REXYGEN Community Forum

sudhir

Member

Registered: 2016-04-01

Posts: 14

Multiple MODBUS RTU Slave

We figured out how to add another slave but the read registers of that slave are not appearing in the dropdown for creating a new tag.
Is there a tutorial on how to add multiple MODBUS slaves? Thanks.

tomáš čechura

Administrator

Registered: 2016-02-22

Posts: 371

Re: Multiple MODBUS RTU Slave

Hey sudhir!

Thank you for your question. Another slave can be added by adding a new "Item" where you specify the "Slave address". Read registers won't appear in the dropdown menu until you add the items manually.
There isn't a way how to determine read/write registers of different Modbus devices automatically. You need to look for Register Table in documentation of each Modbus slave.

Hope it will help you find the right way.

Regards, Tomas

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Raspberry Pi as a miniature industrial PC. Analog and digital I/O, RS-485 and 1-Wire bus.

sudhir

Member

Registered: 2016-04-01

Posts: 14

Re: Multiple MODBUS RTU Slave

Thanks. We added in the "Special Edit"  dialog "Slave2 Slave addr 2 ReadReg 16 at address 0" to the items list. We want to associate that read reg to a from tag. We can't find a way to do that.

sudhir

Member

Registered: 2016-04-01

Posts: 14

Re: Multiple MODBUS RTU Slave

It appears to be a bug in the UI. We may to edit the mdl by hand.

tomáš čechura

Administrator

Registered: 2016-02-22

Posts: 371

Re: Multiple MODBUS RTU Slave

Hello sudhir,
the association of registers to a "From" tag isn't done automatically. You need to specify "GotoTag" parameter in "From" tag in order to link the register with the tag (e.g. MBM__temperature - for more details see documentation). It is also possible to use "INQUAD, INOCT, INHEXD" and change their name to link with the registers (e.g. MBM__localIPaddress).

Hope that this is now a bit more clearer.

Regards, Tomas

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Raspberry Pi as a miniature industrial PC. Analog and digital I/O, RS-485 and 1-Wire bus.

sudhir

Member

Registered: 2016-04-01

Posts: 14

Re: Multiple MODBUS RTU Slave

The issue is that the new items don't appear in the dropdown to make the connections. You have to edit it by hand.

tomáš čechura

Administrator

Registered: 2016-02-22

Posts: 371

Re: Multiple MODBUS RTU Slave

Do you mean the dropdown menu of "From" tag?

For now, it is a feature not a bug.
We see your point and share your idea. Unfortunately, it can't be implemented automatically because of multi I/O flags I mentioned in previous post.

Hope that this is not a big issue for you.
Have a nice day,
Tomas

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Raspberry Pi as a miniature industrial PC. Analog and digital I/O, RS-485 and 1-Wire bus.