network config of the URs too give me a short reply.  
[3cob\_together.pdf](https://forum.universal-robots.com/uploads/short-url/kirxe5G2RaF4GHVGQk7KHRRTItp.pdf) (186.0 KB)

Regards, Sven