Question

via cellular network. Can we send this data to server as a client (in other words: if something comes from RS485 - convert it to Modbus TCP and send to specified ip address/port)? And if it is possible - what shall we configure on RTU955 (I find nothing about this in manual).

Answer 1

Hello,

Yes, this is possible. Simply navigate to "Services -> RS232/RS485 -> RS485" menu and configure the service:

• Use "Serial type: Over IP" and "Mode: Client"
• You can leave "Reconnect interval (s)" value empty or enter e.g. "5" seconds for more aggressive connection

Comments

I'm a bit confused...
I am already doing some custom modbus onboard the RUT955 and then pushing that to the thingsboard portal

I also want to poll data from a modbus RTU device via rs485
I have already verified 485 comms to the device.
Seems to me in Services -> RS485 the RUT must be configured as a Master

The master address will also be 192.168.1.1
The slave device is currently ID 1 does that need to be changed so it doesn't conflict with the onboard ID 1
Actually, I would likely change the onboard ID to 11 or something so I can just leave the devices with their default ID 1.
I'm still a bit confused about the role of ID on TCP vs RTU side

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Hello kurtklingbeil,

In your particular situation, you might need to use a different router's functionalities:

 - In the "Services -> Modbus -> Modbus TCP Master" menu you can configure the router to be a Modbus Master. From this menu, you could also specify your Modbus Slave device's ID (yes, it can be left as ID 1). In case you would also like a router to act as Modbus TCP Slave simultaneously, that can be configured from the "Services -> Modbus -> Modbus TCP Slave" menu. Here you can also configure the router's Modbus Slave ID.

 - Similarly, in the "Services -> Modbus -> Modbus Serial Master" menu you can configure the router to be a Modbus Serial Master (i.e. over RS485 line)

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You Write:
In your particular situation, you might need to use a different router's functionalities:
What does that mean exactly ?  The 955 cannot gateway RTU to TCP and then to cloud ?

I've got the internal 955 registers reading and pushing OK plus the Custom modbus reading from /tmp/regfile OK
(although the custom mysteriously stopped working, and just as mysteriously resumed working while I was monkeying around attempting to get the RTU device reading...

What I have discovered is that the 955 internal modbus registers cannot be accessed from the modbus master unless the modbus slave has been correctly configured.  I get the sense that the 485 connection is also dependent on or interferes with the modbus slave

WTH is the 485 configuration for if it doesn't actually gateway the data ?
I have tried configuring the 485 as a client and a server and bidirectional and as modbus Gateway.
It seemed to break the existing modbus traffic...  I attempted to just use a non-standard port 503

If I were to scrap the connections to the 955 modbus and custom modbus and only read from the RTU and push that up to the cloud is that possible ?

Answer 2

Hi,

Router has Modbus gateway Serial type which allows redirecting TCP data coming to a specified port to RTU specified by the Slave ID. The Slave ID can be specified by the user or be obtained directly from the Modbus header.

Basically request to your device (connected to router RS485) should arrive from server.

Comments

Does this also translate the Modbus-RTU data to Modbus-TCP? As I know Modbus-TCP has no checksum in data. So if it's only a transparent connection it will not work with an Modbus-TCP client.

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For more details please check here: https://wiki.teltonika.lt/view/RUT955_Modbus