what is the minimum number of Modbus RTU master as virtual device we can configure in pictory ?

[Anil]

Hello, kunbus team,

We have a certain number of slaves and we have around 1000 tags for those slaves. In order to map those slaves to Modbus RTU master 150 in pictory, we need around 7 virtual devices (Modbus RTU master 150 ). As per your document for Modbus RTU master, we can use more than one Modbus RTU master. Exactly How many Modbus RTU master 150 we can use as virtual device?
Does it is possible to map one slave to more than one Modbus RTU master 150?
Does it is possible to map more than one slave to a single Modbus RTU master 150?

[Ashish]

Hi Dirk & Team,
We are trying to implement a Data logging application for Solar Industry in India. Wherein our Rev Pi will act as a data logging H/w with additional software from our software partners.
So based on the above inputs from my colleague Mr. Anil, we have some 1K approx tags of RS-485 in Inverter block which are to be stored in our Revolution Pi and transferred to cloud via MQTT or HTTP.
Please clarify if our device will suffice to these requirements.

[dirk]

Hi Ashish, per interface you can just use one ModbusRTU Master as there are rest periods on the bus. You can use more USB 2.0 to 2 x serial RS-485 adapters to handle this. Have in mind that with the Modbus 150 Virtual Module you have to expect poor PiCtory performance. There is a check which performs unique variable names.

[Anil]

Hi, dirk Thanks for your response,
"per interface you can just use one ModbusRTU Master as there are rest periods on the bus"

I did not understand what you are trying to say in the above line especially the rest periods on the bus
Will you please elaborate or give more explanation about it.

[dirk]

Hi Anil, have a look at this post and this Blog entry. I and other people cannot recommend it and we do not support it. But our system is open so that you might be able to implement a multi master solution yourself.

[Anil]

Site:250 Mw
Inverter Size: 12.5MW, so a total of 20 in number.
Tag Size: Per inverter 400 tags.
Data polling frequency: 1minute.
Datalogger should collect from the each inverter and send to local server wireless.

Now here we want to use RevPi core / connect as datalogger. if we use RevPi connect as Modbus RTU 150 master as a virtual device we have to add three devices in Pictory, so 400 tags per slave can be interface with one RevPi connect. Does this more than one master(virtual) to one slave lead Collison?

Please Replay as early as possible.

[dirk]

Hi Anil, as mentioned before the Modbus-RTU physical layer is no shared medium. Thus just one master may access one physical line. But you may use USB-RS485 devices to extend your need for multiple masters. In case the information you need is placed in consecutive registers you may work access multiple registes by one action. See the Tutorial How to Use RevPi Connect as Modbus RTU Master.

[Anil]

Thanks a lot for your response dirk.

[dirk]

You're welcome